Temperature regime of the underlying surface. Thermal regime of the earth's surface and atmosphere

Thermal energy enters the lower layers of the atmosphere mainly from the underlying surface. The thermal regime of these layers

is closely related to the thermal regime of the earth's surface, so its study is also one of the important tasks of meteorology.

The main physical processes in which the soil receives or gives off heat are: 1) radiant heat transfer; 2) turbulent heat exchange between the underlying surface and the atmosphere; 3) molecular heat exchange between the soil surface and the lower fixed adjacent air layer; 4) heat exchange between soil layers; 5) phase heat transfer: heat consumption for water evaporation, melting of ice and snow on the surface and in the depth of the soil, or its release during reverse processes.

The thermal regime of the surface of the earth and water bodies is determined by their thermophysical characteristics. Special attention in preparation, one should pay attention to the derivation and analysis of the soil thermal conductivity equation (Fourier equation). If the soil is uniform vertically, then its temperature t at a depth z at time t can be determined from the Fourier equation

where a- thermal diffusivity of the soil.

The consequence of this equation are the basic laws of the propagation of temperature fluctuations in the soil:

1. The law of invariance of the oscillation period with depth:

T(z) = const(2)

2. The law of decrease in the amplitude of oscillations with depth:

(3)

where and are amplitudes at depths a- thermal diffusivity of the soil layer lying between the depths ;

3. The law of the phase shift of oscillations with depth (the law of delay):

(4)

where is the delay, i.e. the difference between the moments of the onset of the same phase of oscillations (for example, maximum) at depths and Temperature fluctuations penetrate the soil to a depth znp defined by the ratio:

(5)

In addition, it is necessary to pay attention to a number of consequences from the law of decrease in the amplitude of oscillations with depth:

a) the depths at which in different soils ( ) amplitudes of temperature fluctuations with the same period ( = T 2) decrease by the same number of times relate to each other as square roots of the thermal diffusivity of these soils

b) the depths at which in the same soil ( a= const) amplitudes of temperature fluctuations with different periods ( ) decrease by the same amount =const, are related to each other as the square roots of the periods of oscillations

(7)

It is necessary to clearly understand the physical meaning and features of the formation of heat flow into the soil.

The surface density of the heat flux in the soil is determined by the formula:

where λ is the coefficient of thermal conductivity of the soil vertical temperature gradient.

Instant value R are expressed in kW/m to the nearest hundredth, the sums R - in MJ / m 2 (hourly and daily - up to hundredths, monthly - up to units, annual - up to tens).

The average surface heat flux density through the soil surface over a time interval t is described by the formula

where C is the volumetric heat capacity of the soil; interval; z „ p- depth of penetration of temperature fluctuations; ∆tcp- the difference between the average temperatures of the soil layer to the depth znp at the end and at the beginning of the interval m. Let us give the main examples of tasks on the topic “Thermal regime of the soil”.

Task 1. At what depth does it decrease in e times the amplitude of diurnal fluctuations in soil with a coefficient of thermal diffusivity a\u003d 18.84 cm 2 / h?

Decision. It follows from equation (3) that the amplitude of diurnal fluctuations will decrease by a factor of e at a depth corresponding to the condition

Task 2. Find the depth of penetration of daily temperature fluctuations into granite and dry sand, if the extreme surface temperatures of adjacent areas with granite soil are 34.8 °C and 14.5 °C, and with dry sandy soil 42.3 °C and 7.8 °C . thermal diffusivity of granite a g \u003d 72.0 cm 2 / h, dry sand a n \u003d 23.0 cm 2 / h.

Decision. The temperature amplitude on the surface of granite and sand is equal to:

The penetration depth is considered by the formula (5):

Due to the greater thermal diffusivity of granite, we also obtained a greater penetration depth of daily temperature fluctuations.

Task 3. Assuming that the temperature of the upper soil layer changes linearly with depth, one should calculate the surface heat flux density in dry sand if its surface temperature is 23.6 "WITH, and the temperature at a depth of 5 cm is 19.4 °C.

Decision. The temperature gradient of the soil in this case is equal to:

Thermal conductivity of dry sand λ= 1.0 W/m*K. The heat flux into the soil is determined by the formula:

P = -λ - = 1.0 84.0 10 "3 \u003d 0.08 kW / m 2

The thermal regime of the surface layer of the atmosphere is determined mainly by turbulent mixing, the intensity of which depends on dynamic factors (roughness of the earth's surface and wind speed gradients at different levels, scale of movement) and thermal factors (inhomogeneity of heating of various parts of the surface and vertical temperature distribution).

To characterize the intensity of turbulent mixing, the turbulent exchange coefficient is used BUT and turbulence coefficient TO. They are related by the ratio

K \u003d A / p(10)

where R - air density.

Turbulence coefficient To measured in m 2 / s, accurate to hundredths. Usually, in the surface layer of the atmosphere, the turbulence coefficient is used TO] on high G"= 1 m. Within the surface layer:

where z- height (m).

You need to know the basic methods for determining TO\.

Task 1. Calculate the surface density of the vertical heat flux in the surface layer of the atmosphere through the area at which the air density is normal, the turbulence coefficient is 0.40 m 2 /s, and the vertical temperature gradient is 30.0 °C/100m.

Decision. We calculate the surface density of the vertical heat flux by the formula

L=1.3*1005*0.40*

Study the factors affecting the thermal regime of the surface layer of the atmosphere, as well as periodic and non-periodic changes in the temperature of the free atmosphere. The equations of heat balance of the earth's surface and atmosphere describe the law of conservation of energy received by the active layer of the Earth. Consider the daily and annual course of the heat balance and the reasons for its changes.

Literature

Chapter Sh, ch. 2, § 1 -8.

Questions for self-examination

1. What factors determine the thermal regime of soil and water bodies?

2. What is the physical meaning of thermophysical characteristics and how do they affect the temperature regime of soil, air, water?

3. What do the amplitudes of daily and annual fluctuations in soil surface temperature depend on and how do they depend on?

4. Formulate the basic laws of distribution of temperature fluctuations in the soil?

5. What are the consequences of the basic laws of the distribution of temperature fluctuations in the soil?

6. What are the average depths of penetration of daily and annual temperature fluctuations in the soil and in water bodies?

7. What is the effect of vegetation and snow cover on the thermal regime of the soil?

8. What are the features of the thermal regime of water bodies, in contrast to the thermal regime of the soil?

9. What factors influence the intensity of turbulence in the atmosphere?

10. What quantitative characteristics of turbulence do you know?

11. What are the main methods for determining the turbulence coefficient, their advantages and disadvantages?

12. Draw and analyze the daily course of the turbulence coefficient over land and water surfaces. What are the reasons for their difference?

13. How is the surface density of the vertical turbulent heat flux in the surface layer of the atmosphere determined?

Soil is a component of the climate system, which is the most active accumulator of solar heat entering the earth's surface.

The daily course of the underlying surface temperature has one maximum and one minimum. The minimum occurs around sunrise, the maximum occurs in the afternoon. The phase of the diurnal cycle and its daily amplitude depend on the season, the state of the underlying surface, the amount and precipitation, and also, on the location of the stations, the type of soil and its mechanical composition.

According to the mechanical composition, soils are divided into sandy, sandy loamy and loamy soils, which differ in heat capacity, thermal diffusivity and genetic properties (in particular, in color). Dark soils absorb more solar radiation and therefore warm up more than light soils. Sandy and sandy loamy soils, characterized by a smaller, warmer than loamy.

The annual course of the underlying surface temperature shows a simple periodicity with a minimum in winter and a maximum in summer. In most of the territory of Russia, the highest soil temperature is observed in July, on Far East in the coastal strip of the Sea of ​​Okhotsk, on and - in July - August, in the south of Primorsky Krai - in August.

The maximum temperatures of the underlying surface during most of the year characterize the extreme thermal state of the soil, and only for the coldest months - the surface.

The weather conditions favorable for the underlying surface to reach maximum temperatures are: slightly cloudy weather, when the influx of solar radiation is maximum; low wind speeds or calm, since an increase in wind speed increases the evaporation of moisture from the soil; a small amount of precipitation, since dry soil is characterized by lower heat and thermal diffusivity. In addition, in dry soil there is less heat consumption for evaporation. Thus, absolute temperature maxima are usually observed on the clearest sunny days on dry soil and usually in the afternoon hours.

