How does temperature change with altitude in the mountains. Why do you think the air temperature decreases with altitude? Temperature fluctuations in different layers
Troposphere
Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass of atmospheric air and about 90% of all water vapor present in the atmosphere. In the troposphere, turbulence and convection are highly developed, clouds appear, cyclones and anticyclones develop. Temperature decreases with altitude with an average vertical gradient of 0.65°/100 m
tropopause
The transitional layer from the troposphere to the stratosphere, the layer of the atmosphere in which the decrease in temperature with height stops.
Stratosphere
The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from -56.5 to 0.8 °C (the upper stratosphere layer or inversion region) are typical. Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere.
Stratopause
The boundary layer of the atmosphere between the stratosphere and the mesosphere. There is a maximum in the vertical temperature distribution (about 0 °C).
Mesosphere
The mesosphere begins at an altitude of 50 km and extends up to 80-90 km. The temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc., cause atmospheric luminescence.
mesopause
Transitional layer between mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).
Karman Line
Altitude above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. The Karmana line is located at an altitude of 100 km above sea level.
Earth's atmosphere boundary
Thermosphere
The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values of the order of 1500 K, after which it remains almost constant up to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, air is ionized (“polar lights”) - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity, there is a noticeable decrease in the size of this layer.
Thermopause
The region of the atmosphere above the thermosphere. In this region, the absorption of solar radiation is insignificant and the temperature does not actually change with height.
Exosphere (scattering sphere)
Atmospheric layers up to a height of 120 km
Exosphere - scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and hence its particles leak into interplanetary space (dissipation).
Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular masses, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200–250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.
At an altitude of about 2000-3500 km, the exosphere gradually passes into the so-called near space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is composed of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.
The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.
Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity has an effect on the separation of gases, since their mixing at such a height is negligible. Hence follows the variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere, called the homosphere. The boundary between these layers is called the turbopause and lies at an altitude of about 120 km.
The air temperature in the troposphere as a whole decreases by an average of 0.6 °C for every 100 m of altitude. However, in the lower layer (up to 100-150 m) the temperature distribution can be different: it can increase, remain constant or decrease.
When the temperature decreases with distance from the active surface, such a distribution, as noted in Sec. 3.4, called insolation. In the air over land, this happens in the warm season during the daytime in clear weather. Insolation creates favorable conditions for the development of thermal convection (see Section 4.1) and the formation of clouds.
When the air temperature does not change with height, this condition is called "isotherm". Temperature isotherm is observed in cloudy, calm weather.
If the air temperature increases with distance from the surface, this temperature distribution is called inversion.
Depending on the conditions for the formation of inversions in the surface layer of the atmosphere, they are divided into radiative and advective.
Radiation inversions arise during radiation cooling of the active surface. Such inversions during the warm period of the year are formed at night, and in winter they are also observed during the day. Therefore, radiative inversions are divided into night (summer) and winter ones.
Night inversions are established in clear calm weather after the radiation balance passes through zero 1.0 ... 1.5 hours before sunset. During the night, they intensify and reach their maximum power before sunrise. After sunrise, the active surface and the air warm up, which destroys the inversion. The height of the inversion layer is most often several tens of meters, but under certain conditions (for example, in closed valleys surrounded by significant elevations) it can reach 200 m or more. This is facilitated by the flow of cooled air from the slopes into the valley. Cloudiness weakens the inversion, and the wind speed is more
2.5...3.0 m/s destroys it. Under the canopy of dense herbage, sowing, as well as the garden in summer, inversions are also observed during the day (Fig. 4.4, b).
Night radiation inversions in spring and autumn, and in some places in summer, can cause a decrease in soil and air surface temperatures to negative values(frost), which causes damage to crop plants.
Winter inversions occur in clear, calm weather under short day conditions, when cooling of the active surface is continuous
Rice. 4.4.
1 - at night; 2 - day increases every day. They can persist for several weeks, weakening a little during the day and intensifying again at night.
