"This conversation about the weather may not be of interest to everyone, but it can attract the attention of the curious. Let's talk a little about cyclones. The concept of" cyclone "in Greek means" whirling. " atmospheric vortex large scale with low pressure in the center. The air in it rotates counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere. Cyclones tend to bring complex weather- cloudiness, precipitation, increased wind, often seasonal phenomena: thunderstorms, fogs, snowstorms, ice, etc. This is due to the peculiarities of pressure distribution and the nature of air circulation.
Under the influence of friction in lower layers atmosphere in the cyclone, air movement is observed, in addition to circular, also from the periphery to the center, and therefore there is a constant vertical, ascending, air movement and its cooling as it rises. As the air cools, it becomes saturated with moisture, clouds are formed in it, giving precipitation and many other weather phenomena. In cyclones, especially near their centers, the pressure difference between the center and the periphery is always large (i.e., the so-called horizontal pressure gradients are large), and, therefore, strong gusty winds are constantly observed.
By their origin, eddies are divided into two main groups: tropical (hurricanes, typhoons) and cyclones temperate latitudes... Homeland tropical vortices are the oceanic expanses in the equatorial region approximately between 10 - 15 ° north and south latitude. The diameters of these giant eddies are several hundred kilometers, and the height is from 5 to 15 km. Tropical cyclones reach temperate latitudes in the period from late June to early October, and are most active in August-October. Distinctive feature cyclones of this group is that they are thermally homogeneous (i.e., there are no temperature contrasts in different parts vortex), a colossal amount of energy is concentrated in them. Moving towards temperate latitudes, tropical cyclones gradually lose their strength and fade. If their paths ran only over the waters of the oceans and their coastal seas, then only sea and ocean vessels caught along the route would be attacked by hurricanes. However, part of the hurricanes hit the coastal areas of the continents and islands, causing great destruction. Storm winds and heavy precipitation are what bring typhoons to the inhabitants of the districts through which they make their long journeys.
Cyclones in temperate latitudes are less dangerous. They occur mainly in areas atmospheric fronts where two different air masses... In the northern hemisphere, the most extensive cyclones are usually observed over the Atlantic and Pacific oceans... Their frequency depends on the season and geographic area. On average in the northern hemisphere, cyclones over European part continent more frequent in winter, over Asian - in summer. Cyclones have a diameter of about 2-3 thousand km or more.
The weather in the cyclone of extratropical latitudes is heterogeneous: the front and rear parts of the cyclone are distinguished, left and right in relation to the direction of its movement. In the front part of the cyclone, continuous layered clouds of a warm front, overburden precipitation with winds from the southern quarter of the horizon prevail. In the rear of the cyclone, behind the cold front, the weather is unstable, with precipitation storm type, gusty winds of the northwestern and northern quarters; cloudiness can be discontinuous and even with short-term clearings, and in summer it will be of a convective type. The left (most often northern) part of the cyclone is characterized by weather conditions that can be called intermediate between the front and rear parts of the cyclone; the winds of the eastern and northeastern quarters prevail, the clouds are solid, the precipitation is massive, falling out intermittently and gradually turning into short-term rainstorms. Right South part For a certain period of its life, a cyclone is a "warm sector" - it is filled with a warm air mass, which is forced upward over time. Here, depending on the season and the type of air mass, the weather can be very different, but mostly it happens without significant precipitation, with fogs or low thin stratus clouds, often cloudless and always warm, with winds from the southern and southwestern quarters. "
Anticyclone(from the Greek. anti - against, instead of; kyklon - whirling, rotating) is an area in the atmosphere characterized by increased air pressure in the center.
The wind in the anticyclone blows around the center in the Northern Hemisphere clockwise, in the South - counterclockwise, thereby forming a giant vortex.
A distinctive feature of anticyclones is a strictly defined wind direction. The wind is directed from the center to the periphery of the anticyclone, that is, in the direction of decreasing air pressure.
Another component of the winds in the anticyclone is the effect of the Coriolis force due to the rotation of the Earth. In the Northern Hemisphere, this leads to a turn of the moving stream to the right. V Southern hemisphere, respectively, to the left. That is why the wind in anticyclones Northern hemisphere moves in the direction of movement of the clockwise, and in the South - vice versa. The reverse wind direction is typical for cyclones.
In a low, cold anticyclone, isobars remain closed only in the lowest kilometers, and in the middle troposphere, increased pressure is not detected at all; the presence of a high-altitude cyclone above such an anticyclone is also possible. The high anticyclone is warm and retains closed isobars with anticyclonic circulation even in the upper troposphere. Sometimes the anticyclone is multicenter.
On pressure distribution maps, the anticyclone is represented by concentric closed isobars (lines of equal pressure) of irregular, approximately oval shape. Highest pressure- in the center of the anticyclone and decreases towards the periphery.