The geographical distribution of averages from the absolute annual maxima of the underlying surface temperature is similar to the distribution of isogeotherms of the average monthly temperatures of the soil surface in summer months. Isogeotherms are mainly latitudinal. The influence of the seas on the temperature of the soil surface is manifested in the fact that on the western coast of Japan and, on Sakhalin and Kamchatka, the latitudinal direction of the isogeoterms is disturbed and becomes close to the meridional (repeats the outlines of the coastline). In the European part of Russia, the values ​​of the average of the absolute annual maxima of the underlying surface temperature vary from 30–35°C on the coast of the northern seas to 60–62°C in the south of the Rostov Region, in the Krasnodar and Stavropol Territories, in the Republic of Kalmykia and the Republic of Dagestan. In the area, the average of the absolute annual maxima of soil surface temperature is 3–5°C lower than in the nearby flat areas, which is associated with the influence of elevations on the increase in precipitation in the area and soil moisture. Plain territories, closed by hills from the prevailing winds, are characterized by a reduced amount of precipitation and lower wind speeds, and, consequently, increased values ​​of extreme temperatures of the soil surface.

The most rapid increase in extreme temperatures from north to south occurs in the zone of transition from the forest and zones to the zone, which is associated with a decrease in precipitation in the steppe zone and with a change in soil composition. In the south, with a general low level of moisture content in the soil, the same changes in soil moisture correspond to more significant differences in the temperature of soils that differ in mechanical composition.

There is also a sharp decrease in the average of the absolute annual maximums of the temperature of the underlying surface from south to north in the northern regions of the European part of Russia, during the transition from the forest zone to zones and tundra - areas of excessive moisture. The northern regions of the European part of Russia, due to active cyclonic activity, among other things, differ from the southern regions in an increased amount of cloudiness, which sharply reduces the arrival of solar radiation to the earth's surface.

In the Asian part of Russia, the lowest average absolute maxima occur on the islands and in the north (12–19°C). As we move southward, there is an increase in extreme temperatures, and in the north of the European and Asian parts of Russia, this increase occurs more sharply than in the rest of the territory. In areas with a minimum amount of precipitation (for example, the areas between the Lena and Aldan rivers), pockets of increased extreme temperatures are distinguished. Since the regions are very complex, the extreme temperatures of the soil surface for stations located in various forms of relief (mountainous regions, basins, lowlands, valleys of large Siberian rivers) differ greatly. The average values ​​of the absolute annual maxima of the underlying surface temperature reach the highest values ​​in the south of the Asian part of Russia (except for coastal areas). In the south of Primorsky Krai, the average of absolute annual maxima is lower than in continental regions located at the same latitude. Here their values ​​reach 55–59°C.

The minimum temperatures of the underlying surface are also observed under quite specific conditions: on the coldest nights, at hours close to sunrise, during anticyclonic weather conditions, when low cloudiness favors maximum effective radiation.

The distribution of average isogeotherms from the absolute annual minima of the underlying surface temperature is similar to the distribution of isotherms of minimum air temperatures. In most of the territory of Russia, except for the southern and northern regions, the average isogeotherms of the absolute annual minimum temperatures of the underlying surface take on a meridional orientation (decreasing from west to east). In the European part of Russia, the average of the absolute annual minimum temperatures of the underlying surface varies from -25°C in the western and southern regions to -40 ... -45°C in the eastern and, especially, northeastern regions (Timan Ridge and Bolshezemelskaya tundra). The highest mean values ​​of absolute annual temperature minima (–16…–17°C) occur on the Black Sea coast. In most of the Asian part of Russia, the average of the absolute annual minimums vary within -45 ... -55 ° С. Such an insignificant and fairly uniform distribution of temperature over a vast territory is associated with the uniformity of the conditions for the formation of minimum temperatures in areas subject to the influence of the Siberian.

In areas of Eastern Siberia with complex relief, especially in the Republic of Sakha (Yakutia), along with radiation factors, relief features have a significant effect on the decrease in minimum temperatures. Here, in the difficult conditions of a mountainous country in depressions and basins, especially favorable conditions are created for cooling the underlying surface. The Republic of Sakha (Yakutia) has the lowest mean values ​​of the absolute annual minimums of the underlying surface temperature in Russia (up to –57…–60°С).

On the coast Arctic seas, due to the development of active winter cyclonic activity here, the minimum temperatures are higher than in the interior. The isogeotherms have an almost latitudinal direction, and the decrease in the average of the absolute annual minima from north to south occurs rather quickly.

On the coast, the isogeotherms repeat the outlines of the shores. The influence of the Aleutian minimum is manifested in the increase in the average of the absolute annual minimums in the coastal zone compared to the inland areas, especially on the southern coast of Primorsky Krai and on Sakhalin. The average of the absolute annual minimums here is –25…–30°С.

The freezing of the soil depends on the magnitude of negative air temperatures in the cold season. The most important factor preventing soil freezing is the presence of snow cover. Its characteristics such as formation time, power, duration of occurrence determine the depth of soil freezing. The late establishment of snow cover contributes to greater freezing of the soil, since in the first half of winter the intensity of soil freezing is greatest and, conversely, the early establishment of snow cover prevents significant freezing of the soil. The influence of the thickness of the snow cover is most pronounced in areas with low air temperatures.

At the same depth of freezing depends on the type of soil, its mechanical composition and humidity.

For example, in northern regions Western Siberia with low and thick snow cover, the depth of soil freezing is less than in more southern and warmer regions with small. A peculiar picture takes place in regions with unstable snow cover (southern regions of the European part of Russia), where it can contribute to an increase in the depth of soil freezing. This is due to the fact that with frequent changes of frost and thaw, an ice crust is formed on the surface of a thin snow cover, the thermal conductivity coefficient of which is several times greater than the thermal conductivity of snow and water. The soil in the presence of such a crust cools and freezes much faster. The presence of vegetation cover contributes to a decrease in the depth of soil freezing, as it retains and accumulates snow.

THERMAL REGIME OF THE UNDERLYING SURFACE AND ATMOSPHERE

The surface directly heated by the sun's rays and giving off heat to the underlying layers and air is called active. The temperature of the active surface, its value and change (daily and annual variation) are determined by the heat balance.

The maximum value of almost all components of the heat balance is observed in the near noon hours. The exception is the maximum heat exchange in the soil, which falls on the morning hours.

The maximum amplitudes of the diurnal variation of the heat balance components are observed in summer, the minimum - in winter. In the diurnal course of surface temperature, dry and devoid of vegetation, on a clear day, the maximum occurs after 13:00, and the minimum occurs around the time of sunrise. Cloudiness disrupts the regular course of surface temperature and causes a shift in the moments of maxima and minima. Humidity and vegetation cover greatly influence the surface temperature. Daytime surface temperature maxima can be + 80°C or more. Daily fluctuations reach 40°. Their value depends on the latitude of the place, time of year, cloudiness, thermal properties of the surface, its color, roughness, vegetation cover, and slope exposure.

The annual course of the temperature of the active layer is different at different latitudes. The maximum temperature in middle and high latitudes is usually observed in June, the minimum - in January. The amplitudes of annual fluctuations in the temperature of the active layer at low latitudes are very small; at middle latitudes on land, they reach 30°. The annual fluctuations in surface temperature in temperate and high latitudes are strongly influenced by snow cover.

It takes time to transfer heat from layer to layer, and the moments of the onset of maximum and minimum temperatures during the day are delayed by every 10 cm by about 3 hours. If the highest temperature on the surface was at about 13:00, at a depth of 10 cm the temperature will reach a maximum at about 16:00, and at a depth of 20 cm - at about 19:00, etc. With successive heating of the underlying layers from the overlying ones, each layer absorbs a certain amount of heat. The deeper the layer, the less heat it receives and the weaker the temperature fluctuations in it. The amplitude of daily temperature fluctuations with depth decreases by 2 times for every 15 cm. This means that if on the surface the amplitude is 16°, then at a depth of 15 cm it is 8°, and at a depth of 30 cm it is 4°.

At an average depth of about 1 m, daily fluctuations in soil temperature "fade out". The layer in which these oscillations practically stop is called the layer constant daily temperature.

The longer the period of temperature fluctuations, the deeper they spread. In the middle latitudes, the layer of constant annual temperature is located at a depth of 19-20 m, in high latitudes at a depth of 25 m. In tropical latitudes, the annual temperature amplitudes are small and the layer of constant annual amplitude is located at a depth of only 5-10 m. and minimum temperatures are delayed by an average of 20-30 days per meter. Thus, if the lowest temperature on the surface was observed in January, at a depth of 2 m it occurs in early March. Observations show that the temperature in the layer of constant annual temperature is close to the average annual air temperature above the surface.

Water, having a higher heat capacity and lower thermal conductivity than land, heats up more slowly and releases heat more slowly. Some of the sun's rays falling on the water surface are absorbed by the uppermost layer, and some of them penetrate to a considerable depth, directly heating some of its layer.

The mobility of water makes heat transfer possible. Due to turbulent mixing, heat transfer in depth occurs 1000 - 10,000 times faster than through heat conduction. When the surface layers of water cool, thermal convection occurs, accompanied by mixing. Daily temperature fluctuations on the surface of the Ocean in high latitudes are on average only 0.1°, in temperate latitudes - 0.4°, in tropical latitudes - 0.5°. The penetration depth of these vibrations is 15-20m. The annual temperature amplitudes on the surface of the Ocean range from 1° in equatorial latitudes to 10.2° in temperate latitudes. Annual temperature fluctuations penetrate to a depth of 200-300 m. The moments of maximum temperature in water bodies are late compared to land. The maximum occurs at about 15-16 hours, the minimum - 2-3 hours after sunrise.

