atmospheric fronts. Cyclones and anticyclones

cold VM weather

Warm VM weather

A warm VM, moving to a cold region, becomes stable (cooling from the cold underlying surface). The air temperature, falling, can reach the level of condensation with the formation of haze, fog, low stratus clouds with precipitation in the form of drizzle or small snowflakes.

Flight conditions in a warm airframe in winter:

Light and moderate icing in clouds at low temperatures;

Cloudless sky, good visibility at H = 500-1000 m;

Weak chatter at H = 500-1000 m.

In the warm season, the conditions for flights are favorable, except for areas with separate centers of thunderstorms.

When moving to a warmer region, the cold VM heats up from below and becomes unstable VM. Powerful ascending air movements contribute to the formation of cumulonimbus clouds with heavy precipitation, thunderstorms.

atmospheric front- this is the section between two air masses that differ from one another in physical properties (temperature, pressure, density, humidity, cloudiness, precipitation, wind direction and speed). The fronts are located in two directions - horizontally and vertically.

The boundary between air masses along the horizon is called front line, the boundary between air masses along the vertical - called. frontal zone. The frontal zone is always inclined towards cold air. Depending on which VM comes - warm or cold, they distinguish warm TF and cold HF fronts.

characteristic feature fronts is the presence of the most dangerous (difficult) meteorological conditions for the flight. Frontal cloud systems are characterized by significant vertical and horizontal extent. Thunderstorms, turbulence, icing are observed on the fronts in the warm season, fogs, snowfall, and low clouds are observed in the cold season.

warm front is a front that moves in the direction of cold air, followed by warming.

A powerful cloud system is associated with the front, consisting of cirrostratus, altostratus, nimbostratus clouds, formed as a result of the rise of warm air along a cold wedge. SMU on the TF: low cloudiness (50-200m), fog ahead of the front, poor visibility in the precipitation zone, icing in the clouds and precipitation, ice on the ground.

The conditions of flight through the TF are determined by the height of the lower and upper boundaries of the clouds, the degree of stability of the VM, the temperature distribution in the cloud layer, moisture content, terrain, time of year, day.

1. If possible, stay in the zone of negative temperatures as little as possible;

2. Cross the front perpendicular to its location;

3. Choose a flight profile in the zone of positive temperatures, i.e. below the 0° isotherm, and if the temperature is below zero in the entire zone, the flight should be carried out where the temperature is below -10°. When flying from 0° to -10°, the most intense icing is observed.

When meeting with dangerous MU (thunderstorm, hail, heavy icing, heavy turbulence), you must return to the departure airfield or land at an alternate airfield.

- cold front - This is a section of the main front moving towards high temperatures, followed by cooling. There are two types of cold fronts:

-Cold front of the first kind (HF-1r)- this is a front moving at a speed of 20 - 30 km / h. Cold air, flowing like a wedge under warm air, displaces it upwards, forming cumulonimbus clouds, heavy rainfall, and thunderstorms ahead of the front. Part of the TV flows onto the HV wedge, forming layered clouds and extensive precipitation behind the front. Heavy turbulence ahead of the front, poor visibility behind the front. The conditions of flight through the HF -1p are similar to the conditions for crossing the TF.

At the intersection of HF -1r, one can meet a weak and moderate turbulence, where warm air is displaced by cold air. Flying at low altitudes can be hampered by low clouds and poor visibility in the rain zone.

Cold front of the second kind (HF - 2p) - This is a front moving fast at a speed = 30 - 70 km/h. Cold air quickly flows under warm air, displacing it vertically upwards, forming vertically developed cumulonimbus clouds in front of the front, heavy rainfall, thunderstorms, and squalls. It is forbidden to cross the KhF - the 2nd kind due to strong turbulence, a flurry of thunderstorm activity, a strong development of cloudiness along the vertical - 10 - 12 km. The width of the front near the ground is from tens to hundreds of kilometers. As the front passes, the pressure increases.

Under the influence of downward flows in the front, after its passage, a clearing occurs. Subsequently, the cold air, falling on the warm underlying surface, becomes unstable, forming cumulus, powerful cumulus, cumulonimbus clouds with showers, thunderstorms, squalls, strong turbulence, wind shear, and secondary fronts are formed.

