The distribution of the average number of days with minimum temperatures on the territory of Russia is associated with circulation processes in the winter period. In winter, when the influx of solar radiation is small or completely absent above the Arctic Circle, they are the main ones. At this time, the European part of Russia and a significant part of Western Siberia are under the influence of western air currents from the Atlantic, and a stable anticyclone is usually located over the Asian part. The winter anticyclone over Eastern Siberia, which is an extremely stable baric formation (the repetition of anticyclones in the south is 26 days a month), contributes to the formation of a cold pole in the east of Russia in the Verkhoyansk-Oymyakon region, from which the temperature rises in all directions. The formation of this pole is favored by a combination of weak winds and low winds, leading to strong radiative cooling, and mountain ranges located on the territory of the Republic of Sakha (Yakutia) both in the meridional and latitudinal directions prevent the penetration of warm air here. As you move east, towards the coasts, horizontal gradients sharply increase. The thickening of isotherms along the coast is explained both by the warming effect of the sea and its closeness from the impact of cold air currents from the land by the ridges of Eastern Siberia.
In the European part of Russia, the direction of isolines of an equal number of days with a temperature greater than or equal to a given value is almost meridional in nature, and in the center of the Asian part of Russia it is zonal, disturbed in areas with a complex surface. A characteristic feature of the system of isolines for the number of days with temperatures below –30°C is their thickening in the direction from west to east. In the European part of Russia, the number of days with temperatures below –30°C varies from 5 days in the south to 30 days in the north, i.e. the difference is 25 days. In the Asian part of Russia, as we move from the Urals to Central Yakutia (toward the cold pole in the region of the Verkhoyansk Range), this difference increases to 100 days. Even greater differences in the number of days with a given temperature are observed on the coasts of the Far East, where, at a distance of slightly more than 600 kilometers, the number of days with temperatures below –30°C varies from 3–10 days on the coasts of the Sea of Okhotsk to 130–160 days per .
Due to the large dependence of the number of days with low temperatures, as well as temperatures in general, on the height and terrain, an extremely complex picture of their distribution is created in the regions of the Altai Mountains, Sayan, Stanovoy, Yablonovoy and. The higher the station is located, the fewer days with low temperatures are observed at it, due to the development of inversions in the mountains during anticyclonic weather. The dependence on relief forms is quite clear. The coldest are deep intermountain valleys and basins. It is in these relief forms that the centers of a large number of days with low temperatures are located in the southeast of Altai (Kosh-Agach - 78 days), in the center of the Sayan Mountains (Kyzyl - 83 days, Erzin - 92 days), in the system of the mountains of the Stanovoy and Yablonovy ridges ( Kalakan - 117 days). In the basins of the Verkhoyansk Ridge, at Verkhoyansk and Oymyakon stations, temperatures below –30°C are observed for half a year. In river valleys, where cold air accumulates and cools off at night, the number of days with temperatures below –30°C is also significantly greater than outside the valleys in the same region.
The smallest number of days with temperatures below -30°C is observed on the coasts of the Far East and, as well as in the European part of Russia south of 50°N. On the coasts of the Chernoy and the islands, no days with temperatures dropping to –30°С or lower have been recorded.
The number of days in a year with temperatures below -30°C has a pronounced annual variation.
The maximum is in January. Only in Yakutia, in the region of the Verkhoyansk Pole of Cold, the number of days in December and January is the same and amounts to almost a whole month.
The mean square deviations of the number of days with a minimum air temperature equal to or below –30°C in Russia varies from 0.07 in the south of the European part of Russia to 80–90 days in the central regions of Yakutia.
Lowering temperatures to -30°C, which is generally unfavorable for humans and the economy, becomes a particularly dangerous phenomenon when such a temperature level is maintained for 10 days or more.
Throughout the European part of Russia, the frequency of this event does not exceed 0.1, and only in the upper reaches of the Pechora does it increase to 0.2. In the Asian part of Russia, a decrease in temperature below -30 ° C for 10 days is noted annually in a vast territory located in the basins of the Lena, Yana and Indigirka rivers, which extends up to. In the western and eastern directions from this area, the frequency of such a severe winter event gradually decreases. Another center of high frequency of temperatures below –30°C for 10 days is located in the areas of the Chui valley of Altai and the Tuva basin of the Sayan.