Thermal regime of the lower layer of the atmosphere.

The air is heated mainly not by the sun's rays directly, but due to the transfer of heat to it by the underlying surface (the processes of radiation and heat conduction). The most important role in the transfer of heat from the surface to the overlying layers of the troposphere is played by heat exchange and transfer of latent heat of vaporization. The random movement of air particles caused by its heating of an unevenly heated underlying surface is called thermal turbulence or thermal convection.

If instead of small chaotic moving vortices, powerful ascending (thermals) and less powerful descending air movements begin to predominate, convection is called orderly. Air warming near the surface rushes upward, transferring heat. Thermal convection can only develop as long as the air has a temperature higher than the temperature of the environment in which it rises (an unstable state of the atmosphere). If the temperature of the rising air is equal to the temperature of its surroundings, the rise will stop (an indifferent state of the atmosphere); if the air becomes colder than the environment, it will begin to sink (the steady state of the atmosphere).

With the turbulent movement of air, more and more of its particles, in contact with the surface, receive heat, and rising and mixing, give it to other particles. The amount of heat received by air from the surface through turbulence is 400 times greater than the amount of heat it receives as a result of radiation, and as a result of transfer by molecular heat conduction - almost 500,000 times. Heat is transferred from the surface to the atmosphere along with the moisture evaporated from it, and then released during the condensation process. Each gram of water vapor contains 600 calories of latent heat of vaporization.

In rising air, the temperature changes due to adiabatic process, i.e. without heat exchange with environment, by converting the internal energy of the gas into work and work into internal energy. Since the internal energy is proportional to the absolute temperature of the gas, the temperature changes. The rising air expands, performs work for which it expends internal energy, and its temperature decreases. The descending air, on the contrary, is compressed, the energy spent on expansion is released, and the air temperature rises.

Dry or containing water vapor, but not saturated with them, air, rising, cools adiabatically by 1 ° for every 100 m. Air saturated with water vapor cools by less than 1 ° when rising to 100 m, since condensation occurs in it, accompanied by release heat, partially compensating for the heat spent on expansion.

The amount of cooling of saturated air when it rises by 100 m depends on the air temperature and on atmospheric pressure and varies widely. Unsaturated air, descending, heats up by 1 ° per 100 m, saturated by a smaller amount, since evaporation takes place in it, for which heat is expended. Rising saturated air usually loses moisture during precipitation and becomes unsaturated. When lowered, such air heats up by 1 ° per 100 m.

As a result, the decrease in temperature during the rise is less than its increase during the fall, and the air that has risen and then descended at the same level at the same pressure will have different temperature- the final temperature will be higher than the initial one. Such a process is called pseudoadiabatic.

Since the air is heated mainly from the active surface, the temperature in the lower atmosphere, as a rule, decreases with height. The vertical gradient for the troposphere averages 0.6° per 100 m. It is considered positive if the temperature decreases with height, and negative if it rises. In the lower surface layer of air (1.5-2 m), vertical gradients can be very large.

The increase in temperature with height is called inversion, and a layer of air in which the temperature increases with height, - inversion layer. In the atmosphere, layers of inversion can almost always be observed. At the earth's surface, when it is strongly cooled, as a result of radiation, radiative inversion(radiation inversion) . It appears on clear summer nights and can cover a layer of several hundred meters. In winter, in clear weather, the inversion persists for several days and even weeks. Winter inversions can cover a layer up to 1.5 km.

The relief conditions contribute to the strengthening of the inversion: cold air flows down into the depression and stagnates there. Such inversions are called orographic. Powerful inversions called adventitious, formed when relatively warm air comes to a cold surface, cooling its lower layers. Daytime advective inversions are weakly expressed, at night they are enhanced by radiative cooling. In spring, the formation of such inversions is facilitated by the snow cover that has not yet melted.

Frosts are associated with the phenomenon of temperature inversion in the surface air layer. Freeze - a decrease in air temperature at night to 0 ° and below at a time when the average daily temperatures are above 0 ° (autumn, spring). It may also be that frosts are observed only on the soil when the air temperature above it is above zero.

The thermal state of the atmosphere affects the propagation of light in it. In cases where the temperature changes sharply with height (increases or decreases), there are mirages.

Mirage - an imaginary image of an object that appears above it (upper mirage) or below it (lower mirage). Less common are lateral mirages (the image appears from the side). The cause of mirages is the curvature of the trajectory of light rays coming from an object to the eye of the observer, as a result of their refraction at the boundary of layers with different densities.

The daily and annual temperature variation in the lower troposphere up to a height of 2 km generally reflects the surface temperature variation. With distance from the surface, the amplitudes of temperature fluctuations decrease, and the moments of maximum and minimum are delayed. Daily fluctuations in air temperature in winter are noticeable up to a height of 0.5 km, in summer - up to 2 km.

The amplitude of diurnal temperature fluctuations decreases with increasing latitude. The largest daily amplitude is in subtropical latitudes, the smallest - in polar ones. In temperate latitudes, diurnal amplitudes are different in different times of the year. In high latitudes, the largest daily amplitude is in spring and autumn, in temperate latitudes - in summer.

The annual course of air temperature depends primarily on the latitude of the place. From the equator to the poles, the annual amplitude of air temperature fluctuations increases.

There are four types of annual temperature variation according to the magnitude of the amplitude and the time of the onset of extreme temperatures.

equatorial type characterized by two maxima (after the equinoxes) and two minima (after the solstices). The amplitude over the Ocean is about 1°, over land - up to 10°. The temperature is positive throughout the year.

Tropical type - one maximum (after the summer solstice) and one minimum (after winter solstice). The amplitude over the Ocean is about 5°, on land - up to 20°. The temperature is positive throughout the year.

Moderate type - one maximum (in the northern hemisphere over land in July, over the Ocean in August) and one minimum (in the northern hemisphere over land in January, over the Ocean in February). Four seasons are clearly distinguished: warm, cold and two transitional. The annual temperature amplitude increases with increasing latitude, as well as with distance from the Ocean: on the coast 10 °, away from the Ocean - up to 60 ° and more (in Yakutsk - -62.5 °). The temperature during the cold season is negative.

polar type - winter is very long and cold, summer is short and cool. Annual amplitudes are 25° and more (over land up to 65°). The temperature is negative most of the year. The overall picture of the annual course of air temperature is complicated by the influence of factors, among which the underlying surface is of particular importance. Over the water surface, the annual temperature variation is smoothed out; over land, on the contrary, it is more pronounced. Snow and ice cover greatly reduces annual temperatures. The height of the place above the level of the Ocean, relief, distance from the Ocean, and cloudiness also affect. The smooth course of the annual air temperature is disturbed by disturbances caused by the intrusion of cold or, conversely, warm air. An example can be spring returns of cold weather (cold waves), autumn returns of heat, winter thaws in temperate latitudes.

Distribution of air temperature at the underlying surface.

If the earth's surface were homogeneous, and the atmosphere and hydrosphere were stationary, the distribution of heat over the Earth's surface would be determined only by the influx of solar radiation, and the air temperature would gradually decrease from the equator to the poles, remaining the same at each parallel (solar temperatures). Indeed, the average annual air temperatures are determined by the heat balance and depend on the nature of the underlying surface and the continuous interlatitudinal heat exchange carried out by moving the air and waters of the Ocean, and therefore differ significantly from the solar ones.

The actual average annual air temperatures near the earth's surface are lower in low latitudes, and, on the contrary, higher than solar ones in high latitudes. In the southern hemisphere, the actual average annual temperatures at all latitudes are lower than in the northern. The average air temperature near the earth's surface in the northern hemisphere in January is +8°C, in July +22°C; in the south - +10° C in July, +17° C in January. The average air temperature for the year at the earth's surface is +14 ° C as a whole.

If we mark the highest average annual or monthly temperatures on different meridians and connect them, we get a line thermal maximum, often called the thermal equator. It is probably more correct to consider the parallel (latitudinal circle) with the highest normal average temperatures of the year or any month as the thermal equator. The thermal equator does not coincide with the geographic one and is "shifted" to the north. During the year it moves from 20° N. sh. (in July) to 0° (in January). There are several reasons for the shift of the thermal equator to the north: the predominance of land in the tropical latitudes of the northern hemisphere, the Antarctic cold pole, and, perhaps, the duration of summer matters (summer in the southern hemisphere is shorter).

Thermal belts.