Secondary fronts - These are fronts that form within the same VM and separate areas with warmer and colder air. The flight conditions in them are the same as on the main fronts, but weather phenomena are less pronounced than on the main fronts, but here you can also find low clouds, poor visibility due to precipitation (blizzards in winter). Thunderstorms, heavy rainfall, squalls, and wind shear are associated with secondary fronts.

Stationary fronts - these are fronts that remain motionless for some time, are located parallel to the isobars. The cloud system is similar to TF clouds, but with a small horizontal and vertical extent. Fog, ice, icing can occur in the front zone.

Upper fronts this is the state when the surface of the front does not reach the surface of the earth. This happens if a strongly cooled layer of air is encountered on the path of the front or the front is washed out in the surface layer, and difficult weather conditions (jet, turbulence) still persist at heights.

Fronts of occlusion formed as a result of the merging of cold and warm fronts. When the fronts close, their cloud systems close. The process of closure of TF and HF begins in the center of the cyclone, where HF, moving at a higher speed, overtakes the TF, gradually spreading to the periphery of the cyclone. Three VMs are involved in the formation of the front: - two cold and one warm. If the air behind the HF is less cold than before the TF, then when the fronts close, a complex front is formed, called WARM FRONT OCCLUSION.

If the air mass behind the front is colder than the front, then the rear part of the air will flow under the front, which is warmer. Such a complex front is called COLD FRONT OF OCCLUSION.

Weather conditions on occlusion fronts depend on the same factors as on the main fronts: - the degree of VM stability, moisture content, heights of the lower and upper cloud boundaries, terrain, season, day. At the same time, the weather conditions of cold occlusion in the warm season are similar to the weather conditions of the HF, and the weather conditions of warm occlusion in the cold season are similar to the weather of the TF. Under favorable conditions, occlusion fronts can turn into main fronts - warm occlusion in the TF, cold occlusion into a cold front. The fronts move along with the cyclone, turning counterclockwise.

The lowest part of the Earth's atmosphere, the troposphere, is located in in constant motion, moving over the surface of the planet and mixing. Its individual sections have different temperatures. When such atmospheric zones meet, atmospheric fronts arise, which are boundary zones between air masses of different temperatures.

Formation of an atmospheric front

The circulation of tropospheric currents causes warm and cold air currents to meet. At the place of their meeting, due to the temperature difference, active condensation of water vapor occurs, which leads to the formation of powerful clouds, and subsequently to heavy precipitation.

The boundary of atmospheric fronts is rarely even, it is always tortuous and inhomogeneous, due to the fluidity of air masses. Warmer atmospheric currents flow on cold air masses and rise up, colder ones displace warm air, forcing it to rise higher.

Rice. 1. Approach of the atmospheric front.

Warm air is lighter than cold air and always rises, cold air, on the contrary, accumulates near the surface.

Active fronts move at an average speed of 30-35 km. per hour, but they can temporarily stop their movement. Compared with the volume of air masses, the boundary of their contact, which is called the atmospheric front, is very small. Its width can reach hundreds of kilometers. In length - depending on the magnitude of the colliding air currents, the front can be thousands of kilometers long.

Signs of a weather front

Depending on which atmospheric current moves more actively, warm and cold fronts are distinguished.

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Rice. 2. Synoptic map of atmospheric fronts.

Signs of an approaching warm front are:

• movement of warm air masses towards colder ones;
• formation of cirrus or stratus clouds;
• gradual weather change;
• drizzling or heavy rains;
• rise in temperature after the passage of the front.

The approach of a cold front is evidenced by:

• movement of cold air towards warm regions of the atmosphere;
• education a large number cumulus clouds;
• rapid weather changes;
• torrential and thunderstorms;
• subsequent decrease in temperature.

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Cold air moves faster than warm air, so cold fronts are more active.

Weather and atmospheric front

In areas where atmospheric fronts pass, the weather changes.

Rice. 3. Collision of warm and cold air currents.

