Atmospheric circulation. Air masses and their circulation What is the movement of air masses

Air masses- these are the moving parts of the troposphere, differing from each other in their properties - temperature, transparency. These properties of air masses depend on the territory over which they are formed under the condition of a long stay. Depending on the formation, there are 4 main types of air masses: (), tropical and. Each of these four types is formed over an area of ​​land and sea. Since land and sea heat up to different degrees, subtypes can form in each of these types - continental and marine air masses.

Arctic (Antarctic) air forms over the icy surface of polar latitudes; characterized by low temperatures, low moisture content, while the Arctic sea air is more humid than continental air. Invading low latitudes, Arctic air significantly lowers temperatures. The flat terrain facilitates its penetration far into the interior of the continent. A similar phenomenon can be observed. As it moves south, the Arctic air warms up and contributes to the formation of dry winds, which cause frequent winds in the area.

Moderate air masses form in temperate latitudes. Continental temperate air masses are greatly cooled in winter. They have a low moisture content. With the invasion of continental air masses, clear frosty weather sets in. In summer, continental air is dry and very hot. Marine air masses of temperate latitudes are humid, moderate; In winter they bring thaws, in summer they bring cloudy weather and colder temperatures.

Tropical air masses form throughout the year in the tropics. Typically, the marine variety is characterized by high humidity and temperature, while the continental variety is characterized by dustiness, dryness and even higher temperatures.

Equatorial air masses are formed in the equatorial zone. around its axis contributes to the movement of air masses either to the Northern Hemisphere or to the Southern Hemisphere. These air masses are characterized by high temperature and high humidity, and there is no clear division for them into marine air masses and continental ones.

The resulting air masses inevitably begin to move. The reason for this is the uneven heating of the earth's surface and, as a consequence, the difference. If there were no movement of air masses, then at the equator the average annual temperature would be 13° higher, and at latitudes 70° - 23° lower than at present.

Invading areas with different surface thermal properties, air masses are gradually transformed. For example, temperate sea air, entering land and moving inland, gradually heats up and dries out, turning into continental air. The transformation of air masses is especially characteristic of temperate latitudes, into which warm and dry air from the latitudes and cold and dry air from the subpolar ones invade from time to time.

The movement of air masses should lead, first of all, to smoothing baric and temperature gradients. However, on our rotating planet with different heat capacity properties of the earth’s surface, different heat reserves of land, seas and oceans, the presence of warm and cold ocean currents, polar and continental ice, the processes are very complex and often the contrasts in the heat content of various air masses are not only not smoothed out, but, on the contrary, , increase.[...]

The movement of air masses over the Earth's surface is determined by many reasons, including the rotation of the planet, uneven heating of its surface by the Sun, the formation of zones of low (cyclones) and high (anticyclones) pressure, flat or mountainous terrain, and much more. In addition, at different altitudes the speed, stability and direction of air flows are very different. Therefore, the transport of pollutants entering different layers of the atmosphere occurs at different speeds and sometimes in other directions than in the ground layer. With very strong emissions associated with high energies, pollution entering high, up to 10-20 km, layers of the atmosphere can move thousands of kilometers within a few days or even hours. Thus, volcanic ash ejected by the explosion of the Krakatoa volcano in Indonesia in 1883 was observed in the form of peculiar clouds over Europe. Radioactive fallout of varying intensity after testing particularly powerful hydrogen bombs fell on almost the entire surface of the Earth.[...]

Movement of air masses - wind, resulting from differences in temperatures and pressures in different regions of the planet, affects not only the physical and chemical properties of the air itself, but also the intensity of heat exchange, changes in humidity, pressure, chemical composition of the air, reducing or increasing the amount pollution.[...]

The movement of air masses can be in the form of their passive movement of a convective nature or in the form of wind - due to the cyclonic activity of the Earth's atmosphere. In the first case, the dispersal of spores, pollen, seeds, microorganisms and small animals is ensured, which have special devices for this - anemochores: very small sizes, parachute-like appendages, etc. (Fig. 2.8). This entire mass of organisms is called aeroplankton. In the second case, the wind also transports aeroplankton, but over much longer distances, and can also transport pollutants to new zones, etc. [...]

Movement of air masses (wind). As is known, the reason for the formation of wind flows and the movement of air masses is the uneven heating of different parts of the earth's surface associated with pressure changes. The wind flow is directed towards lower pressure, but the rotation of the Earth also affects the circulation of air masses on a global scale. In the surface layer of air, the movement of air masses influences all meteorological factors of the environment, i.e. climate, including regimes of temperature, humidity, evaporation from the surface of land and sea, as well as plant transpiration.[...]

ABNORMAL MOVEMENT OF THE CYCLONE. The movement of a cyclone in a direction sharply diverging from the usual one, i.e. from the eastern half of the horizon to the western half or along the meridian. A.P.C. is associated with the anomalous direction of the leading flow, which in turn is caused by the unusual distribution of warm and cold air masses in the troposphere.[...]

AIR MASS TRANSFORMATION. 1. A gradual change in the properties of the air mass as it moves due to changes in the conditions of the underlying surface (relative transformation).[...]