Isotherms are taken beyond the boundaries of thermal (temperature) belts. There are seven thermal zones:

hot belt, located between the annual isotherm + 20 ° of the northern and southern hemispheres; two temperate zones, bounded from the side of the equator by the annual isotherm + 20 °, from the poles by the isotherm + 10 ° of the warm month;

Two cold belts, located between the isotherm + 10 ° and and the warmest month;

Two frost belts located near the poles and bounded by the 0° isotherm of the warmest month. In the northern hemisphere this is Greenland and the space near the north pole, in the southern hemisphere - the area inside the parallel of 60 ° S. sh.

Temperature zones are the basis of climatic zones. Within each belt, there are great variety temperatures depending on the underlying surface. On land, the influence of relief on temperature is very great. The change in temperature with height for every 100 m is not the same in different temperature zones. The vertical gradient in the lower kilometer layer of the troposphere varies from 0° over the ice surface of Antarctica to 0.8° in summer over tropical deserts. Therefore, the method of bringing temperatures to sea level using an average gradient (6°/100 m) can sometimes lead to gross errors. The change in temperature with height is the cause of vertical climatic zonality.

Thermal regime of the atmosphere

local temperature

The total temperature change in the fixed
geographic point, depending on individual
changes in the state of the air, and from advection, are called
local (local) change.
Any meteorological station, which does not change
its position on the earth's surface,
be considered as such a point.
Meteorological instruments - thermometers and
thermographs, fixedly placed in one or another
place, register exactly local changes
air temperature.
A thermometer on a balloon flying in the wind and,
therefore remaining in the same mass
air, shows individual change
temperature in this mass.

Thermal regime of the atmosphere

Air temperature distribution in
space and its change in time
Thermal state of the atmosphere
defined:
1. Heat exchange with the environment
(with underlying surface, adjacent
air masses and outer space).
2. Adiabatic processes
(associated with changes in air pressure,
especially when moving vertically
3. Advection processes
(the transfer of warm or cold air that affects the temperature in
given point)

Heat exchange

Heat transfer paths
1) Radiation
in absorption
air radiation from the sun and the earth
surfaces.
2) Thermal conductivity.
3) Evaporation or condensation.
4) Formation or melting of ice and snow.

Radiative heat transfer path

1. Direct absorption
there is little solar radiation in the troposphere;
it can cause an increase
air temperature by just
about 0.5° per day.
2. Somewhat more important is
loss of heat from the air
longwave radiation.

B = S + D + Ea – Rk – Rd – Ez, kW/m2
where
S - direct solar radiation on
horizontal surface;
D - scattered solar radiation on
horizontal surface;
Ea is the counter radiation of the atmosphere;
Rk and Rd - reflected from the underlying surface
short and long wave radiation;
Ez - long-wave radiation of the underlying
surfaces.

Radiation balance of the underlying surface

B = S + D + Ea– Rk – Rd – Ez, kW/m2
Pay attention to:
Q = S + D This is the total radiation;
Rd is a very small value and is usually not
take into account;
Rk =Q *Ak, where A is the albedo of the surface;
Eef \u003d Ez - Ea
We get:
B \u003d Q (1 - Ak) - Eef

Thermal balance of the underlying surface

B \u003d Lt-f * Mp + Lzh-g * Mk + Qa + Qp-p
where Lt-zh and Lzh-g - specific heat of fusion
and vaporization (condensation), respectively;
Mn and Mk are the masses of water involved in
corresponding phase transitions;
Qa and Qp-p - heat flux into the atmosphere and through
underlying surface to underlying layers
soil or water.

surface and active layer

The temperature regime of the underlying

The underlying surface is
ground surface (soil, water, snow and
etc.), interacting with the atmosphere
in the process of heat and moisture exchange.
The active layer is the layer of soil (including
vegetation and snow cover) or water,
participating in heat exchange with the environment,
to the depth of which the daily and
annual temperature fluctuations.

10. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
In the soil, solar radiation, penetrating
to a depth of tenths of a mm,
converted into heat, which
transmitted to the underlying layers
molecular thermal conductivity.
In water, solar radiation penetrates
depths up to tens of meters, and the transfer
heat to the underlying layers occurs in
turbulent
mixing, thermal
convection and evaporation

11. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
Daily temperature fluctuations
apply:
in water - up to tens of meters,
in the soil - less than a meter
Annual temperature fluctuations
apply:
in water - up to hundreds of meters,
in the soil - 10-20 meters

12. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The heat that comes to the surface of the water during the day and summer penetrates
to a considerable depth and heats a large water column.
The temperature of the upper layer and the very surface of the water
it rises little.
In the soil, the incoming heat is distributed in a thin upper
layer, which thus becomes very hot.
At night and in winter, water loses heat from the surface layer, but
instead of it comes the accumulated heat from the underlying layers.
Therefore, the temperature at the surface of the water decreases
slowly.
On the surface of the soil, the temperature drops when heat is released
fast:
heat accumulated in a thin upper layer quickly leaves it
without replenishment from below.

13. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
During the day and summer, the temperature on the soil surface is higher than the temperature on
water surface; lower at night and in winter.
The daily and annual fluctuations in temperature on the soil surface are greater,
moreover, much more than on the surface of the water.
During the warm season, the water basin accumulates in a fairly thick layer
water, a large amount of heat, which gives off to the atmosphere in a cold
season.
The soil during the warm season gives off most of the heat at night,
which receives during the day, and accumulates little of it by winter.
In the middle latitudes, during the warm half of the year, 1.5-3
kcal of heat per square centimeter of surface.
In cold weather, the soil gives off this heat to the atmosphere. Value ±1.5-3
kcal/cm2 per year is the annual heat cycle of the soil.
Under the influence of snow cover and vegetation in summer, the annual
soil heat circulation decreases; for example, near Leningrad by 30%.
In the tropics, the annual heat turnover is less than in temperate latitudes, since
there are less annual differences in the influx of solar radiation.

14. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The annual heat turnover of large reservoirs is about 20
times more than the annual heat turnover
soil.
The Baltic Sea gives off air in cold weather 52
kcal / cm2 and accumulates the same amount in the warm season.
Annual heat turnover of the Black Sea ±48 kcal/cm2,
As a result of these differences, the air temperature above
lower by sea in summer and higher in winter than over land.

15. Temperature regime of the underlying surface and active layer

The temperature regime of the underlying
surface and active layer
The land heats up quickly and
cools down.
The water heats up slowly and slowly
cools down
(specific heat capacity of water in
3-4 times more soil)
Vegetation reduces the amplitude
diurnal temperature fluctuations
soil surface.
The snow cover protects the soil from
intense heat loss (in winter, the soil
freezes less)

16.

key role in creating
temperature regime of the troposphere
heat exchange plays
air with the earth's surface
by conduction

17. Processes affecting the heat transfer of the atmosphere

Processes affecting heat transfer
atmosphere
1).Turbulence
(mixing
air with disordered
chaotic movement).
2).Thermal
convection
(air transport in vertical
direction that occurs when
heating of the underlying layer)

18. Changes in air temperature

Changes in air temperature
1).
Periodic
2). Non-periodic
Non-periodic changes
air temperature
Associated with advection of air masses
from other parts of the earth
Such changes are frequent and significant in
temperate latitudes,
they are associated with cyclonic
activities, in small
scales - with local winds.

19. Periodic changes in air temperature

Daily and annual temperature changes are
periodic character.
Diurnal Changes
The air temperature changes in
daily course following the temperature
earth's surface, from which
air is heated

20. Daily temperature variation

Daily temperature variation
Multi-annual diurnal curves
temperatures are smooth curves,
similar to sinusoids.
In climatology, it is considered
diurnal change in air temperature,
averaged over many years.

21. on the soil surface (1) and in the air at a height of 2m (2). Moscow (MSU)

The average diurnal temperature variation at the surface
soil (1) and
in the air at a height of 2m (2). Moscow (MSU)

22. Average daily temperature variation

Average daily temperature variation
The temperature on the soil surface has a diurnal variation.
Its minimum is observed approximately half an hour after
sunrise.
By this time, the radiation balance of the soil surface
becomes equal to zero - heat transfer from the upper layer
soil effective radiation is balanced
increased influx of total radiation.
The non-radiative heat exchange at this time is negligible.

23. Average daily temperature variation

Average daily temperature variation
The temperature on the soil surface rises up to 13-14 hours,
when it reaches its maximum in the daily course.
After that, the temperature starts to drop.
The radiation balance in the afternoon hours, however,
remains positive; but
heat transfer in the daytime from the top layer of soil to
atmosphere occurs not only through effective
radiation, but also through increased thermal conductivity, and
also with increased evaporation of water.
The transfer of heat into the depth of the soil also continues.
Therefore, the temperature on the surface of the soil and falls
from 13-14 hours to the morning low.

24.