Its changes depend on:

• temperatures of the air masses encountered . How more difference temperatures - the stronger the winds, the more intense the precipitation, the more powerful the clouds. And vice versa, if the temperature difference of air currents is small, then the atmospheric front will be weakly expressed and its passage over the Earth's surface will not bring any special weather changes;
• air current activity . Depending on their pressure, atmospheric flows can have different speeds of movement, on which the rate of weather change will depend;
• front shapes . The simpler linear forms of the front surface are more predictable. With the formation of atmospheric waves or the closure of individual outstanding tongues of air masses, vortices are formed - cyclones and anticyclones.

After the passage of a warm front, weather with a higher temperature sets in. After the passage of the cold - there is a cooling.

What have we learned?

Atmospheric fronts are border areas between air masses with different temperatures. The greater the temperature difference, the more intense the weather change will be during the passage of the front. The approach of a warm or cold front can be distinguished by the shape of the clouds and the type of precipitation.

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At first glance, the air in the atmosphere appears to be stationary. In fact, movement occurs continuously in both vertical and horizontal directions. In motion, huge air masses interact with each other. Their dimensions are commensurate with the areas of the continents. This is the basis of such a phenomenon as an atmospheric front.

The air in such an array has uniform properties, obtained when it originates above the surface of the land or the ocean, where it was formed. Air vortices of the Earth move the air of the troposphere from one territory to another, transferring and changing their properties along with them. The behavior and properties of air masses determine the types of climate and weather features of the territory.

Classification of air masses

Depending on the properties, air masses are divided into types. The main classification criterion is the ratio of heat and moisture:

• cold and dry - the air of the Arctic and Antarctic;
• change the temperature and humidity according to the seasons of the year - polar (temperate latitudes);
• hot and dry - tropical;
• hot and humid - equatorial.

When moving, air masses collide, and atmospheric events rapidly develop on their border.

Atmospheric front - definition

Geography is a science that studies various natural phenomena. The concept of an atmospheric front is also considered here. It can be very extensive: several tens of kilometers long, hundreds of meters high and thousands of kilometers long. The transition zone from one property to another is called the frontal surface, and its intersection with the earth's surface is called the front line. It unfolds the main events, accompanied by sudden changes in the weather. The weather conditions will depend on what kind of air the front brought.

Thus, the atmospheric front in geography is the boundary between air masses of different properties.

The difference of atmospheric fronts from each other is due not only to air temperature, but also to how they are generated.

warm front

It is formed when light warm air at a higher speed catches up with a cold mass, which, due to gravity, is not able to move quickly. Upon contact with cold air, warm air begins to creep up the gentle slope formed by the cold massif. Already two air masses together continue to move in the direction where the warm air moved. As the warm air rises, it cools and forms rain clouds.

A warm atmospheric front can always be recognized by the following features:

• barometers show a decline atmospheric pressure;
• there is an increase in air temperature;
• harbingers of rain appear - cirrus clouds, gradually turning into cirrostratus, and then - into altostratus;
• the wind intensifies, changing its direction;
• the clouds are filled with heaviness;
• precipitation falls.

Warming is a constant companion of the warm front. In summer, precipitation is prolonged, so rainy, albeit warm, weather sets in. In winter, the arrival of a warm front is associated with heavy snowfalls and thaws.

cold front

An atmospheric cold front occurs when cold air in motion catches up with warm air, picks it up and rapidly lifts it up. Due to its lightness, warm air quickly rises to a high altitude, and also cools quickly. Moisture from warm air turns into steam and forms clubs of cumulonimbus clouds. The air continues to move in the direction that the cold air moved. Always accompanied by showers and cooling.

Characteristic features of a cold front:

• there are pressure surges both behind the front line and in front of it;
• cumulus clouds appear;
• a squally wind is blowing, sharply changing direction from left to right;
• a downpour begins with a thunderstorm, hail is possible, precipitation can last several hours;
• it gets colder, the temperature difference can be up to 10 0 С;
• clearings are visible behind the cloud line.

The weather that accompanies a cold front is always a challenge, especially for those who are on the road.