The third reason for the movement of air masses is dynamic, which contributes to the formation of areas of high pressure. Due to the fact that the most heat comes to the equatorial zone, air masses rise up to 18 km here. Therefore, intense condensation and precipitation in the form of tropical showers are observed. In the so-called “horse” latitudes (about 30° N and 30° S), cold dry air masses, sinking and adiabatically heating, intensively absorb moisture. Therefore, the main deserts of the planet naturally form in these latitudes. They mainly formed in the western parts of the continents. The westerly winds coming from the ocean do not contain enough moisture to transfer to the descending dry air. Therefore, there is very little rainfall here.[...]

The formation and movement of air masses, the location and trajectories of cyclones and anticyclones are of great importance for making weather forecasts. A synoptic map gives a visual representation of the weather condition at a given moment over a vast territory.[...]

WEATHER CHANGE. The movement of certain weather conditions together with their “carriers” - air masses, fronts, cyclones and anticyclones. [...]

In a narrow boundary strip separating air masses, frontal zones (fronts) arise, characterized by an unstable state of meteorological elements: temperature, pressure, humidity, wind direction and speed. Here, the most important principle of environmental contrast in physical geography is manifested with exceptional clarity, expressed in a sharp activation of the exchange of matter and energy in the zone of contact (contact) of natural complexes and their components that differ in their properties (F.N. Milkov, 1968). The active exchange of matter and energy between air masses in the frontal zones is manifested in the fact that it is here that the origin, movement with a simultaneous increase in power and, finally, the extinction of cyclones occur.[...]

Solar energy causes planetary movements of air masses as a result of their uneven heating. Grandiose processes of atmospheric circulation arise, which are rhythmic in nature.[...]

If in a free atmosphere during turbulent movements of air masses this phenomenon does not play a noticeable role, then in still or low-moving indoor air this difference should be taken into account. In close proximity to the surface of various bodies, we will have a layer with some excess of negative air ions, while the surrounding air will be enriched with positive air ions.[...]

Non-periodic weather changes are caused by the movement of air masses from one geographical area to another in the general atmospheric circulation system.[...]

Due to the fact that at high altitudes the speed of movement of air masses reaches 100 m/sec, ions moving in a magnetic field can be displaced, although these displacements are insignificant compared to transport in the flow. What is important for us is the fact that in the polar zones, where the Earth's magnetic field lines are closed on its surface, the distortions of the ionosphere are very significant. The number of ions, including ionized oxygen, in the upper layers of the atmosphere of the polar zones is reduced. But the main reason for the low ozone content in the polar region is the low intensity of solar radiation, which falls even during the polar day at small angles to the horizon, and is completely absent during the polar night. In itself, the shielding role of the ozone layer in the polar regions is not so important precisely because of the low position of the Sun above the horizon, which eliminates the high intensity of UV irradiation of the surface. However, the area of ​​polar “holes” in the ozone layer is a reliable indicator of changes in the total ozone content in the atmosphere.[...]

Translational horizontal movements of water masses associated with the movement of significant volumes of water over long distances are called currents. Currents arise under the influence of various factors, such as wind (i.e., friction and pressure of moving air masses on the water surface), changes in the distribution of atmospheric pressure, uneven distribution of the density of sea water (i.e., horizontal pressure gradient of waters of different densities at the same depths), tidal forces of the Moon and the Sun. The nature of the movement of water masses is also significantly influenced by secondary forces, which do not themselves cause it, but appear only in the presence of movement. These forces include the force arising due to the rotation of the Earth - the Coriolis force, centrifugal forces, friction of water against the bottom and shores of continents, internal friction. Sea currents are greatly influenced by the distribution of land and sea, bottom topography and coastal contours. Currents are classified mainly by origin. Depending on the forces that excite them, currents are combined into four groups: 1) frictional (wind and drift), 2) gradient-gravitational, 3) tidal, 4) inertial.[...]

Wind turbines and sailing ships are propelled by the movement of masses of air due to the heating of it by the sun and the creation of air currents or winds. 1.[ ...]

TRAFFIC CONTROL. Formulation of the fact that the movement of air masses and tropospheric disturbances mainly occurs in the direction of isobars (isohypses) and, consequently, air currents of the upper troposphere and lower stratosphere.[...]

This, in turn, may lead to disruption of the movement of air masses near industrial areas located near such a park and increased air pollution.[...]

Most weather phenomena depend on whether air masses are stable or unstable. When the air is stable, vertical movements in it are difficult; when the air is unstable, on the contrary, they develop easily. The criterion for stability is the observed temperature gradient.[...]

Hydrodynamic, closed type with adjustable air cushion pressure, with pulsation damper. Structurally, it consists of a body with a lower lip, a collector with a tilting mechanism, a turbulator, an upper lip with a mechanism for vertical and horizontal movement, mechanisms for precise adjustment of the profile of the outlet slot with the ability to automatically control the transverse profile of the paper web. The surfaces of the box parts in contact with the mass are thoroughly polished and electropolished.[...]

Potential temperature, in contrast to molecular temperature T, remains constant during dry adiabatic movements of the same air particle. If during the movement of the air mass its potential temperature changes, then an influx or outflow of heat is observed. Dry adiabatic is a line of equal value of potential temperature.[...]

The most typical case of dispersion is the movement of a gas jet in a moving medium, i.e., during the horizontal movement of atmospheric air masses.[...]