The radiative inversions are especially intensified with a sharply inhomogeneous terrain. Cooling air flows down into depressions and basins, where weakened turbulent mixing contributes to its further cooling. Radiative inversions associated with the features of the terrain are commonly called orographic. They are dangerous for fruit trees and berry bushes, since the air temperature during such inversions can drop to critical.
Advective inversions are formed during the advection of warm air on a cold underlying surface, which cools the layers of advancing air adjacent to it. These inversions also include snow inversions. They arise during the advection of air having a temperature above 0°C onto a surface covered with snow. The decrease in temperature in the lowest layer in this case is associated with heat consumption for snow melting.
The rays of the Sun, when passing through transparent substances, heat them very weakly. This is due to the fact that direct sunlight practically does not heat up atmospheric air, but strongly heat the earth's surface, capable of transmitting thermal energy adjacent layers of air. As it warms, the air becomes lighter and rises higher. In the upper layers, warm air mixes with cold air, giving it some of the heat energy.
The higher the heated air rises, the more it cools. The air temperature at an altitude of 10 km is constant and is -40-45 °C.
A characteristic feature of the Earth's atmosphere is a decrease in air temperature with height. Sometimes there is an increase in temperature as altitude increases. The name of this phenomenon is temperature inversion(temperature change).
Temperature change
The appearance of inversions may be due to cooling earth's surface and the adjacent air layer in a short period of time. This is also possible when dense cold air moves from mountain slopes to valleys. During the day, the air temperature changes continuously. During the daytime, the earth's surface heats up and heats the lower layer of air. At night, along with the cooling of the earth, the air cools. It is coolest at dawn and warmest in the afternoon.
IN equatorial belt there is no diurnal temperature fluctuation. Night and day temperatures are the same. Diurnal amplitudes on the coasts of the seas, oceans and above their surface are insignificant. But in the desert zone, the difference between night and day temperatures can reach 50-60 ° C.
In the temperate zone maximum amount Solar radiation on Earth falls on the days of the summer solstices. But the hottest month is July in the Northern Hemisphere and January in the Southern. This is explained by the fact that despite the fact that solar radiation is less intense during these months, a huge amount of thermal energy is given off by a very heated earth's surface.
The annual temperature amplitude is determined by the latitude of a certain area. For example, at the equator it is constant and is 22-23 ° C. The highest annual amplitudes are observed in the regions of middle latitudes and deep in the continents.
Absolute and average temperatures are also characteristic of any area. Absolute temperatures are determined through long-term observations at weather stations. The hottest area on Earth is the Libyan Desert (+58°C), and the coldest is Vostok Station in Antarctica (-89.2°C).
Average temperatures are set when calculating the arithmetic mean of several thermometer readings. This is how average daily, average monthly and average annual temperatures are determined.
In order to find out how heat is distributed on Earth, temperatures are plotted on a map and points with the same values are connected. The resulting lines are called isotherms. This method allows you to identify certain patterns in the distribution of temperatures. Yes, most high temperatures are recorded not at the equator, but in tropical and subtropical deserts. A decrease in temperatures from the tropics to the poles in two hemispheres is characteristic. Given that in the Southern Hemisphere, water bodies occupy a larger area than land, the temperature amplitudes between the hottest and coldest months are less pronounced there than in the Northern Hemisphere.
According to the location of the isotherms, seven thermal zones are distinguished: 1 hot, 2 moderate, 2 cold, 2 permafrost areas.
Related content:
In the troposphere, the air temperature decreases with height, as noted, by an average of 0.6 ° C for every 100 m of altitude. However, in the surface layer, the temperature distribution can be different: it can decrease or increase, and remain constant. temperature with height gives the vertical temperature gradient (VGT):
VGT = (/ „ - /B)/(ZB -
where /n - /v - temperature difference at the lower and upper levels, ° С; ZB - ZH- height difference, m. Usually, the VGT is calculated for 100 m of height.