25. Soil surface temperature

The maximum temperatures at the soil surface are usually higher
than in the air at the height of the meteorological booth. This is clear:
during the day, solar radiation primarily heats the soil, and already
it heats up the air.
In the Moscow region in the summer on the surface of bare soil
temperatures up to + 55 ° are observed, and in deserts - even up to + 80 °.
Nighttime temperature minima, on the contrary, occur at
the soil surface is lower than in the air,
since, first of all, the soil is cooled by effective
radiation, and already from it the air is cooled.
In winter in the Moscow region, night temperatures on the surface (at this time
covered with snow) can fall below -50 °, in summer (except July) - to zero. On the
snow surface in the interior of Antarctica, even the average
the monthly temperature in June is about -70°, and in some cases it can
fall to -90°.

26. Daily temperature range

Daily temperature range
This is the difference between the maximum
and daily minimum temperature.
Daily temperature range
air changes:
by the seasons of the year,
by latitude
depending on the nature
underlying surface,
depending on the terrain.

27. Changes in the daily temperature amplitude (Asut)

Changes

1. In winter, Asut is less than in summer
2. With increasing latitude, A day. decreasing:
at latitude 20 - 30°
on land A days = 12 ° С
at a latitude of 60° A day. = 6°C
3. Open spaces
are characterized by a greater A day. :
for steppes and deserts medium
Asut \u003d 15-20 ° С (up to 30 ° С),

28. Changes in the daily temperature amplitude (Asut)

Changes
daily temperature amplitude (Asut)
4. Proximity of water basins
reduces A day.
5.On convex landforms
(tops and slopes of mountains) A day. smaller,
than on the plain
6. In concave landforms
(hollows, valleys, ravines, etc. And more days.

29. Influence of soil cover on soil surface temperature

Vegetation cover reduces soil cooling at night.
Night radiation occurs mainly with
the surface of the vegetation itself, which will be the most
cool.
The soil under vegetation retains a higher
temperature.
However, during the day, vegetation prevents radiation
heating the soil.
Daily temperature range under vegetation,
thus reduced, and the average daily temperature
lowered.
So, vegetation cover generally cools the soil.
AT Leningrad region soil surface under field
crops may be 15° colder during the daytime than
fallow soil. On average, it is colder per day
exposed soil by 6°, and even at a depth of 5-10 cm remains
a difference of 3-4°.

30. Influence of soil cover on soil surface temperature

Snow cover protects the soil in winter from excessive heat loss.
Radiation comes from the surface of the snow cover itself, and the soil under it
stays warmer than bare soil. At the same time, the daily amplitude
temperatures on the soil surface under the snow drops sharply.
In the middle zone of the European territory of Russia with a snow cover of height
40-50 cm, the temperature of the soil surface under it is 6-7 ° higher than
the temperature of the bare soil, and 10° higher than the temperature on
the surface of the snow cover itself.
Winter soil freezing under snow reaches depths of about 40 cm, and without
snow can extend to depths of more than 100 cm.
So, the vegetation cover in summer reduces the temperature on the soil surface, and
snow cover in winter, on the contrary, increases it.
The combined effect of vegetation cover in summer and snow cover in winter reduces
annual amplitude of temperature on the soil surface; this reduction is
about 10° compared to bare soil.

31. Distribution of heat deep into the soil

The greater the density and moisture content of the soil, the
the better it conducts heat, the faster
spread deeper and deeper
temperature fluctuations penetrate.
Regardless of soil type, the oscillation period
temperature does not change with depth.
This means that not only on the surface, but also on
depths remains a daily course with a period of 24
hours between each two consecutive
highs or lows
and an annual course with a period of 12 months.

32. Distribution of heat deep into the soil

The oscillation amplitudes decrease with depth.
Increasing depth in arithmetic progression
leads to a progressive decrease in amplitude
geometric.
So, if on the surface the daily amplitude is 30°, and
at a depth of 20 cm 5 °, then at a depth of 40 cm it will be narrower
less than 1°.
At some relatively shallow depth, the daily
amplitude decreases so much that it becomes
practically equal to zero.
At this depth (about 70-100 cm, in different cases
different) begins a layer of constant daily
temperature.

33. Daily variation of temperature in the soil at different depths from 1 to 80 cm. Pavlovsk, May.

34. Annual temperature fluctuations

The amplitude of annual temperature fluctuations decreases from
depth.
However, annual fluctuations extend to a larger
depth, which is quite understandable: for their distribution
there is more time.
The amplitudes of annual fluctuations decrease almost to
zero at a depth of about 30 m in polar latitudes,
about 15-20 m in middle latitudes,
about 10 m in the tropics
(where and on the soil surface the annual amplitudes are smaller,
than in mid-latitudes).
At these depths begins, a layer of constant annual
temperature.

35.

The timing of the maximum and minimum temperatures
both in the daily and in the annual course they lag with depth
in proportion to her.
This is understandable, since it takes time for the heat to spread through
depth.
Daily extremes for every 10 cm of depth are delayed by
2.5-3.5 hours.
This means that at a depth of, for example, 50 cm, the daily maximum
seen after midnight.
Annual highs and lows are 20-30 days late by
every meter of depth.
So, in Kaliningrad at a depth of 5 m, the minimum temperature
observed not in January, as on the soil surface, but in May,
maximum - not in July, but in October

36. Annual variation of temperature in the soil at different depths from 3 to 753 cm in Kaliningrad.

37. Temperature distribution in the soil vertically in different seasons

In summer, the temperature drops from the soil surface to the depth.
Grows in winter.
In the spring, it first grows, and then decreases.
In autumn, it first decreases and then grows.
Changes in temperature in the soil with depth during the day or year can be represented with
using an isopleth chart.
The x-axis represents time in hours or months of the year.
The y-axis is the depth in the soil.
Each point on the graph corresponds to a certain time and a certain depth. On the
graph plots average temperatures at different depths at different hours or
months.
After drawing isolines connecting points with equal temperatures,
for example, every degree or every 2 degrees, we get a family
thermal isopleth.
According to this graph, you can determine the temperature value for any moment of the day.
or day of the year and for any depth within the graph.

38. Isopleths of the annual temperature variation in the soil in Tbilisi

Isoplets of the annual temperature variation in the soil in
Tbilisi

39. Daily and annual course of temperature on the surface of reservoirs and in the upper layers of water

Heating and cooling spreads in water bodies for more than
thick layer than in the soil, and in addition having a greater
heat capacity than soil.
As a result of this change in temperature at the surface of the water
very small.
Their amplitude is of the order of tenths of a degree: about 0.1-
0.2° in temperate latitudes,
about 0.5° in the tropics.
In the southern seas of the USSR, the daily temperature amplitude is greater:
1-2°;
on the surface of large lakes in temperate latitudes even more:
2-5°.
Diurnal fluctuations in ocean surface water temperature
have a maximum of about 15-16 hours and a minimum after 2-3 hours
after sunrise.

40. Daily variation of temperature at the sea surface (solid curve) and at a height of 6 m in the air (dashed curve) in a tropical

Atlantic

41. Daily and annual course of temperature on the surface of reservoirs and in the upper layers of water

Annual amplitude of surface temperature fluctuations
ocean much more than the daily.
But it is less than the annual amplitude on the soil surface.
In the tropics, it is about 2-3 °, under 40 ° N. sh. about 10 °, and at 40 ° S.
sh. around 5°.
On inland seas and deep-sea lakes,
significantly large annual amplitudes - up to 20° or more.
Both daily and annual fluctuations propagate in water
(also, of course, belatedly) to greater depths than in soil.
Daily fluctuations are found in the sea at depths up to 15
20 m and more, and annual - up to 150-400 m.

42. Daily variation of air temperature near the earth's surface

Air temperature changes daily
following the temperature of the earth's surface.
As the air is heated and cooled by
the earth's surface, the amplitude of the diurnal variation
the temperature in the meteorological booth is lower,
than on the soil surface, on average about
by one third.

43. Daily variation of air temperature near the earth's surface

An increase in air temperature begins with an increase in
soil temperature (15 minutes later) in the morning,
after sunrise. At 13-14 hours the soil temperature,
starts to drop.
At 14-15 hours it equalizes with the air temperature;
From now on, with a further drop in temperature
the soil starts to drop and the air temperature.
Thus, the minimum in the daily course of temperature
air at the earth's surface falls on time
shortly after sunrise,
and a maximum of 14-15 hours.

44. Daily variation of air temperature near the earth's surface

The daily course of air temperature is quite correct
manifests itself only in stable clear weather.
It seems even more logical on average from a large
number of observations: long-term diurnal curves
temperature - smooth curves, similar to sinusoids.
But on some days, the diurnal variation of air temperature can
be very wrong.
It depends on changes in cloudiness that change the radiative
conditions on the earth's surface, as well as from advection, i.e. from
inflow of air masses with a different temperature.
As a result of these reasons, the temperature minimum may shift
even during the daytime, and a maximum - at night.
The diurnal variation of temperature may disappear altogether or the curve
diurnal change will take a complex and irregular form.