The main reason for short-period OS oscillations, according to the concept put forward in 1964 by the author of the work, is the horizontal movement of the ST axis, directly related to the movement of long waves in the atmosphere. Moreover, the direction of the wind in the stratosphere above the observation site does not play a significant role. In other words, short-period oscillations of the OS are caused by changes in air masses in the stratosphere above the observation site, since these masses separate the ST.[...]

Due to the large area of ​​their surface, the state of the free surface of reservoirs is strongly influenced by wind. The kinetic energy of the air flow is transferred to the water masses through friction forces at the interface of the two media. One part of the transferred energy is spent on the formation of waves, and the other goes to create a drift current, i.e. progressive movement of surface layers of water in the direction of the wind. In reservoirs of limited size, the movement of water masses by a drift current leads to a skew of the free surface. Near the windward coast the water level decreases - a wind surge occurs; near the leeward coast the level rises - a wind surge occurs. At the Tsimlyansk and Rybinsk reservoirs, level differences of 1 m or more were recorded at the leeward and windward shores. With prolonged wind, the distortion becomes stable. Masses of water that are supplied to the lee shore by the drift current are removed in the opposite direction by the bottom gradient current.[...]

The results obtained are based on solving the problem for stationary conditions. However, the terrain scales under consideration are relatively small and the time of movement of the air mass ¿ = l:/i is small, which allows us to limit ourselves to parametric consideration of the characteristics of the oncoming air flow.[...]

But the icy Arctic causes complications in agriculture not only due to cold and long winters. Cold, and therefore dehydrated, arctic air masses do not warm up during the spring-summer movement. The higher the air temperature, the more pain! moisture is needed to saturate it. I. P. Gerasimov and K. K. Mkov noted that “at present, a simple increase in ice cover in the Arctic basin causes. . . zas; in Ukraine and the Volga region" 2.[...]

In 1889, a giant cloud of locusts flew from the coast of North Africa across the Red Sea to Arabia. The movement of insects lasted the whole day, and their mass amounted to 44 million tons. V.I. Vernadsky regarded this fact as evidence of the enormous power of living matter, an expression of the pressure of life striving to capture the entire Earth. At the same time, he saw in this a biogeochemical process - the migration of elements included in the locust biomass, a completely special migration - through the air, over long distances, not consistent with the usual regime of movement of air masses in the atmosphere.[...]

Thus, the main factor determining the speed of katabatic winds is the temperature difference between the ice cover and the atmosphere 0 and the angle of inclination of the ice surface. The movement of a cooled air mass down the slope of the Antarctic ice dome is enhanced by the effects of the fall of the air mass from the height of the ice dome and the influence of pressure gradients in the Antarctic anticyclone. Horizontal baric gradients, being an element of the formation of katabatic winds in Antarctica, contribute to increased air outflow to the periphery of the continent, primarily due to its supercooling at the surface of the ice sheet and the slopes of the ice dome towards the sea. [...]

The analysis of synoptic maps is as follows. Based on the information plotted on the map, the actual state of the atmosphere at the time of observation is established: the distribution and nature of air masses and fronts, the location and properties of atmospheric disturbances, the location and nature of cloudiness and precipitation, temperature distribution, etc. for given atmospheric circulation conditions. By compiling maps for different periods, you can use them to monitor changes in the state of the atmosphere, in particular the movement and evolution of atmospheric disturbances, the movement, transformation and interaction of air masses, etc. The representation of atmospheric conditions on synoptic maps provides a convenient opportunity for information about the state of the weather.[. ..]

Atmospheric macroscale processes studied using synoptic maps and causing weather patterns over large geographic areas. This is the emergence, movement and change in the properties of air masses and atmospheric fronts; the emergence, development and movement of atmospheric disturbances - cyclones and anticyclones, the evolution of condensation systems, intramass and frontal, in connection with the above processes, etc.[...]

Until aerial chemical treatment is completely excluded, it is necessary to make improvements in its use by carefully selecting objects, reducing the likelihood of “drifts” - movements of sawing air masses, controlled dosage, etc. For primary care in clearings by using herbicides, it is advisable to use typological diagnostics to a greater extent fellings Chemistry is a powerful means of caring for forests. But it is important that chemical care does not turn into poisoning of the forest, its inhabitants and visitors.[...]

In the nature around us, water is in constant motion - and this is just one of many natural cycles of substances in nature. When we say “movement,” we mean not only the movement of water as a physical body (flow), not only its movement in space, but, above all, the transition of water from one physical state to another. In Figure 1 you can see how the water cycle occurs. On the surface of lakes, rivers and seas, water under the influence of the energy of sunlight turns into water vapor - this process is called evaporation. In the same way, water evaporates from the surface of snow and ice, from the leaves of plants and from the bodies of animals and humans. Water vapor with warmer air currents rises to the upper layers of the atmosphere, where it gradually cools and turns back into a liquid or turns into a solid state - this process is called condensation. At the same time, water moves with the movement of air masses in the atmosphere (winds). From the resulting water droplets and ice crystals, clouds are formed, from which rain or snow eventually falls to the ground. The water returning to the earth in the form of precipitation flows down the slopes and collects in streams and rivers that flow into lakes, seas and oceans. Some of the water seeps through the soil and rocks and reaches underground and groundwater, which also, as a rule, flow into rivers and other bodies of water. Thus, the circle closes and can be repeated in nature endlessly.[...]