The pressure in the center of the anticyclone at sea level rises to 1020-1040 mbar, and sometimes (for example, in winter in Asia) - up to 1080 mbar (with an average pressure at sea level of 1010-1015 mbar).
Anticyclones develop daily in the troposphere (lower atmosphere) along with cyclones. Both are parts general circulation atmosphere, creating inter-latitudinal air exchange. Over the course of a year, many hundreds of them appear over each hemisphere.
The duration of the existence of a separate anticyclone is several days, and sometimes weeks. Like cyclones, anticyclones move in the direction of the general transport of air in the troposphere, i.e. from west to east, while deviating towards low latitudes.
average speed anticyclone movement - about 30 km / h in the Northern Hemisphere and about 40 km / h in the Southern, but often anticyclones take a sedentary state for a long time (blocking anticyclone).
Blocking anticyclone - a practically stationary powerful anticyclone, which has the ability to prevent other air masses from passing into the territory occupied by it. The average lifespan of such an anticyclone is from three to five days, only 1% of anticyclones last up to 15 days.
However, in 1972 and 2010 the anticyclone in summer time(on European territory Russia) existed in both cases for almost two months, causing a catastrophic drought and extreme heat, as well as Forest fires(as a natural phenomenon).
It is the same on Earth permanent anticyclones, this is:
- Azores anticyclone;
- Antarctic anticyclone;
- Bermuda Anticyclone;
- Hawaiian anticyclone;
- Greenland anticyclone;
- Canadian anticyclone;
- North Pacific Anticyclone;
- Siberian anticyclone;
- South Atlantic Anticyclone;
- South Indian anticyclone;
- South Pacific Anticyclone.
Above the so-called friction layer, i.e. on average above 1000 m, the wind in the anticyclone blows almost along the isobars, but in the friction layer it significantly deviates from the isobars outward, at earth surface- at an angle close to 30 °. This spreading of air from the area of the anticyclone in the lower layer is accompanied by its inflow into the anticyclone in the overlying layers of the atmosphere and slow subsidence - subsidence. When settling, the air heats up adiabatically and moves away from the saturation state. Therefore, the temperature of the troposphere in the anticyclone is increased (only over the very surface of the land in winter it can be very low), the cloudiness is low, and precipitation, as a rule, is absent. Winds in the inner part of the anticyclone are weak, but intensify towards the periphery.
As the anticyclone develops and the temperature rises in it, the height of the anticyclone also increases: closed isobars are found for more and more high levels in the troposphere and even in the lower stratosphere. The stratosphere in the anticyclone begins at a higher altitude than in the cyclone, and its temperature is lowered.
Anticyclone signs:
- clear or slightly cloudy weather;
- lack of wind;
- lack of precipitation;
- stable nature of the weather (does not change noticeably over time, as long as the anticyclone exists).
V summer period the anticyclone brings hot, slightly cloudy weather. In winter, the anticyclone brings very coldy, sometimes frosty fog is also possible.
An important feature of anticyclones is their formation in certain areas. In particular, anticyclones are formed over the ice fields. And the thicker the ice cover, the more pronounced the anticyclone; that is why the anticyclone over Antarctica is very powerful, and over Greenland it is shallow, over the Arctic - medium in intensity. Powerful anticyclones also develop in the tropical zone.
Eurasia is an interesting example of abrupt changes in the formation of various air masses. In the summertime over her central regions the region is being formed low pressure where air from neighboring oceans is sucked in. This is especially pronounced in the South and East Asia: an endless string of cyclones carries moist warm air inland.
In winter, the situation changes dramatically: an area is formed over the center of Eurasia high pressure- The Asian maximum, cold and dry winds from the center of which (Mongolia, Tuva, South Siberia), diverging clockwise, carry the cold up to the eastern outskirts of the mainland and cause clear, frosty, almost snowless weather on Far East, in North China. In the western direction, anticyclones influence less intensively. Sharp decreases in temperature are possible only if the center of the anticyclone moves to the west of the observation point, because the wind changes direction from south to north. Similar processes are often observed in the East European Plain.
Anticyclone(from the Greek. anti - against, instead; kyklon - whirling, spinning) is an area in the atmosphere characterized by high air pressure in the center.
The wind blows in the anticyclone, going around the center in the Northern Hemisphere clockwise, in the South - counterclockwise, thus forming a huge vortex.
A distinctive feature of anticyclones is a strictly defined wind direction. The wind is oriented from the center to the periphery of the anticyclone, in other words, in the direction of decreasing air pressure.
Another component of the winds in the anticyclone is the effect of the Coriolis force due to the rotation of the Earth. In the Northern Hemisphere, this leads to a right turn of the moving stream. In the Southern Hemisphere, respectively, to the left. That is why the wind in the anticyclones of the Northern Hemisphere moves in the clockwise direction, and in the South - opposite. For cyclones, the reverse wind direction is typical.