45. Daily variation of air temperature near the earth's surface

The regular diurnal course is overlapped or masked
non-periodic temperature changes.
For example, in Helsinki in January there are 24%
the probability that the daily temperature maximum
be between midnight and one in the morning, and
only 13% chance that it will fall on
time interval from 12 to 14 hours.
Even in the tropics, where non-periodic temperature changes are weaker than in temperate latitudes, the maximum
temperatures are in the afternoon
only in 50% of all cases.

46. ​​Daily variation of air temperature near the earth's surface

In climatology, the diurnal variation is usually considered
air temperature averaged over a long period.
In such an average daily course, non-periodic changes
temperatures that fall more or less evenly across
all hours of the day cancel each other out.
As a result, the long-term diurnal variation curve has
simple character close to sinusoidal.
For example, consider the daily variation of air temperature in
Moscow in January and July, calculated by multi-year
data.
Multi-year average temperature for every hour
January or July days, and then according to the obtained average
hourly values ​​were constructed long-term curves
daily course for January and July.

47. Daily course of air temperature in Moscow in January and July. The figures indicate the average monthly temperatures of January and July.

48. Daily changes in the amplitude of air temperature

The daily amplitude of air temperature varies by season,
latitude, as well as depending on the nature of the soil and
terrain.
In winter, it is less than in summer, as well as the amplitude
underlying surface temperature.
With increasing latitude, the daily temperature amplitude
air decreases as the midday height of the sun decreases
over the horizon.
Under latitudes of 20-30 ° on land, the annual average daily
temperature amplitude about 12°,
under latitude 60° about 6°,
under latitude 70° only 3°.
In the highest latitudes where the sun does not rise or
comes many days in a row, regular daily course
no temperature at all.

49. Influence of the nature of the soil and soil cover

The greater the diurnal range of temperature itself
soil surface, the greater the daily amplitude
air temperature above it.
In the steppes and deserts, the average daily amplitude
reaches 15-20°, sometimes 30°.
It is smaller above the abundant vegetation cover.
The proximity of water sources also affects the diurnal amplitude.
basins: in coastal areas it is lowered.

50. Relief influence

On convex landforms (on the peaks and on
slopes of mountains and hills) daily temperature range
air is reduced in comparison with the flat terrain.
In concave landforms (in valleys, ravines and hollows)
increased.
The reason is that on convex landforms
air has a reduced area of ​​contact with
underlying surface and is quickly removed from it, being replaced
new masses of air.
In concave landforms, the air heats up more strongly from
surface and stagnates more during the daytime, and at night
cools more strongly and flows down the slopes. But in narrow
gorges, where both the influx of radiation and effective radiation
reduced, diurnal amplitudes are less than in wide
valleys

51. Influence of the seas and oceans

Small diurnal temperature amplitudes on the surface
seas also have small diurnal amplitudes
air temperature over the sea.
However, these latter are still higher than the daily
amplitudes on the sea surface itself.
Diurnal amplitudes on the surface of the open ocean
measured only in tenths of a degree;
but in the lower layer of air above the ocean they reach 1 -
1.5°),
and more over inland seas.
The temperature amplitudes in the air are increased because
they are influenced by the advection of air masses.
Direct absorption also plays a role.
solar radiation by the lower layers of air during the day and
radiation from them at night.

52. Change in daily temperature amplitude with height

Daily temperature fluctuations in the atmosphere extend to
a more powerful layer than the diurnal fluctuations in the ocean.
At an altitude of 300 m above land, the amplitude of the daily temperature variation
about 50% of the amplitude at the earth's surface, and the extreme values
temperatures come 1.5-2 hours later.
At an altitude of 1 km, the daily temperature range over land is 1-2°,
at a height of 2-5 km 0.5-1 °, and the daytime maximum shifts to
evening.
Over the sea, the daily temperature amplitude slightly increases with
high in the lower kilometers, but still remains small.
Small diurnal temperature fluctuations are detected even
in the upper troposphere and in the lower stratosphere.
But there they are already determined by the processes of absorption and emission
radiation by air, and not by the influences of the earth's surface.

53. The influence of the terrain

In the mountains, where the influence of the underlying surface is greater than on
corresponding altitudes in free atmosphere, daily
amplitude decreases with height more slowly.
On individual mountain peaks, at altitudes of 3000 m and more,
the daily amplitude can still be 3-4°.
On high, vast plateaus, the diurnal temperature range
air of the same order as in the lowlands: absorbed radiation
and the effective radiation is large here, as is the surface
contact of air with soil.
The daily range of air temperature at Murghab station at
In the Pamirs, the annual average is 15.5°, while in Tashkent it is 12°.

54.

55. Radiation of the earth's surface

Top layers of soil and water, snowy
cover and vegetation themselves radiate
longwave radiation; this earthly
radiation is often referred to as intrinsic
radiation from the earth's surface.

56. Radiation of the earth's surface

Absolute temperatures of the earth's surface
are between 180 and 350°.
At these temperatures, the emitted radiation
practically lies within
4-120 microns,
and the maximum of its energy falls on the wavelengths
10-15 microns.
Therefore, all this radiation
infrared, invisible to the eye.

57.

58. Atmospheric radiation

The atmosphere heats up by absorbing both solar radiation
(although in a relatively small proportion, about 15% of its total
amount coming to the Earth), and its own
radiation from the earth's surface.
In addition, it receives heat from the earth's surface.
by conduction of heat, as well as by evaporation and
subsequent condensation of water vapor.
Being heated, the atmosphere radiates itself.
Just like the earth's surface, it radiates an invisible
infrared radiation in the same range
wavelengths.

59. Counter radiation

Most (70%) of atmospheric radiation comes from
the earth's surface, the rest goes into the world
space.
Atmospheric radiation reaching the earth's surface is called counterradiation.
Oncoming because it is directed towards
self-radiation of the earth's surface.
The earth's surface absorbs this counter radiation
almost entirely (by 90-99%). Thus, it is
for the earth's surface an important source of heat in
addition to the absorbed solar radiation.

60. Counter radiation

Counter radiation increases with increasing cloudiness,
because the clouds themselves radiate strongly.
For flat stations of temperate latitudes, the average
counter radiation intensity (for each
square centimeter of horizontal earth
surface per minute)
about 0.3-0.4 cal,
at mountain stations - about 0.1-0.2 cal.
This is a decrease in counter radiation with height
due to the decrease in water vapor content.
The largest counter radiation is at the equator, where
the atmosphere is the hottest and richest in water vapor.
At the equator 0.5-0.6 cal/cm2 min on average,
In polar latitudes up to 0.3 cal/cm2 min.

61. Counter radiation

The main substance in the atmosphere that absorbs
terrestrial radiation and sending oncoming
radiation, is water vapor.
It absorbs infrared radiation in a large
spectral region - from 4.5 to 80 microns, with the exception of
interval between 8.5 and 11 microns.
With an average content of water vapor in the atmosphere
radiation with wavelengths from 5.5 to 7.0 microns or more
absorbed almost completely.
Only in the range of 8.5-11 microns terrestrial radiation
passes through the atmosphere into outer space.

62.

63.

64. Effective Radiation

The counter radiation is always somewhat less than the terrestrial one.
At night, when there is no solar radiation, the earth's surface comes
only counter radiation.
The earth's surface loses heat due to the positive difference between
own and counter radiation.
The difference between the earth's own radiation
surface and counter radiation of the atmosphere
called effective radiation

65. Efficient Radiation

Effective radiation is
net loss of radiant energy, and
hence the heat from the earth's surface
at night

66. Effective Radiation

With increasing cloudiness, increasing
counter radiation, effective radiation
decreases.
In cloudy weather, effective radiation
much less than in clear;
In cloudy weather less and night
cooling of the earth's surface.

67. Effective Radiation

Effective radiation, of course,
also exists during the day.
But during the day it overlaps or partially
compensated by the absorbed solar
radiation. Therefore, the earth's surface
warmer during the day than at night, as a result of which,
among other things, and effective radiation
more during the day.

68. Effective Radiation

Absorbing terrestrial radiation and sending oncoming
radiation to the earth's surface, atmosphere
most reduces the cooling of the latter in
night time.
During the day, it does little to prevent the heating of the earth.
surface by solar radiation.
This is the influence of the atmosphere on the thermal regime of the earth
surface is called the greenhouse effect.
due to external analogy with the action of glasses
greenhouses.

69. Effective Radiation

In general, the earth's surface in medium
latitudes loses effective
radiation about half that
the amount of heat she receives
from absorbed radiation.

70. Radiation balance of the earth's surface

The difference between the absorbed radiation and the radiation balance of the earth's surface In the presence of snow cover, the radiation balance
goes to positive values ​​only at height
the sun is about 20-25 °, since with a large snow albedo
its absorption of total radiation is small.
During the day, the radiation balance increases with increasing altitude.
sun and decreases with its decrease.
At night, when there is no total radiation,
the negative radiation balance is
effective radiation
and therefore changes little during the night, unless
cloud conditions remain the same.