SYNOPTIC METEOROLOGY. A meteorological discipline that took shape in the second half of the 19th century. and especially in the 20th century; the study of atmospheric macroscale processes and weather prediction based on their study. Such processes are the emergence, evolution and movement of cyclones and anticyclones, which are closely related to the emergence, movement and evolution of air masses and fronts between them. The study of these synoptic processes is carried out using a systematic analysis of synoptic maps, vertical sections of the atmosphere, aerological diagrams and other auxiliary means. The transition from synoptic analysis of circulation conditions over large areas of the earth's surface to their forecast and to the forecast of associated weather conditions still largely comes down to extrapolation and qualitative conclusions from the provisions of dynamic meteorology. However, in the last 25 years, numerical (hydrodynamic) forecasting of meteorological fields has been increasingly used by numerically solving the equations of atmospheric thermodynamics on electronic computers. See also weather service, weather forecast and a number of other terms. Common synonym: weather forecaster.[...]

The case of jet propagation that we have analyzed is not typical, since there are very few windless periods in almost any area. Therefore, the most typical case of scattering is the movement of a gas jet in a moving medium, i.e., in the presence of horizontal movement of atmospheric air masses. [...]

It is obvious that simply air temperature T is not a conservative characteristic of the heat content of air. Thus, with a constant heat content of an individual volume of air (turbulent mole), its temperature can vary depending on pressure (1.1). Atmospheric pressure, as we know, decreases with altitude. As a result, vertical movement of air leads to changes in its specific volume. In this case, the work of expansion is realized, which leads to changes in the temperature of air particles even in the case when the processes are isentropic (adiabatic), i.e. there is no heat exchange between an individual mass element and the space surrounding it. Changes in the temperature of the air moving vertically will correspond to dry-diabatic or moist-diabatic gradients, depending on the nature of the thermodynamic process.

Movements of air masses

The air is in constant motion, especially due to the activity of cyclones and anticyclones.

A warm air mass that moves from warm to colder areas causes unexpected warming when it arrives. At the same time, from contact with the colder earth's surface, the moving air mass from below is cooled and the layers of air adjacent to the ground may turn out to be even colder than the upper layers. Cooling of the warm air mass coming from below causes condensation of water vapor in the lowest layers of air, resulting in the formation of clouds and precipitation. These clouds are located low, often descend to the ground and cause fog. The lower layers of the warm air mass are quite warm and there are no ice crystals. Therefore, they cannot give heavy rainfall; only occasional light, drizzling rain falls. Clouds of warm air mass cover the entire sky with an even layer (then called stratus) or a slightly wavy layer (then called stratocumulus).

A cold air mass moves from cold areas to warmer ones and brings cooling. Moving to a warmer earth's surface, it is continuously heated from below. When heated, not only does condensation not occur, but existing clouds and fogs must evaporate, however, the sky does not become cloudless, clouds simply form for completely different reasons. When heated, all bodies heat up and their density decreases, so when the lowest layer of air heats up and expands, it becomes lighter and, as it were, floats up in the form of separate bubbles or jets and heavier cold air descends in its place. Air, like any gas, heats up when compressed and cools when expanded. Atmospheric pressure decreases with height, so the air, rising, expands and cools by 1 degree for every 100 m of rise, and as a result, at a certain altitude, condensation and the formation of clouds begin in it. The descending jets of air from compression heat up and not only nothing condenses in them , but even the remnants of clouds that fall into them evaporate. Therefore, clouds of cold air masses look like clouds piling up in height with gaps between them. Such clouds are called cumulus or cumulonimbus. They never descend to the ground and do not turn into fogs, and, as a rule, do not cover the entire visible sky. In such clouds, rising air currents carry water droplets with them into those layers where there are always ice crystals, while the cloud loses its characteristic “cauliflower” shape and the cloud turns into a cumulonimbus. From this moment on, precipitation falls from the cloud, although heavy, but short-lived due to the small size of the clouds. Therefore, the weather of cold air masses is very unstable.

Atmospheric front

The boundary of contact between different air masses is called the atmospheric front. On synoptic maps, this boundary is a line that meteorologists call the “front line.” The boundary between warm and cold air masses is an almost horizontal surface that drops imperceptibly towards the front line. Cold air is under this surface, and warm air is on top. Since air masses are constantly in motion, the boundary between them is constantly shifting. An interesting feature: a front line always passes through the center of an area of ​​low pressure, but a front never passes through the centers of areas of high pressure.

A warm front occurs when a warm air mass moves forward and a cold air mass retreats. Warm air, being lighter, creeps over cold air. Because rising air cools it, clouds form above the surface of the front. Warm air rises slowly enough, so the cloudiness of a warm front is a smooth blanket of cirrostratus and altostratus clouds, which is several hundred meters wide and sometimes thousands of kilometers long. The further ahead of the front line the clouds are, the higher and thinner they are.

A cold front moves towards warm air. At the same time, cold air creeps under the warm air. Due to friction with the earth's surface, the lower part of the cold front lags behind the upper part, so the surface of the front bulges forward.