Depending on the intensity of air movement, an atmospheric front of the 1st kind is distinguished, characterized by slow movement, and a front of the 2nd kind, moving rapidly and bringing rain and squally wind in summer, and snowfalls and blizzards in winter. They also differ in the speed of atmospheric processes taking place inside.

Fronts of occlusion

These are areas of connection of several fronts. They are also warm and cold. The mechanism of their formation is complex and depends on the properties of the air encountered. As a rule, two cold massifs and one warm massif participate in their formation, and vice versa.

With occlusion fronts, the following are observed:

• overcast and heavy rains;
• not an increase, but a change in wind direction;
• lack of jumps in atmospheric pressure;
• temperature constancy;
• the formation of cyclones.

Cyclones and anticyclones

Characteristic weather events during the passage of all types of fronts is impossible without mentioning cyclonic and anticyclonic types of weather.

Air over the surface of the planet is distributed unevenly, so it flows from where there is a lot of it to areas where there is not enough air. As a result, there is a difference in air pressure across earth's surface. When air masses flow in the atmosphere, vortices are formed.

An air funnel with low pressure in the center is called a cyclone, and with high pressure - an anticyclone. Cloudy, snowy or rainy weather is called cyclonic, dry and clear weather is called anticyclonic, frosty in winter.

Geographic atmospheric differences

The geographical classification of atmospheric fronts is based on two features:

• geographic latitudes in which the formation of frontal zones occurs;
• front-forming (atmospheric) underlying surface.

On the border climatic zones, differing by dominant air masses, belts of frontal zones are formed. There are three of them on the globe:

1. In the polar zone of the Northern and Southern Hemispheres, at the border of cold polar and temperate air masses, the Arctic (in the Northern Hemisphere) and Antarctic (in the Southern Hemisphere) frontal zones formed.
2. An atmospheric polar front has formed between temperate and tropical latitudes. He encircles Earth in the region of the northern and southern tropics.
3. The tropical frontal zone is located on the border of tropical and equatorial air.

Depending on the season, the zones shift in the meridional direction. Circulation processes in geographic frontal zones form climatic zones.

Underlying surface and frontal zones

Dry continental air masses form over the continent, and wet sea masses form over the ocean. In the process of atmospheric circulation, they also collide, frontal zones are formed at the boundary, in which the properties of the air are transformed. Marine and continental atmospheric fronts are formed. The types of weather associated with them depend on the properties of the air.

So, we have dealt with such a concept as an atmospheric front, the definition of which is as follows - this is the line of contact of air masses different types. The properties of the atmospheric front depend on the direction in which the air masses move relative to each other. The passage of atmospheric fronts is always accompanied by changes in weather conditions and atmospheric phenomena characteristic of each front.

Watching the weather changes is very exciting. The sun gives way to rain, the rain to snow, and gusty winds blow over all this diversity. In childhood, this causes admiration and surprise, in older people - a desire to understand the mechanism of the process. Let's try to understand what shapes the weather and how atmospheric fronts are related to it.

air mass boundary

In the usual perception, "front" is a military term. This is the edge on which the clash of enemy forces takes place. And the concept of atmospheric fronts is the boundaries of contact between two air masses that form over huge areas of the Earth's surface.

By the will of nature, man got the opportunity to live, evolve and populate everything large territories. The troposphere - the lower part of the Earth's atmosphere - provides us with oxygen and is in constant motion. All of it consists of separate air masses, united by a common occurrence and similar indicators. Among the main indicators of these masses determine the volume, temperature, pressure and humidity. During the movement, different masses can approach and collide. However, they never lose their boundaries and do not mix with each other. - these are areas where sharp weather jumps come into contact and occur.

A bit of history

The concepts of "atmospheric front" and "frontal surface" did not arise by themselves. They were introduced into meteorology by the Norwegian scientist J. Bjerknes. It happened in 1918. Bjerknes proved that atmospheric fronts are the main links in the high and middle layers. However, before the research of the Norwegian, back in 1863, Admiral Fitzroy suggested that violent atmospheric processes begin at the meeting places of air masses coming from different parts of the world. But at that moment, the scientific community did not pay attention to these observations.