76. Radiation balance of the earth's surface

Mean noon values
radiation balance in Moscow:
in summer with a clear sky - 0.51 kW / m2,
in winter with a clear sky - 0.03 kW / m2
summer under average conditions
cloudiness - 0.3 kW / m2,
winter under average conditions
cloud cover is about 0 kW/m2.

77.

78.

79. Radiation balance of the earth's surface

The radiation balance is determined by a balance meter.
It has one blackened receiving plate
pointing up towards the sky
and the other - down to the earth's surface.
The difference in plate heating allows
determine the value of the radiation balance.
At night, it is equal to the value of the effective
radiation.

80. Radiation into world space

Most of the radiation from the earth's surface
absorbed in the atmosphere.
Only in the wavelength range of 8.5-11 microns passes through
atmosphere in the world space.
This outgoing amount is only 10%, of
influx of solar radiation to the boundary of the atmosphere.
But, in addition, the atmosphere itself radiates into the world
space about 55% of the energy from the incoming
solar radiation,
i.e., several times larger than the earth's surface.

81. Radiation into the world space

Radiation from the lower layers of the atmosphere is absorbed in
its overlying layers.
But, as you move away from the earth's surface, the content
water vapor, the main absorber of radiation,
decreases, and an increasingly thicker layer of air is needed,
to absorb radiation coming from
the underlying layers.
Starting from some height of water vapor in general
not enough to absorb all the radiation,
coming from below, and from these upper layers part
atmospheric radiation will go into the world
space.
Calculations show that the most strongly radiating in
Space layers of the atmosphere lie at altitudes of 6-10 km.

82. Radiation into the world space

Long-wave radiation of the earth's surface and
atmosphere going into space is called
outgoing radiation.
It is about 65 units, if we take for 100 units
influx of solar radiation into the atmosphere. Together with
reflected and scattered shortwave solar
radiation that escapes the atmosphere in
an amount of about 35 units (planetary albedo of the Earth),
this outgoing radiation compensates for the influx of solar
radiation to the earth.
Thus, the Earth, along with the atmosphere, loses
as much radiation as it receives, i.e.
is in a state of radiant (radiation)
balance.

83. Radiation balance

Qincoming = Qoutput
Qincoming \u003d I * S projections * (1-A)
σ
1/4
T =
Q flow = S earth * * T4
T=
0
252K

84. Physical constants

I - Solar constant - 1378 W/m2
R(Earth) - 6367 km.
A - the average albedo of the Earth - 0.33.
Σ - Stefan-Boltzmann constant -5.67 * 10 -8
W/m2K4

B - glad. Balance, P- heat received at molek. heat exchange with the surface Earth. Len - received from condens. moisture.

Heat balance of the atmosphere:

B - glad. Balance, P- heat costs per molecule. heat exchange with the lower layers of the atmosphere. Gn - heat costs per molecule. heat exchange with the lower soil layers Len is the heat consumption for moisture evaporation.

Rest on the map

10) Thermal regime of the underlying surface:

The surface that is directly heated by the sun's rays and gives off heat to the underlying layers of soil and air is called the active surface.

The temperature of the active surface is determined by the heat balance.

The daily temperature course of the active surface reaches a maximum of 13 hours, the minimum temperature is around the moment of sunrise. Maxim. and min. temperatures during the day can shift due to cloudiness, soil moisture and vegetation cover.

The temperature value depends on:

1. From the geographic latitude of the area
2. From the time of year
3. About cloudiness
4. From the thermal properties of the surface
5. From vegetation
6. From exposure slopes

In the annual course of temperatures, the maximum in medium and high meal in the northern hemisphere is observed in July, and the minimum in January. At low latitudes, the annual amplitudes of temperature fluctuations are small.

The temperature distribution in depth depends on the heat capacity and its thermal conductivity. It takes time to transfer heat from layer to layer, for every 10 meters of successive heating of the layers, each layer absorbs part of the heat, so the deeper the layer, the less heat it receives, and the less temperature fluctuation in it. on average, at a depth of 1 m, daily fluctuations in temperature stop, annual fluctuations in low latitudes end at a depth of 5-10 m. in middle latitudes up to 20 m. in high 25 m. The layer of constant temperatures, the layer of soil which is located between the active surface and the layer of constant temperatures, is called the active layer.

Distribution features. Fourier was involved in the temperature in the earth, he formulated the laws of heat propagation in the soil, or "Fourier's laws":

1))). The greater the density and moisture of the soil, the better it conducts heat, the faster the distribution in depth and the deeper the heat penetrates. Temperature does not depend on soil types. The oscillation period does not change with depth

2))). An increase in depth in an arithmetic progression leads to a decrease in the temperature amplitude in a geometric progression.

3))) The timing of the onset of maximum and minimum temperatures, both in the daily and in the annual course of temperatures, decays with depth in proportion to the increase in depth.

11.Heating of the atmosphere. Advection.. The main source of life and many natural processes on Earth is the radiant energy of the Sun, or the energy of solar radiation. Every minute, 2.4 x 10 18 cal of solar energy enters the Earth, but this is only one two-billionth of it. Distinguish between direct radiation (directly coming from the Sun) and diffuse (radiated by air particles in all directions). Their totality, arriving on a horizontal surface, is called total radiation. The annual value of the total radiation depends primarily on the angle of incidence of the sun's rays on the earth's surface (which is determined by geographic latitude), on the transparency of the atmosphere and the duration of illumination. In general, the total radiation decreases from the equatorial-tropical latitudes towards the poles. It is maximum (about 850 J / cm 2 per year, or 200 kcal / cm 2 per year) - in tropical deserts, where direct solar radiation is most intense due to the high altitude of the Sun and a cloudless sky.

The sun mainly heats the surface of the Earth, it heats the air from it. Heat is transferred to the air by radiation and conduction. The air heated from the earth's surface expands and rises - this is how convective currents are formed. The ability of the earth's surface to reflect the sun's rays is called albedo: snow reflects up to 90% of solar radiation, sand - 35%, and the wet soil surface about 5%. That part of the total radiation that remains after spending it on reflection and on thermal radiation from the earth's surface is called the radiation balance (residual radiation). The radiation balance regularly decreases from the equator (350 J/cm 2 per year, or about 80 kcal/cm 2 per year) to the poles, where it is close to zero. From the equator to the subtropics (forties), the radiation balance throughout the year is positive, in temperate latitudes in winter it is negative. The air temperature also decreases towards the poles, which is well reflected by isotherms - lines connecting points with the same temperature. The isotherms of the warmest month are the boundaries of seven thermal zones. The hot zone is limited by isotherms +20 °c to +10 °c, two moderate poles extend, from +10 °c to 0 °c - cold. Two subpolar frost regions are outlined by a zero isotherm - here ice and snow practically do not melt. The mesosphere extends up to 80 km, in which the air density is 200 times less than at the surface, and the temperature again decreases with height (up to -90 °). This is followed by the ionosphere consisting of charged particles (auroras occur here), its other name is the thermosphere - this shell received due to extremely high temperatures (up to 1500 °). Layers above 450 km, some scientists call the exosphere, from here particles escape into outer space.

The atmosphere protects the Earth from excessive overheating during the day and cooling at night, protects all life on Earth from ultraviolet solar radiation, meteorites, corpuscular streams and cosmic rays.

advection- the movement of air in the horizontal direction and the transfer with it of its properties: temperature, humidity, and others. In this sense one speaks, for example, of the advection of heat and cold. The advection of cold and warm, dry and humid air masses plays an important role in meteorological processes and thus affects the state of the weather.

Convection- the phenomenon of heat transfer in liquids, gases or granular media by flows of the substance itself (it does not matter if it is forced or spontaneous). There is a so-called. natural convection, which occurs spontaneously in a substance when it is heated unevenly in a gravitational field. With such convection, the lower layers of matter heat up, become lighter and float up, while the upper layers, on the contrary, cool down, become heavier and sink down, after which the process repeats again and again. Under certain conditions, the mixing process self-organizes into the structure of individual vortices and a more or less regular lattice of convection cells is obtained.

Distinguish between laminar and turbulent convection.

Natural convection owes many atmospheric phenomena, including the formation of clouds. Thanks to the same phenomenon, tectonic plates move. Convection is responsible for the appearance of granules on the Sun.

adiabatic process- a change in the thermodynamic state of air that proceeds adiabatically (isentropically), that is, without heat exchange between it and the environment (the earth's surface, space, other air masses).