Atmospheric vortices

The development and movement of cyclones and anticyclones leads to the transfer of air masses over significant distances and corresponding non-periodic weather changes associated with changes in wind directions and speeds, with an increase or decrease in cloudiness and precipitation. In cyclones and anticyclones, air moves in the direction of decreasing atmospheric pressure, deflecting under the influence of various forces: centrifugal, Coriolis, friction, etc. As a result, in cyclones the wind is directed towards its center with rotation counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere, in anticyclones, on the contrary, from the center with opposite rotation.

Cyclone- an atmospheric vortex of huge diameter (from hundreds to 2-3 thousand kilometers) with low atmospheric pressure in the center. There are extratropical and tropical cyclones.

Tropical cyclones (typhoons) have special properties and occur much less frequently. They are formed in tropical latitudes (from 5° to 30° of each hemisphere) and have smaller sizes (hundreds, rarely more than a thousand kilometers), but larger pressure gradients and wind speeds, reaching hurricane speeds. Such cyclones are characterized by the “eye of the storm” - a central area with a diameter of 20-30 km with relatively clear and calm weather. Around there are powerful continuous accumulations of cumulonimbus clouds with heavy rain. Tropical cyclones can become extratropical during their development.

Extratropical cyclones form mainly on atmospheric fronts, most often located in subpolar regions, and contribute to the most significant weather changes. Cyclones are characterized by cloudy and rainy weather and are associated with most of the precipitation in the temperate zone. The center of an extratropical cyclone has the most intense precipitation and the densest cloud cover.

Anticyclone- area of ​​high atmospheric pressure. Usually the weather of an anticyclone is clear or partly cloudy. Small-scale eddies (tornadoes, blood clots, tornadoes) are also important for the weather.

weather - a set of values ​​of meteorological elements and atmospheric phenomena observed at a certain point in time at a particular point in space. Weather refers to the current state of the atmosphere, as opposed to Climate, which refers to the average state of the atmosphere over a long period of time. If there is no clarification, then the term “Weather” refers to the weather on Earth. Weather phenomena occur in the troposphere (lower atmosphere) and in the hydrosphere. Weather can be described by air pressure, temperature and humidity, wind strength and direction, cloud cover, precipitation, visibility range, atmospheric phenomena (fog, snowstorms, thunderstorms) and other meteorological elements.

Climate(Ancient Greek κλίμα (gen. κλίματος) - slope) - long-term weather regime characteristic of a given area due to its geographical location.

Climate is a statistical ensemble of states through which the system passes: hydrosphere → lithosphere → atmosphere over several decades. Climate is usually understood as the average weather value over a long period of time (of the order of several decades), that is, climate is the average weather. Thus, weather is the instantaneous state of some characteristics (temperature, humidity, atmospheric pressure). Deviation of weather from the climate norm cannot be considered as climate change; for example, a very cold winter does not indicate a cooling of the climate. To detect climate change, a significant trend in atmospheric characteristics over a long period of time of the order of ten years is needed. The main global geophysical cyclic processes that shape climate conditions on Earth are heat circulation, moisture circulation and general atmospheric circulation.

Distribution of precipitation on Earth. Atmospheric precipitation on the earth's surface is distributed very unevenly. Some areas suffer from excess moisture, others from lack of it. Areas located along the Northern and Southern Tropics, where temperatures are high and the need for precipitation is especially great, receive very little precipitation. Vast areas of the globe, which have a lot of heat, are not used in agriculture due to lack of moisture.

How can we explain the uneven distribution of precipitation on the earth's surface? You probably already guessed that the main reason is the placement of belts of low and high atmospheric pressure. Thus, near the equator in a low-pressure zone, constantly heated air contains a lot of moisture; As it rises, it cools and becomes saturated. Therefore, in the equator region there are many clouds and heavy rainfall. A lot of precipitation also falls in other areas of the earth's surface (see Fig. 18), where there is low pressure.

Climate-forming factors In high pressure zones, downward air currents predominate. Cold air, as it descends, contains little moisture. When lowered, it contracts and heats up, making it drier. Therefore, in areas of high pressure over the tropics and at the poles, little precipitation falls.

CLIMATIC ZONING

The division of the earth's surface according to the generality of climatic conditions into large zones, which are parts of the surface of the globe, having a more or less latitudinal extent and identified according to certain climatic indicators. The latitudinal region does not necessarily have to cover the entire hemisphere in latitude. Climatic regions are distinguished in climatic zones. There are vertical zones identified in the mountains and lying one above the other. Each of these zones has a specific climate. In different latitudinal zones, the vertical climate zones of the same name will have different climate characteristics.

Ecological and geological role of atmospheric processes

A decrease in the transparency of the atmosphere due to the appearance of aerosol particles and solid dust in it affects the distribution of solar radiation, increasing the albedo or reflectivity. Various chemical reactions that cause the decomposition of ozone and the generation of “pearl” clouds consisting of water vapor lead to the same result. Global changes in reflectivity, as well as changes in atmospheric gases, mainly greenhouse gases, are responsible for climate change.

Uneven heating, which causes differences in atmospheric pressure over different parts of the earth's surface, leads to atmospheric circulation, which is the hallmark of the troposphere. When a difference in pressure occurs, air rushes from areas of high pressure to areas of low pressure. These movements of air masses, together with humidity and temperature, determine the main ecological and geological features of atmospheric processes.