Advective temperature change- a change in temperature associated with the influx of new air masses into a given place from other parts of the Earth.
adiabatic process- a change in the temperature of the rising or falling air that occurs due to the conversion of the internal energy of the gas into work and work into internal energy without heat exchange with the environment.
Active temperatures Temperature amplitude- the difference between the minimum, absolute or average temperatures for a day, month or year.
Wet adiabatic processis an adiabatic process that occurs in moist saturated air. When the air rises, the temperature decreases by an average of 0.6ºC per 100 m., when lowering, the temperature rises by 1ºC per 100 m. the air becomes unsaturated as it descends.
Degree(°, deg) - division part of the scale, temperature unit. The degree value depends on the selected scale. The basic unit of temperature (according to the international system of units SI) is 1° Kelvin (1°K) on the thermodynamic temperature scale, in which the temperature of the triple point of water is set to 273.16°K. 1° Celsius (1°C) is equal to 1/100 of the scale between the fixed points of melting ice (0°C) and boiling water (100°C) at normal pressure (760 mmHg).
frost- a decrease in air temperature below 0ºС at night with a positive temperature during the day.
Isotherms- lines of equal temperatures on meteorological maps.
Temperature inversion- an increase in air temperature with height.
Convection- the rise of heated from the earth's surface (less dense) air masses. The speed of vertical air currents can reach 30 m/s.
Thaw- the onset in the middle of winter in temperate and high latitudes of warm weather with positive temperatures against the background of established negative temperatures.
Inversion layerA layer of air in which the temperature increases with height.
Layer of constant diurnal temperature- a layer of soil (water), in which daily temperature fluctuations are not observed.
Average air temperature- the arithmetic mean of the sum of temperatures per day, decade, month, year.
Dry adiabatic process- an adiabatic process that occurs in an ideal gas, dry or unsaturated air. During an adiabatic rise, the air temperature decreases by 1ºC for every 100 m., when the air descends, the temperature rises by 1ºC per 100 m.
temperature scaleis a system of comparable numerical values of temperature. Each temperature scale contains two or more fiducial points denoting the temperature of any reproducible process. Common reference points are the melting points of ice and the boiling point of water. In practical meteorology, they use centigrade scales(°C) and Fahrenheit(°F, °F - England, USA). On the first of them, the specified reference points are marked 0° and +100°, on the second, +32° and +242°. The transition from one scale to another is done according to the formula: t ° C \u003d 5/9 (t ° F - 32); t°F = 9/5 (t°C + 32). V approximate absolute scale these reference points are designated 273°K and 373°K.
thermal belt- this is the belt of the Earth, limited by certain isotherms. There are 7 zones in total: 1 hot, 2 moderate, 2 cold and 2 frost zones.
Thermals- powerful upward movement of air during thermal convection.
Thermal convection- random movement of air particles caused by its heating from an unevenly heated underlying surface. It can be disordered and ordered.
thermal equator- a line connecting the highest average annual or average monthly temperatures on different meridiansfrost
For "frost, decrease in air temperature below 0 ° C in the evening and at night with a positive temperature during the day. The emergence of frost is caused either by the intrusion of cold air masses that have come from other regions (more often from the Arctic) - advective frost, or by nighttime radiative cooling of the surface of the soil and vegetation cover - radiation frost. However, in most cases, frost plays a role in the emergence of the preliminary advection of a mass of cold air into a given area, and the subsequent night radiation, which cools the soil, and from it the air to negative temperatures. Usually, in the central zone of the USSR, z. are in the spring (until the middle of June) and in the fall (starting from the second half of September).