12. Temperature inversions in the atmosphere, an increase in air temperature with height instead of the usual for troposphere her decline. Temperature inversions are also found near the earth's surface (surface Temperature inversions), and in a free atmosphere. Surface Temperature inversions most often formed on calm nights (in winter, sometimes during the day) as a result of intense heat radiation from the earth's surface, which leads to cooling of both itself and the adjacent air layer. Surface thickness Temperature inversions is tens to hundreds of meters. The increase in temperature in the inversion layer ranges from tenths of degrees to 15-20 °C and more. The most powerful winter ground Temperature inversions in Eastern Siberia and Antarctica.
In the troposphere, above the ground layer, Temperature inversions more often they are formed in anticyclones due to air settling, accompanied by its compression, and, consequently, heating (settling inversion). In zones atmospheric fronts Temperature inversions are created as a result of the inflow of warm air onto the underlying cold one. Upper atmosphere (stratosphere, mesosphere, thermosphere) Temperature inversions due to strong absorption of solar radiation. So, at altitudes from 20-30 to 50-60 km situated Temperature inversions associated with the absorption of solar ultraviolet radiation by ozone. At the base of this layer, the temperature is from -50 to -70°C, at its upper boundary it rises to -10 - +10°C. Powerful Temperature inversions, starting at an altitude of 80-90 km and extending for hundreds km up, is also due to the absorption of solar radiation.
Temperature inversions are the delaying layers in the atmosphere; they prevent the development of vertical air movements, as a result of which water vapor, dust, and condensation nuclei accumulate under them. This favors the formation of layers of haze, fog, clouds. Due to the anomalous refraction of light in Temperature inversions sometimes arise mirages. AT Temperature inversions are also formed atmospheric waveguides, favorable to the distant propagation of radio waves.

13.Types of annual temperature variation.G annual course of air temperature in different geographical areas varied. According to the magnitude of the amplitude and the time of onset of extreme temperatures, four types of annual variation in air temperature are distinguished.

equatorial type. In the equatorial zone, two

maximum temperature - after the spring and autumn equinox, when

the sun over the equator at noon is at its zenith, and two minima are after

winter and summer solstices, when the sun is at its lowest

height. The amplitudes of the annual variation are small here, which is explained by the small

change in heat gain during the year. Over the oceans, the amplitudes are

about 1 °С, and over the continents 5-10 °С.

Tropical type. In tropical latitudes, there is a simple annual cycle

air temperature with a maximum after summer and a minimum after winter

solstice. Amplitudes of the annual cycle with distance from the equator

increase in winter. The average amplitude of the annual cycle over the continents

is 10 - 20 ° C, over the oceans 5 - 10 ° C.

Temperate type. In temperate latitudes, there is also an annual variation

temperatures with a maximum after the summer and a minimum after the winter

solstice. Over the continents of the northern hemisphere, the maximum

average monthly temperature observed in July, over the seas and coasts - in

August. Annual amplitudes increase with latitude. over the oceans and

coasts, they average 10-15 ° C, and at a latitude of 60 ° reach

polar type. The polar regions are characterized by prolonged cold

in winter and relatively short cool summers. Annual amplitudes over

the ocean and the coasts of the polar seas are 25-40 ° C, and on land

exceed 65 ° C. The maximum temperature is observed in August, the minimum - in

The considered types of annual variation of air temperature are revealed from

long-term data and represent regular periodic fluctuations.

In some years, under the influence of intrusions of warm and cold masses,

deviations from the given types.

14. Characteristics of air humidity.

Air humidity, the content of water vapor in the air; one of the most essential characteristics of weather and climate. V. in. is of great importance in certain technological processes, the treatment of a number of diseases, the storage of works of art, books, etc.

V.'s characteristics in. serve: 1) elasticity (or partial pressure) e water vapor, expressed in n/m 2 (in mmHg Art. or in mb), 2) absolute humidity a - the amount of water vapor in g/m 3; 3) specific humidity q- the amount of water vapor in G on the kg humid air; 4) mixture ratio w, determined by the amount of water vapor in G on the kg dry air; 5) relative humidity r- elasticity ratio e water vapor contained in the air to maximum elasticity E water vapor saturating the space above a flat surface of pure water (saturation elasticity) at a given temperature, expressed in%; 6) moisture deficiency d- the difference between the maximum and actual elasticity of water vapor at a given temperature and pressure; 7) dew point τ - the temperature that air will take if it is cooled isobarically (at constant pressure) to the state of saturation of the water vapor in it.

V. in. earth's atmosphere fluctuates over a wide range. Thus, near the earth's surface, the content of water vapor in the air averages from 0.2% by volume in high latitudes to 2.5% in the tropics. Accordingly, the vapor pressure e in polar latitudes in winter less than 1 mb(sometimes only hundredths mb) and in summer below 5 mb; in the tropics it rises to 30 mb, and sometimes more. In subtropical deserts e lowered to 5-10 mb (1 mb = 10 2 n/m 2). Relative Humidity r very high in the equatorial zone (average annual up to 85% or more), as well as in polar latitudes and in winter inside the continents of middle latitudes - here due to low air temperature. In summer, monsoon regions are characterized by high relative humidity (India - 75-80%). Low values r are observed in subtropical and tropical deserts and in winter in monsoon regions (up to 50% and below). With height r, a and q are rapidly decreasing. At a height of 1.5-2 km vapor pressure is on average half that of the earth's surface. To the troposphere (lower 10-15 km) accounts for 99% of the water vapor in the atmosphere. On average over each m 2 of the earth's surface in the air contains about 28.5 kg water vapor.

The daily course of vapor pressure over the sea and in coastal areas is parallel to the daily course of air temperature: the moisture content increases during the day with an increase in evaporation. It's the same daily routine. e in the central regions of the continents during the cold season. A more complex diurnal variation with two maxima - in the morning and in the evening - is observed in the depths of the continents in summer. Daily variation of relative humidity r is inverse to the diurnal variation of temperature: in the daytime with an increase in temperature and, consequently, with an increase in saturation elasticity E relative humidity decreases. The annual course of vapor pressure is parallel to the annual course of air temperature; Relative humidity changes with the annual course inversely to temperature. V. in. measured hygrometers and psychrometers.

15. Evaporation- the physical process of the transition of a substance from a liquid state to a gaseous state (vapor) from the surface of a liquid. The evaporation process is the reverse of the condensation process (transition from vapor to liquid).

The evaporation process depends on the intensity of the thermal motion of the molecules: the faster the molecules move, the faster the evaporation occurs. Besides, important factors that affect the evaporation process are the rate of external (with respect to the substance) diffusion, as well as the properties of the substance itself. Simply put, with wind, evaporation occurs much faster. As for the properties of the substance, then, for example, alcohol evaporates much faster than water. An important factor is also the surface area of ​​the liquid from which evaporation occurs: from a narrow decanter, it will occur more slowly than from a wide plate.

Evaporation- the maximum possible evaporation under given meteorological conditions from a sufficiently moistened underlying surface, that is, under conditions of an unlimited supply of moisture. Evaporation is expressed in millimeters of evaporated water and is very different from actual evaporation, especially in the desert, where evaporation is close to zero and evaporation is 2000 mm per year or more.

16.condensation and sublimation. Condensation consists in changing the shape of water from its gaseous state(water vapor) into liquid water or ice crystals. Condensation mainly occurs in the atmosphere when warm air rises, cools and loses its ability to contain water vapor (a state of saturation). As a result, excess water vapor condenses in the form of drop clouds. The upward movement that clouds form can be caused by convection in unsustainably stratified air, convergence associated with cyclones, rising air by fronts, and rising over elevated topography such as mountains.

Sublimation- the formation of ice crystals (frost) immediately from water vapor without passing them into water or their rapid cooling below 0 ° C at a time when the air temperature is still above this radiative cooling, which happens on quiet clear nights in the cold part of the year.

Dew- view precipitation formed on the surface of the earth, plants, objects, roofs of buildings, cars and other objects.

Due to the cooling of the air, water vapor condenses on objects near the ground and turns into water droplets. This usually happens at night. In desert regions, dew is an important source of moisture for vegetation. A sufficiently strong cooling of the lower layers of air occurs when, after sunset, the surface of the earth is rapidly cooled by thermal radiation. Favorable conditions for this are a clear sky and a surface covering that easily gives off heat, such as grass. Especially strong dew formation occurs in tropical regions, where the air in the surface layer contains a lot of water vapor and, due to the intense nighttime thermal radiation of the earth, is significantly cooled. Frost forms at low temperatures.

The air temperature below which dew falls is called the dew point.

Frost- a type of precipitation, which is a thin layer of ice crystals formed from atmospheric water vapor. It is often accompanied by fog. Just like dew, it is formed due to cooling of the surface to negative temperatures, lower than the air temperature, and desublimation of water vapor on the surface, which has cooled below 0 ° C. In terms of shape, frost particles resemble snowflakes, but differ from them in less regularity, since they originate in less equilibrium conditions, on the surface of some objects.

frost- type of precipitation.

Hoarfrost is ice deposits on thin and long objects (tree branches, wires) in fog.