In the surface layer of the atmosphere, the VGT can be 1000 times higher than the average for the troposphere
The value of VGT in the surface layer depends on weather conditions (in clear weather it is greater than in cloudy weather), season (more in summer than in winter) and time of day (more during the day than at night). The wind reduces the VGT, since when the air is mixed, its temperature is equalized at different heights. Above moist soil, WGT sharply decreases in the surface layer, and over bare soil (fallow field) WGT is greater than over dense crops or meadows. This is due to differences in the temperature regime of these surfaces (see Chap. 3).
As a result of a certain combination of these factors, the VGT near the surface in terms of 100 m of height can be more than 100 ° C / 100 m. In such cases, thermal convection occurs.
The change in air temperature with altitude determines the sign of the UGT: if the UGT > 0, then the temperature decreases with distance from the active surface, which usually happens during the day and in summer (Fig. 4.4); if VGT = 0, then the temperature does not change with height; if VGT< 0, то температура увеличивается с высотой и такое распределение температуры называют инверсией.
Depending on the conditions for the formation of inversions in the surface layer of the atmosphere, they are divided into radiative and advective.
1. Radiative inversions occur during radiative cooling of the earth's surface. Such inversions during the warm period of the year are formed at night, and in winter they are also observed during the day. Therefore, radiative inversions are divided into night (summer) and winter ones.
Night inversions are set in clear calm weather after the transition of the radiation balance through 0 for 1.0...1.5 hours before sunset. During the night, they intensify and reach their maximum power before sunrise. After sunrise, the active surface and the air warm up, which destroys the inversion. The height of the inversion layer is most often several tens of meters, but under certain conditions (for example, in closed valleys surrounded by significant elevations) it can reach 200 m or more. This is facilitated by the flow of cooled air from the slopes into the valley. Cloudiness weakens the inversion, and the wind speed of more than 2.5...3.0 m/s destroys it. Under the canopy of dense herbage, crops, as well as forests in summer, inversions are also observed during the day.
Nighttime radiation inversions in spring and autumn, and in some places in summer, can cause a decrease in soil and air surface temperatures to negative values (frosts), which causes damage to many cultivated plants.
Winter inversions occur in clear, calm weather under short day conditions, when the cooling of the active surface continuously increases every day; they can persist for several weeks, weakening a little during the day and increasing again at night.
The radiative inversions are especially intensified with a sharply inhomogeneous terrain. Cooling air flows down into depressions and basins, where weakened turbulent mixing contributes to its further cooling. Radiative inversions associated with the features of the terrain are usually called orographic.
2. Advective inversions are formed during the advection (movement) of warm air onto a cold underlying surface, which cools the layers of advancing air adjacent to it. These inversions also include snow inversions. They arise during the advection of air having a temperature above 0 "C onto a surface covered with snow. A decrease in temperature in the lowest layer in this case is associated with heat costs for melting snow.
INDICATORS OF THE TEMPERATURE REGIME IN THIS AREA AND THE NEEDS OF PLANTS FOR HEAT
When evaluating temperature regime large area or a separate point, temperature characteristics are used for a year or for separate periods (vegetation period, season, month, decade and day). The main of these indicators are as follows.
The average daily temperature is the arithmetic mean of the temperatures measured during all periods of observation. At meteorological stations Russian Federation air temperature is measured eight times a day. Summing up the results of these measurements and dividing the sum by 8, the average daily air temperature is obtained.
The average monthly temperature is the arithmetic average of the average daily temperatures for the entire day of the month.
The mean annual temperature is the arithmetic mean of the mean daily (or mean monthly) temperatures for the entire year.
The average code air temperature gives only a general idea of the amount of heat; it does not characterize the annual temperature variation. So, the average annual temperature in the south of Ireland and in the steppes of Kalmykia, located at the same latitude, is close (9 ° C). But in Ireland, the average January temperature is 5 ... 8 "C, and the meadows are green all winter, and in the steppes of Kalmykia, the average January temperature is -5 ... -8 ° C. In summer, it is cool in Ireland: 14 ° C, and the average July temperature in Kalmykia is 23...26 °C.
Therefore, for more complete characteristics the annual course of temperature in a given place uses data on the average temperature of the coldest (January) and warmest (July) months.