The Bergen school, of which Bjerknes was a representative, not only carried out its own observations, but also brought together all the knowledge and assumptions expressed by earlier observers and scientists, and presented them in the form of a consistent scientific system.

By definition, the inclined surface, which is the transition area between different air flows, is called the frontal surface. But atmospheric fronts are a display of frontal surfaces on a meteorological map. Usually, the transition region of the atmospheric front is tied up near the surface of the Earth and rises up to those heights at which the differences between air masses are blurred. Most often, the threshold of this height is from 9 to 12 km.

warm front

Atmospheric fronts are different. They depend on the direction of movement of warm and cold massifs. There are three types of fronts: cold, warm and occlusion, formed at the junction of different fronts. Let us consider in more detail what warm and cold atmospheric fronts are.

A warm front is a movement of air masses in which cold air gives way to warm air. That is, the air is more high temperature, advancing, is located in the territory dominated by cold air masses. In addition, it rises up along the transition zone. At the same time, the air temperature gradually decreases, due to which condensation of the water vapor in it occurs. This is how clouds form.

The main signs by which you can identify a warm atmospheric front:

• atmospheric pressure drops sharply;
• increases;
• the air temperature rises;
• cirrus appear, then cirrostratus, and after - high-stratus clouds;
• the wind turns slightly to the left and becomes stronger;
• clouds become nimbostratus;
• precipitation of varying intensity falls.

It usually warms up after the precipitation stops, but this does not last long, because the cold front moves very quickly and catches up with the warm atmospheric front.

cold front

Such a feature is observed: a warm front is always inclined in the direction of movement, and a cold front is always inclined in the opposite direction. When fronts move, cold air wedges into warm air, pushing it up. Cold atmospheric fronts lead to a decrease in temperature and cooling over a large area. As the rising warm air masses cool, the moisture condenses into clouds.

The main signs by which a cold front can be identified are:

• before the front, the pressure drops, behind the line of the atmospheric front it rises sharply;
• cumulus clouds form;
• a gusty wind appears, with a sharp change in direction clockwise;
• heavy rain begins with a thunderstorm or hail, the duration of precipitation is about two hours;
• the temperature drops sharply, sometimes by 10 ° C at once;
• Numerous clearings are observed behind the atmospheric front.

Traveling through a cold front is no easy task for travelers. Sometimes you have to overcome whirlwinds and squalls in conditions of poor visibility.

Front of occlusions

It has already been said that atmospheric fronts are different, if everything is more or less clear with warm and cold fronts, then the front of occlusions raises a lot of questions. The formation of such effects occurs at the junction of cold and warm fronts. The warmer air is forced upward. The main action occurs in cyclones at the moment when a more rapid cold front catches up with a warm one. As a result, there is a movement of atmospheric fronts and a collision of three air masses, two cold and one warm.

The main features by which you can determine the front of occlusions:

• clouds and precipitation of a general type;
• abrupt shifts without a strong change in speed;
• smooth pressure change;
• no sudden temperature changes;
• cyclones.

The occlusion front depends on the temperature of the cold air masses in front of it and behind it. Distinguish between cold and warm occlusion fronts. The most difficult conditions are observed at the moment of direct closure of the fronts. As the warm air is displaced, the front is eroded and improved.

Cyclone and anticyclone

Since the concept of "cyclone" was used in the description of the front of occlusions, it is necessary to tell what kind of phenomenon it is.

Due to the uneven distribution of air in the surface layers, zones of high and low pressure. High pressure zones are characterized by excess air, low - insufficient air. As a result of the air flow between the zones (from excess to insufficient), wind is formed. A cyclone is an area of ​​low pressure that draws in, like a funnel, the missing air and clouds from areas where they are in excess.

An anticyclone is an area of ​​high pressure that pushes excess air into areas of low pressure. The main characteristic is clear weather, since clouds are also forced out of this zone.

Geographic division of atmospheric fronts

Depending on the climatic zones, over which atmospheric fronts are formed, they are divided geographically into:

1. Arctic, separating cold Arctic air masses from temperate ones.
2. Polar, located between the temperate and tropical masses.
3. Tropical (trade wind), delimiting the tropical and equatorial zones.