Z. can be the cause of a significant reduction in the yield of field, vegetable and fruit crops. The destructive effect of Z. on the page - x. culture is explained by the direct effect of low temperature on a living cell, during which water is frozen out of the cell sap, ice crystals are formed in the intercellular spaces, and protoplasm is dehydrated. The most resistant plants that withstand short-term frosts from -7 to -10°C are early spring grains and legumes of early sowing; medium-resistant, enduring from -3 to -4 ° C, - soybean, mogar, rope, etc .; low-resistant, able to tolerate from -2 to -3 ° C - corn, millet, sorghum, potatoes, shag, etc.; unstable plants, the seedlings of which are damaged from -0.5 to -1.5 ° C, - beans, rice, cotton, melons, sesame, peanuts, buckwheat, etc. Generative organs are especially sensitive to Z..
In the fight against Z., the introduction of early-ripening varieties of agricultural crops is of great importance. crops in areas with a short frost-free period, plant breeding for frost resistance, the use of potash fertilizers, as well as timely agricultural production. work, the right choice of sowing site, taking into account the microclimate, etc. The most well-known and widespread method of controlling frost is smoke, which is widely used to protect flowering fruit crops and the seedlings of heat-loving vegetable crops in the central and southern regions of the USSR. In the subtropics of the USSR, open heating is used on lemon plantations (the air among the plants is heated by burning oil, coal, etc. combustible substances in special heaters); they also practice covering lemons and oranges with three-layer gauze. Heating plantations with electric heaters, hot water batteries or steam is effective, but expensive and applicable only to obtain valuable products.
Lit.: Berlyand M. E., Krasikov P. N., Frost prediction and control, 2nd ed., L., 1960; Gol'tsberg I. A., Agro-climatic characteristics of frosts in the USSR and methods of dealing with them. L., 1961.
I. A. Gol'tsberg.
Our planet has a spherical shape, so the sun's rays fall on the earth's surface at different angles and heat it unevenly. At the equator, where the sun's rays fall vertically, the Earth's surface heats up more. The closer to the poles, the smaller the angle of incidence of the sun's rays and the weaker the surface heats up.
In the polar regions, the rays seem to glide over the planet and hardly heat it up. In addition, passing in a long way, the sun's rays are strongly scattered and bring less heat to the Earth. The surface layer of air is heated from the underlying surface, therefore, the air temperature decreases from the equator to the poles.
It is known that the earth's axis is inclined to the plane of the orbit along which the Earth revolves around the Sun, so the Northern and Southern hemispheres heat up unevenly depending on the seasons, which also affects.
At any point on Earth, the air temperature changes during the day and throughout the year. It depends on how high the Sun is above the horizon and the length of the day. During the day, the highest temperature is observed at 14-15 hours, and the lowest - shortly after sunrise.
The change in temperature from the equator to the poles depends not only on the geographical latitude of the place, but also on the planetary transfer of heat from low latitudes to high latitudes, on the distribution of continents and oceans on the surface of the planet, which are differently heated by the Sun and give off heat differently, as well as on the position mountain ranges and ocean currents. For example, the Northern Hemisphere is warmer than the Southern Hemisphere, because in the southern polar region there is a large continent of Antarctica, covered with an ice shell.
On maps, the air temperature above the earth's surface is shown using isotherms - lines connecting points with the same temperature. Isotherms are close to parallel only where they cross oceans, and curve strongly over continents.
On the basis of isotherm maps, thermal zones are distinguished on the planet. The hot belt is located in the equatorial latitudes between the average annual isotherms of +20 °С. Temperate zones are located to the north and south of the hot zone and are limited by isotherms of + 10 °C. Two cold belts lie between the isotherms + 10 °С and 0 °С, and there are frost belts at the North and South Poles.
With altitude, the air temperature decreases by an average of 6 ° C when rising by 1 km.
In autumn and spring, frosts often occur - a decrease in air temperature at night below 0 ° C, while average daily temperatures are above zero. Frosts most often occur on clear, quiet nights, when rather cold ones enter the given territory, for example, from the Arctic. During frosts, the air cools significantly near the earth's surface, it turns out to be warm above the cold layer of air, and a temperature inversion occurs - an increase in temperature with height. It is often observed in the polar regions, where the earth's surface is strongly cooled at night.
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