Depending on the speed, the wind performs various geological work on the earth's surface. At a speed of 10 m/s, it shakes thick tree branches, lifting and transporting dust and fine sand; breaks tree branches at a speed of 20 m/s, carries sand and gravel; at a speed of 30 m/s (storm) tears off the roofs of houses, uproots trees, breaks poles, moves pebbles and carries small rubble, and a hurricane wind at a speed of 40 m/s destroys houses, breaks and demolishes power line poles, uproots large trees.

Squalls and tornadoes (tornadoes) - atmospheric vortices that arise in the warm season on powerful atmospheric fronts, with speeds of up to 100 m/s, have a great negative environmental impact with catastrophic consequences. Squalls are horizontal whirlwinds with hurricane wind speeds (up to 60-80 m/s). They are often accompanied by heavy downpours and thunderstorms lasting from several minutes to half an hour. Squalls cover areas up to 50 km wide and travel a distance of 200-250 km. A squall storm in Moscow and the Moscow region in 1998 damaged the roofs of many houses and toppled trees.

Tornadoes, called tornadoes in North America, are powerful funnel-shaped atmospheric vortices, often associated with thunderclouds. These are columns of air tapering in the middle with a diameter of several tens to hundreds of meters. A tornado has the appearance of a funnel, very similar to the trunk of an elephant, descending from the clouds or rising from the surface of the earth. Possessing strong rarefaction and a high rotation speed, a tornado travels up to several hundred kilometers, drawing in dust, water from reservoirs and various objects. Powerful tornadoes are accompanied by thunderstorms, rain and have great destructive power.

Tornadoes rarely occur in subpolar or equatorial regions, where it is constantly cold or hot. There are few tornadoes in the open ocean. Tornadoes occur in Europe, Japan, Australia, the USA, and in Russia they are especially frequent in the Central Black Earth region, in the Moscow, Yaroslavl, Nizhny Novgorod and Ivanovo regions.

Tornadoes lift and move cars, houses, carriages, and bridges. Particularly destructive tornadoes are observed in the United States. Every year there are from 450 to 1500 tornadoes with an average death toll of about 100 people. Tornadoes are fast-acting catastrophic atmospheric processes. They are formed in just 20-30 minutes, and their lifetime is 30 minutes. Therefore, it is almost impossible to predict the time and place of tornadoes.

Other destructive but long-lasting atmospheric vortices are cyclones. They are formed due to a pressure difference, which under certain conditions contributes to the emergence of a circular movement of air flows. Atmospheric vortices originate around powerful upward flows of moist warm air and rotate at high speed clockwise in the southern hemisphere and counterclockwise in the northern. Cyclones, unlike tornadoes, originate over oceans and produce their destructive effects over continents. The main destructive factors are strong winds, intense precipitation in the form of snowfall, downpours, hail and surge floods. Winds with speeds of 19 - 30 m/s form a storm, 30 - 35 m/s - a storm, and more than 35 m/s - a hurricane.

Tropical cyclones - hurricanes and typhoons - have an average width of several hundred kilometers. The wind speed inside the cyclone reaches hurricane force. Tropical cyclones last from several days to several weeks, moving at speeds from 50 to 200 km/h. Mid-latitude cyclones have a larger diameter. Their transverse dimensions range from a thousand to several thousand kilometers, and the wind speed is stormy. They move in the northern hemisphere from the west and are accompanied by hail and snowfall, which are catastrophic in nature. In terms of the number of victims and damage caused, cyclones and associated hurricanes and typhoons are the largest natural atmospheric phenomena after floods. In densely populated areas of Asia, the death toll from hurricanes is in the thousands. In 1991, during a hurricane in Bangladesh, which caused the formation of sea waves 6 m high, 125 thousand people died. Typhoons cause great damage to the United States. At the same time, tens and hundreds of people die. In Western Europe, hurricanes cause less damage.

Thunderstorms are considered a catastrophic atmospheric phenomenon. They occur when warm, moist air rises very quickly. On the border of the tropical and subtropical zones, thunderstorms occur 90-100 days a year, in the temperate zone 10-30 days. In our country, the largest number of thunderstorms occur in the North Caucasus.

Thunderstorms usually last less than an hour. Particularly dangerous are intense downpours, hail, lightning strikes, gusts of wind, and vertical air currents. The hail hazard is determined by the size of the hailstones. In the North Caucasus, the mass of hailstones once reached 0.5 kg, and in India, hailstones weighing 7 kg were recorded. The most urban-dangerous areas in our country are located in the North Caucasus. In July 1992, hail damaged 18 aircraft at the Mineralnye Vody airport.

Dangerous atmospheric phenomena include lightning. They kill people, livestock, cause fires, and damage the power grid. About 10,000 people die from thunderstorms and their consequences every year around the world. Moreover, in some areas of Africa, France and the USA, the number of victims from lightning is greater than from other natural phenomena. The annual economic damage from thunderstorms in the United States is at least $700 million.

Droughts are typical for desert, steppe and forest-steppe regions. A lack of precipitation causes drying out of the soil, a decrease in the level of groundwater and in reservoirs until they dry out completely. Moisture deficiency leads to the death of vegetation and crops. Droughts are especially severe in Africa, the Near and Middle East, Central Asia and southern North America.