In a cool, low anticyclone, the isobars remain closed exclusively in the lowest kilometers, while in the middle troposphere there is generally no overpressure; there may also be a high-altitude cyclone above such an anticyclone. The highest anticyclone is warm and retains closed isobars with anticyclonic circulation even in the upper troposphere. From time to time, the anticyclone is multicenter.
On the maps of pressure distribution, the anticyclone is represented by concentric closed isobars (lines of equal pressure) of an irregular, approximately round shape. The highest pressure is in the center of the anticyclone and decreases towards the periphery.
The pressure in the center of the anticyclone at sea level increases to 1020-1040 mbar, and from time to time (for example, in winter in Asia) - up to 1080 mbar (with an average pressure at sea level of 1010-1015 mbar).
Anticyclones develop daily in the troposphere (lower atmosphere) together with cyclones. Both are parts of the general circulation of the atmosphere, creating inter-latitudinal air exchange. In the direction of the year, many hundreds of them appear over each hemisphere.
The duration of the existence of a separate anticyclone is a few days, and sometimes weeks. Like cyclones, anticyclones move in the direction of the general transport of air in the troposphere, i.e. from west to east, deviating with all this to low latitudes.
The average speed of movement of the anticyclone is about 30 km / h in the Northern Hemisphere and about 40 km / h in the South, but often anticyclones are forever immobile (blocking anticyclone).
Blocking anticyclone - in fact, an immobile, powerful anticyclone, which has the ability to prevent other air masses from passing to the area occupied by itself. The average lifespan of such an anticyclone is from 3 to 5 days, only 1% of anticyclones last up to 15 days.
But in 1972 and 2010, an anticyclone in summer time (on the European area of Russia) existed in both cases for actually two months, causing a damn drought and the most intense heat, also forest fires (as a natural phenomenon).
Unchanging anticyclones also operate on Earth, these are:
Above the so-called friction layer, i.e. on average, above 1000 m, the wind in the anticyclone blows practically along the isobars, however, in the friction layer it deviates significantly outward from the isobars, at the earth's surface by an angle close to 30 °. This spreading of air from the area of the anticyclone in the lower layer is accompanied by its inflow into the anticyclone in the overlying layers of the atmosphere and unhurried sinking - subsidence. When settling, the air heats up adiabatically and moves away from the saturation state. Therefore, the temperature of the troposphere in the anticyclone is increased (only over the very surface of the land in winter it can be very low), the cloudiness is low, precipitation, most of all, is absent. Winds in the inner part of the anticyclone are weak, but intensify towards the periphery.
As the anticyclone develops and the temperature rises in it, the height of the anticyclone also increases: closed isobars are found at ever higher levels in the troposphere and even in the lower stratosphere. The stratosphere in the anticyclone begins at a higher altitude than in the cyclone, and its temperature is lowered.
Anticyclone signs:
In summer, the anticyclone brings hot, slightly cloudy weather. In winter, the anticyclone brings severe frosts, frosty fog is also likely from time to time.
A fundamental feature of anticyclones is their formation in certain areas. Namely, anticyclones are formed over the ice fields. And the stronger the ice cover, the stronger the anticyclone is; that is why the anticyclone over Antarctica is very powerful, and over Greenland it is shallow, over the Arctic - medium in intensity. Massive anticyclones also develop in the tropical zone.
Eurasia is a fascinating example of abrupt changes in the formation of different air masses. In summer, a low-pressure area forms over its central regions, where air from the adjoining oceans is sucked in. Separately, this is very evident in South and East Asia: an endless series of cyclones carries wet warm air deep into the continent.
In winter, the situation changes dramatically: an area of the highest pressure forms over the center of Eurasia - the Asian maximum, cool and dry winds from the center of which (Mongolia, Tyva, South Siberia), diverging clockwise, carry the cold right to the eastern outskirts of the continent and cause clear, frosty, virtually snowless weather in the Far East, North China. In the western direction, anticyclones have the least active influence. Sharp decreases in temperature are possible only if the center of the anticyclone moves to the west of the observation point, as the wind changes direction from south to north. Similar processes are often observed in the East European Plain.
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At sea level and with appropriate wind distribution. Unlike the cyclone, the wind in the Northern Hemisphere circulates clockwise, and in the Southern Hemisphere in the opposite direction.
In a low anticyclone - cold, isobars remain closed only in the lowest layers of the troposphere (up to 1.5 km), and in the middle troposphere, increased pressure is not detected at all; the presence of a high-altitude cyclone above such an anticyclone is also possible.