Influence of the underlying surface

On physical properties air masses are affected by radiation and the appearance of the Earth. Since the nature of such a surface can be different, the friction against it occurs unevenly. Difficult geographic topography can deform the atmospheric front line and change its effects. For example, there are known cases of destruction of atmospheric fronts when crossing mountain ranges.

Air masses and atmospheric fronts bring many surprises to forecasters. Comparing and studying the directions of mass movement and the vagaries of cyclones (anticyclones), they make graphs and forecasts that people use every day, without even thinking about how much work is behind it.

The weather in our country is unstable. This is especially evident in the European part of Russia. This is due to the fact that different air masses meet: warm and cold. Air masses differ in properties: temperature, humidity, dust content, pressure. Atmospheric circulation allows air masses to move from one part to another. Where air masses of different properties come into contact, atmospheric fronts.

Atmospheric fronts are inclined to the Earth's surface, their width reaches from 500 to 900 km, and they extend for 2000-3000 km in length. In the frontal zones, there is an interface between two types of air: cold and warm. Such a surface is called frontal. As a rule, this surface is inclined towards cold air - it is located under it as a heavier one. And warm air, lighter, is located above the frontal surface (see fig. 1).

Rice. 1. Atmospheric fronts

The line of intersection of the frontal surface with the surface of the Earth forms front line, which is also briefly called front.

atmospheric front- transitional zone between two dissimilar air masses.

Warm air, being lighter, rises. Rising, it cools, saturated with water vapor. Clouds form and precipitation falls. Therefore, the passage of an atmospheric front is always accompanied by precipitation.

Depending on the direction of movement, moving atmospheric fronts are divided into warm and cold. warm front formed when warm air flows into cold air. The front line moves in the direction of cold air. After the passage of a warm front, warming occurs. The warm front forms a continuous band of clouds hundreds of kilometers long. There are long drizzling rains, and warming comes. The rise of air during the onset of a warm front occurs more slowly compared to a cold front. Cirrus and cirrostratus clouds forming high in the sky are a harbinger of an approaching warm front. (see Fig. 2).

Rice. 2. Warm atmospheric front ()

It is formed when cold air leaks under warm air, while the front line moves towards warm air, which is forced upward. As a rule, a cold front moves very quickly. This causes strong winds, heavy, often heavy rainfall with thunderstorms, and blizzards in winter. After the passage of a cold front, a cold snap sets in. (See Fig. 3).

Rice. 3. Cold front ()

Atmospheric fronts are stationary and moving. If air currents do not move towards cold or towards warm air along the front line, such fronts are called stationary. If the air currents have a movement velocity perpendicular to the front line and move either towards cold or towards warm air, such atmospheric fronts are called moving. Atmospheric fronts arise, move and collapse in about a few days. The role of frontal activity in climate formation is more pronounced in temperate latitudes; therefore, unstable weather is typical for most of Russia. The most powerful fronts occur when the main types of air masses come into contact: arctic, temperate, tropical (see Fig. 4).

Rice. 4. Formation of atmospheric fronts in Russia

Zones reflecting their long-term positions are called climate fronts. On the border between arctic and temperate air, over the northern regions of Russia, a arctic front. Air masses of temperate latitudes and tropical ones are separated by a polar temperate front, which is located mainly to the south of the borders of Russia. The main climatic fronts do not form continuous strips of lines, but are broken into segments. Long-term observations have shown that the Arctic and Polar fronts are shifting southward in winter and northward in summer. In the east of the country, the Arctic front reaches the coast of the Sea of ​​Okhotsk in winter. To the northeast of it, very cold and dry arctic air dominates. IN European Russia the arctic front does not move that far. This is where the warming effect of the North Atlantic Current comes into play. The branches of the polar climate front stretch over the southern territories of our country only in summer, in winter they lie over mediterranean sea and Iran and occasionally capture the Black Sea.

In the interaction of air masses take part cyclones And anticyclones- large moving atmospheric vortices carrying atmospheric masses.

An area of ​​low atmospheric pressure with a specific pattern of winds blowing from the edges towards the center and deviating counterclockwise.