Droughts change human living conditions and have an adverse effect on the natural environment through processes such as soil salinization, dry winds, dust storms, soil erosion and forest fires. Fires are especially severe during drought in taiga regions, tropical and subtropical forests and savannas.

Droughts are short-term processes that last for one season. When droughts last more than two seasons, there is a threat of famine and mass mortality. Typically, drought affects the territory of one or more countries. Prolonged droughts with tragic consequences occur especially often in the Sahel region of Africa.

Atmospheric phenomena such as snowfalls, short-term heavy rains and prolonged lingering rains cause great damage. Snowfalls cause massive avalanches in the mountains, and rapid melting of fallen snow and prolonged rainfall lead to floods. The huge mass of water falling on the earth's surface, especially in treeless areas, causes severe soil erosion. There is an intensive growth of gully-beam systems. Floods occur as a result of large floods during periods of heavy precipitation or high water after sudden warming or spring melting of snow and, therefore, are atmospheric phenomena in origin (they are discussed in the chapter on the ecological role of the hydrosphere).

Weathering- destruction and change of rocks under the influence of temperature, air, water. A set of complex processes of qualitative and quantitative transformation of rocks and their constituent minerals, leading to the formation of weathering products. Occurs due to the action of the hydrosphere, atmosphere and biosphere on the lithosphere. If rocks remain on the surface for a long time, then as a result of their transformations a weathering crust is formed. There are three types of weathering: physical (ice, water and wind) (mechanical), chemical and biological.

Physical weathering

The greater the temperature difference during the day, the faster the weathering process occurs. The next step in mechanical weathering is the entry of water into the cracks, which, when frozen, increases in volume by 1/10 of its volume, which contributes to even greater weathering of the rock. If blocks of rock fall, for example, into a river, then there they are slowly ground down and crushed under the influence of the current. Mudflows, wind, gravity, earthquakes, and volcanic eruptions also contribute to the physical weathering of rocks. Mechanical crushing of rocks leads to the passage and retention of water and air by the rock, as well as a significant increase in surface area, which creates favorable conditions for chemical weathering. As a result of cataclysms, rocks can crumble from the surface, forming plutonic rocks. All the pressure on them is exerted by the side rocks, which is why the plutonic rocks begin to expand, which leads to the disintegration of the upper layer of rocks.

Chemical weathering

Chemical weathering is a combination of various chemical processes, as a result of which further destruction of rocks occurs and a qualitative change in their chemical composition with the formation of new minerals and compounds. The most important factors in chemical weathering are water, carbon dioxide and oxygen. Water is an energetic solvent of rocks and minerals. The main chemical reaction of water with minerals of igneous rocks is hydrolysis, which leads to the replacement of cations of alkali and alkaline earth elements of the crystal lattice with hydrogen ions of dissociated water molecules:

KAlSi3O8+H2O→HAlSi3O8+KOH

The resulting base (KOH) creates an alkaline environment in the solution, in which further destruction of the orthoclase crystal lattice occurs. In the presence of CO2, KOH changes to carbonate form:

2KOH+CO2=K2CO3+H2O

The interaction of water with rock minerals also leads to hydration - the addition of water particles to mineral particles. For example:

2Fe2O3+3H2O=2Fe2O 3H2O

In the zone of chemical weathering, oxidation reactions are also widespread, to which many minerals containing metals capable of oxidation are subjected. A striking example of oxidative reactions during chemical weathering is the interaction of molecular oxygen with sulfides in an aquatic environment. Thus, during the oxidation of pyrite, along with sulfates and hydrates of iron oxides, sulfuric acid is formed, which participates in the creation of new minerals.

2FeS2+7O2+H2O=2FeSO4+H2SO4;

12FeSO4+6H2O+3O2=4Fe2(SO4)3+4Fe(OH)3;

2Fe2(SO4)3+9H2O=2Fe2O3 3H2O+6H2SO4

Radiation weathering

Radiation weathering is the destruction of rocks under the influence of radiation. Radiation weathering influences the process of chemical, biological and physical weathering. A typical example of a rock significantly susceptible to radiation weathering is lunar regolith.

Biological weathering

Biological weathering is produced by living organisms (bacteria, fungi, viruses, burrowing animals, lower and higher plants). In the process of their life activity, they affect rocks mechanically (destruction and crushing of rocks by growing plant roots, when walking, digging holes by animals).Especially Microorganisms play a major role in biological weathering.

Weathering products

The product of weathering in a number of areas of the Earth on the surface is kurum. The products of weathering under certain conditions are crushed stone, debris, “slate” fragments, sand and clay fractions, including kaolin, loess, and individual rock fragments of various shapes and sizes depending on the petrographic composition, time and weathering conditions.

Air masses- large volumes of air in the lower part of the earth's atmosphere - the troposphere, having horizontal dimensions of many hundreds or several thousand kilometers and vertical dimensions of several kilometers, characterized by approximately uniform temperature and moisture content horizontally.

Kinds:Arctic or Antarctic air(AB), Temperate air(UV), tropical air(TV), Equatorial air(EV).

Air in ventilation layers can move in the form laminar or turbulent flow. Concept "laminar" means that the individual air flows are parallel to each other and move in the ventilation space without turbulence. When turbulent flow its particles not only move in parallel, but also perform transverse movement. This leads to vortex formation throughout the entire cross-section of the ventilation duct.