However, all the averaged characteristics do not give an accurate idea of the daily and annual course of temperature, i.e., just about the conditions that are especially important for agricultural production. In addition to the average temperatures are the maximum and minimum temperatures, amplitude. For example, knowing the minimum temperature in winter months, one can judge the conditions for overwintering of winter crops and fruit and berry plantations. Data about maximum temperature show the frequency of thaws in winter and their intensity, and in summer - the number of hot days when grain damage is possible during the filling period, etc.
In extreme temperatures, there are: absolute maximum (minimum) - the highest (lowest) temperature for the entire observation period; average of absolute maximums (minimums) - arithmetic average of absolute extremes; average maximum (minimum) - the arithmetic average of all extreme temperatures, for example, for a month, season, year. At the same time, they can be calculated both for a long-term observation period and for the actual month, year, etc.
The amplitude of the daily and annual temperature variation characterizes the degree of continental climate: the greater the amplitude, the more continental the climate.
A characteristic of the temperature regime in a given area for a certain period is also the sum of average daily temperatures above or below a certain limit. For example, in climate reference books and atlases, the sums of temperatures are given above 0, 5, 10 and 15 ° C, as well as below -5 and -10 "C.
A visual representation of geographical distribution indicators of the temperature regime are given by maps on which isotherms are drawn - lines of equal temperature values \u200b\u200band sums of temperatures (Fig. 4.7). Maps, for example, of the sums of temperatures are used to justify the placement of crops (plantings) of cultivated plants with different requirements for heat.
To clarify the thermal conditions necessary for plants, the sums of day and night temperatures are also used, since the average daily temperature and its sums level out thermal differences in daily course air temperature.
The study of the thermal regime separately for day and night has a deep physiological significance. It is known that all processes occurring in the plant and animal world are subject to natural rhythms determined by external conditions, that is, they are subject to the law of the so-called "biological" clock. For example, according to (1964), for optimal conditions for the growth of tropical plants, the difference between day and night temperatures should be 3 ... 5 ° C, for plants temperate zone-5...7, and for desert plants - 8 °С and more. The study of day and night temperatures acquires special meaning to increase the productivity of agricultural plants, which is determined by the ratio of two processes - assimilation and respiration, occurring in qualitatively different light and dark hours of the day for plants.
The average daytime and nighttime temperatures and their sums indirectly take into account the latitudinal variability in the length of the day and night, as well as changes in the continentality of the climate and the influence of various landforms on the temperature regime.
The sums of average daily air temperatures that are close for a pair of meteorological stations located at approximately the same latitude, but differ significantly in longitude, i.e. located in various conditions climate continentality are given in Table 4.1.
In the more continental eastern regions, the sums of daytime temperatures are 200–500 °C higher, and the sums of night temperatures are 300°C lower than in the western and especially maritime regions, which explains for a long time known fact- accelerating the development of agricultural crops in a sharply continental climate.
The need of plants for heat is expressed by the sums of active and effective temperatures. In agricultural meteorology, active temperature is the average daily air (or soil) temperature above the biological minimum of crop development. The effective temperature is the average daily air (or soil) temperature, reduced by the value of the biological minimum.
Plants develop only if the average daily temperature exceeds their biological minimum, which is, for example, 5 ° C for spring wheat, 10 ° C for corn, and 13 ° C for cotton (15 ° C for southern varieties of cotton). The sums of active and effective temperatures have been established both for individual interphase periods and for the entire growing season of many varieties and hybrids of major crops (Table 11.1).
Through the sums of active and effective temperatures, the need for heat of poikilothermic (cold-blooded) organisms is also expressed both for the ontogenetic period and for centuries. the biological cycle.
When calculating the sums of average daily temperatures that characterize the need of plants and poikilothermic organisms for heat, it is necessary to introduce a correction for ballast temperatures that do not "accelerate growth and development, i.e., take into account the upper temperature level for crops and organisms. For most plants and pests of the temperate zone this will be the average daily temperature exceeding 20 ... 25 "C.
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