An area of ​​high atmospheric pressure with a specific pattern of winds blowing from the center to the edges and deviating clockwise.

Cyclones are impressive in size, extend into the troposphere to a height of up to 10 km, and a width of up to 3000 km. Pressure increases in cyclones and decreases in anticyclones. In the northern hemisphere, the winds blowing towards the center of the cyclones are deflected by the force of the axial rotation of the earth to the right (the air spins counterclockwise), and in the central part the air rises. In anticyclones, the winds directed to the outskirts also deviate to the right (the air swirls clockwise), and in the central part the air descends from the upper layers of the atmosphere down (see fig. 5, fig. 6).

Rice. 5. Cyclone

Rice. 6. Anticyclone

The fronts on which cyclones and anticyclones originate are almost never rectilinear, they are characterized by wavy bends. (See Fig. 7).

Rice. 7. Atmospheric fronts (synoptic map)

In the formed bays of warm and cold air, rotating tops are formed atmospheric vortices (see fig. 8).

Rice. 8. Formation of an atmospheric vortex

Gradually, they separate from the front and begin to move and carry air on their own at a speed of 30-40 km / h.

Atmospheric vortices live for 5-10 days before destruction. And the intensity of their formation depends on the properties of the underlying surface (temperature, humidity). Several cyclones and anticyclones form daily in the troposphere. There are hundreds of them throughout the year. Every day our country is under the influence of some kind of atmospheric vortex. Since the air rises in cyclones, cloudy weather with precipitation and winds is always associated with their arrival, cool in summer and warm in winter. During the entire stay of the anticyclone, cloudless dry weather prevails, hot in summer and frosty in winter. This is facilitated by the slow sinking of air down from the higher layers of the troposphere. The descending air heats up and becomes less saturated with moisture. In anticyclones, the winds are weak, and in their inner parts there is complete calm - calm(see fig. 9).

Rice. 9. Air movement in an anticyclone

In Russia, cyclones and anticyclones are confined to the main climatic fronts: polar and arctic. They also form on the border between maritime and continental air masses of temperate latitudes. In the west of Russia, cyclones and anticyclones arise and move in the direction of the general air transport from west to east. In the Far East, in accordance with the direction of the monsoons. When moving with westward transfer in the east, cyclones deviate to the north, and anticyclones deviate to the south (see fig. 10). Therefore, the paths of cyclones in Russia most often pass through the northern regions of Russia, and anticyclones - through the southern ones. In this regard, the atmospheric pressure in the north of Russia is lower, there can be inclement weather for many days in a row, in the south there are more sunny days, dry summers and winters with little snow.

Rice. 10. Deviation of cyclones and anticyclones when moving from the west

Areas where intense winter cyclones pass: the Barents, Kara, Okhotsk Seas and the northwest of the Russian Plain. In summer, cyclones are most frequent on Far East and in the west of the Russian Plain. Anticyclonic weather prevails throughout the year in the south of the Russian Plain, in the south of Western Siberia, and in winter over the entire Eastern Siberia, where the Asian pressure maximum is established.

The movement and interaction of air masses, atmospheric fronts, cyclones and anticyclones change the weather and affect it. Data on weather changes are applied to special synoptic maps for further analysis of weather conditions on the territory of our country.

The movement of atmospheric vortices leads to a change in the weather. Her condition for each day is recorded on special maps - synoptic(see fig. 11).

Rice. 11. Synoptic map

Weather observations are carried out by an extensive network of meteorological stations. Then the results of the observations are transmitted to the centers of hydrometeorological data. Here they are processed, and weather information is applied to synoptic maps. The maps show atmospheric pressure, fronts, air temperature, wind direction and speed, cloudiness and precipitation. The distribution of atmospheric pressure indicates the position of cyclones and anticyclones. By studying the patterns of the course of atmospheric processes, it is possible to predict the weather. An accurate weather forecast is an exceptionally complex matter, since it is difficult to take into account the whole complex of interacting factors in their constant development. Therefore, even short-term forecasts of the hydrometeorological center are not always justified.

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Homework

1. Why does precipitation fall in the atmospheric front zone?
2. What is the main difference between a cyclone and an anticyclone?