The condition of the air flow in the ventilation space depends on: Air flow speed, Air temperature, Cross-sectional area of ​​the ventilation duct, Shapes and surfaces of building elements at the boundary of the ventilation duct.

In the earth's atmosphere, air movements of the most varied scales are observed - from tens and hundreds of meters (local winds) to hundreds and thousands of kilometers (cyclones, anticyclones, monsoons, trade winds, planetary frontal zones).
The air is constantly moving: it rises - upward movement, falls - downward movement. The movement of air in a horizontal direction is called wind. The cause of wind is the uneven distribution of air pressure on the Earth's surface, which is caused by the uneven distribution of temperature. In this case, the air flow moves from places with high pressure to the side where the pressure is less.
When there is wind, the air does not move evenly, but in shocks and gusts, especially near the surface of the Earth. There are many reasons that influence the movement of air: friction of the air flow on the surface of the Earth, encountering obstacles, etc. In addition, air flows, under the influence of the rotation of the Earth, are deflected to the right in the northern hemisphere, and to the left in the southern hemisphere.

Invading areas with different surface thermal properties, air masses are gradually transformed. For example, temperate sea air, entering land and moving inland, gradually heats up and dries out, turning into continental air. The transformation of air masses is especially characteristic of temperate latitudes, into which warm and dry air from tropical latitudes and cold and dry air from subpolar latitudes invade from time to time.

The atmosphere is heterogeneous. In its composition, especially near the earth's surface, air masses can be distinguished.

Air masses are separate large volumes of air that have certain general properties (temperature, humidity, transparency, etc.) and move as one. However, within this volume the winds may be different. The properties of the air mass are determined by the area of ​​its formation. It acquires them in the process of contact with the underlying surface over which it forms or lingers. Air masses have different properties. For example, the air of the Arctic has low temperatures, and the air of the tropics has high temperatures in all seasons of the year; the air of the North Atlantic differs significantly from the air of the Eurasian mainland. The horizontal dimensions of air masses are enormous, they are comparable to continents and oceans or their large parts. There are main (zonal) types of air masses that form in zones with different atmospheric pressure: Arctic (Antarctic), temperate (polar), tropical and equatorial. Zonal air masses are divided into marine and continental - depending on the nature of the underlying surface in the area of ​​their formation.

Arctic air forms over the Arctic Ocean, and in winter also over northern Eurasia and North America. The air is characterized by low temperature, low moisture content, good visibility and stability. Its invasions into temperate latitudes cause significant and sharp cold snaps and lead to predominantly clear and partly cloudy weather. Arctic air is divided into the following types.

Maritime Arctic air (MAA) - forms in the warmer European Arctic, free of ice, with higher temperatures and higher moisture content. Its invasions of the mainland in winter cause warming.

Continental Arctic air (kAv) - forms over the Central and Eastern icy Arctic and the northern coast of the continents (in winter). The air has very low temperatures and low moisture content. The invasion of KAV onto the mainland causes severe cooling in clear weather and good visibility.

The analogue of Arctic air in the Southern Hemisphere is Antarctic air, but its influence extends mainly to adjacent sea surfaces, less often to the southern tip of South America.

Temperate (polar) air. This is air of temperate latitudes. It also distinguishes two subtypes. Continental temperate air (CTA), which forms over vast continental surfaces. In winter it is very cool and stable, the weather is usually clear with severe frosts. In summer it warms up greatly, rising currents arise in it, clouds form, rain often falls, and thunderstorms are observed. Marine temperate air (MMA) is formed in the middle latitudes over the oceans, and is transported to the continents by westerly winds and cyclones. It is characterized by high humidity and moderate temperatures. In winter, the weather brings cloudy weather, heavy rainfall and increased temperatures (thaws). In summer it also brings large clouds and rain; the temperature decreases during its invasion.

Temperate air penetrates into polar, as well as subtropical and tropical latitudes.

Tropical air is formed in tropical and subtropical latitudes, and in summer - in continental regions in the south of temperate latitudes. There are two subtypes of tropical air. Continental tropical air (CTA) is formed over land and is characterized by high temperatures, dryness and dustiness. Tropical marine air (mTa) is formed over tropical waters (tropical ocean zones) and is characterized by high temperature and humidity.

Tropical air penetrates into temperate and equatorial latitudes.

Equatorial air is formed in the equatorial zone from tropical air brought by the trade winds. It is characterized by high temperatures and high humidity throughout the year. In addition, these qualities are preserved both over land and over the sea, therefore equatorial air is not divided into marine and continental subtypes.

Air masses are in continuous movement. Moreover, if air masses move to higher latitudes or to a colder surface, they are called warm, as they bring warming. Air masses moving to lower latitudes or to a warmer surface are called cold. They bring cold weather.

Moving to other geographical areas, air masses gradually change their properties, primarily temperature and humidity, i.e. transform into air masses of another type. The process of transforming air masses from one type to another under the influence of local conditions is called transformation. For example, tropical air, penetrating towards the equator and into temperate latitudes, is transformed, respectively, into equatorial and temperate air. Temperate sea air, once in the depths of the continents, cools in winter, heats up in summer and always dries out, turning into continental temperate air.

All air masses are interconnected in the process of their constant movement, in the process of general circulation of the troposphere.