The high anticyclone is warm and retains closed isobars with anticyclonic circulation even in the upper troposphere. Sometimes the anticyclone is multicenter. The air in the anticyclone in the Northern Hemisphere moves around the center clockwise (that is, deviating from the baric gradient to the right), in the Southern Hemisphere - counterclockwise.
The anticyclone is characterized by the predominance of clear or slightly cloudy weather. Due to the cooling of air from the earth's surface in the cold season and at night, the formation of surface inversions and low stratus clouds (St) and fogs in the anticyclone is possible. In summer, moderate daytime convection with the formation of cumulus clouds is possible over land. Convection with the formation of cumulus clouds is also observed in the trade winds on the equatorial periphery of subtropical anticyclones. When the anticyclone stabilizes at low latitudes, powerful, high and warm subtropical anticyclones appear.
Stabilization of anticyclones also occurs in middle and polar latitudes. High inactive anticyclones that disrupt the general western transfer of middle latitudes are called blocking ones.
Synonyms: high pressure area, area high blood pressure, baric maximum.
Anticyclones reach a size of several thousand kilometers across. In the center of the anticyclone, the pressure is usually 1020-1030 mbar, but it can reach 1070-1080 mbar. Like cyclones, anticyclones move in the direction of the general transport of air in the troposphere, that is, from west to east, while deviating towards low latitudes. The average speed of movement of the anticyclone is about 30 km / h in the Northern Hemisphere and about 40 km / h in the Southern, but often the anticyclone takes a sedentary state for a long time.
Anticyclone signs:
- Clear or slightly cloudy weather
- No wind
- Lack of precipitation
- Stable nature of the weather (does not noticeably change over time, as long as there is an anticyclone)
In summer, the anticyclone brings hot, low-cloud weather, as a result of which forest fires are possible, which leads to the formation of strong smog. In winter, the anticyclone brings severe frosts, sometimes frosty fog is also possible.
Stages of development of anticyclones[ | ]
The initial stage of anticyclone development[ | ]
At the initial stage of development, the surface anticyclone is located under the rear part of the high-altitude baric trough, and the baric ridge at heights is shifted to the rear part relative to the surface baric center. A dense system of converging isohypsum is located above the surface center of the anticyclone in the middle troposphere. Wind speeds above the surface center of the anticyclone and somewhat to the right in the middle troposphere reach 70-80 km / h. The thermobaric field favors the further development of the anticyclone.
At such speeds in the area of convergence of air currents, a significant deviation of the wind from the gradient occurs (that is, the movement becomes unsteady). Descending air movements develop, the pressure increases, as a result of which the anticyclone increases.
On the surface weather map, the anticyclone is outlined by one isobar. The pressure difference between the center and the periphery of the anticyclone is 5-10 mb. An anticyclonic eddy is not detected at an altitude of 1–2 km. The area of dynamic pressure growth caused by the convergence of isohypsum extends to the entire space occupied by the surface anticyclone.
The surface center of the anticyclone is located practically under the thermal hollow. Isotherms average temperature the layers in front of the anticyclone near the ground center deviate from the isohypsum to the left, which corresponds to cold advection in the lower troposphere. A thermal ridge is located in the rear part relative to the surface center, and heat advection is observed.
The advective (thermal) increase in pressure at the earth's surface covers the forward part of the anticyclone, where cold advection is especially noticeable. In the rear of the anticyclone, where heat advection takes place, an advective pressure drop is observed. The zero advection line passing through the ridge divides the VFZ inlet region into two parts: the front, where cold advection takes place (advective pressure increase), and the rear, where heat advection takes place (advective pressure drop).
Thus, in total, the area of pressure growth covers the central and forward parts of the anticyclone. The greatest increase in pressure near the Earth's surface (where the regions of advective and dynamic pressure growth coincide) is noted in the front part of the anticyclone. In the rear, where dynamic growth is superimposed on the advective fall (heat advection), the total heat rise near the Earth's surface will be weakened. However, as long as the area of significant dynamic pressure growth occupies central part surface anticyclone, where the advective pressure change is equal to zero, there will be an increase in the arisen anticyclone.
So, as a result of the intensifying dynamic pressure increase in the front part of the VFZ inlet, the thermobaric field is deformed, leading to the formation of a high-altitude ridge. An independent anticyclone center is formed under this ridge near the Earth. At altitudes where an increase in temperature causes an increase in pressure, the area of pressure growth shifts to the rear of the anticyclone, towards the area of temperature increase.
Young anticyclone stage[ | ]
The thermobaric field of a young anticyclone in general outline corresponds to the structure of the previous stage: the baric ridge at altitudes relative to the surface center of the anticyclone is noticeably shifted to the rear part of the anticyclone, and a baric trough is located above its front part.
The center of the anticyclone near the Earth's surface is located under the front part of the baric ridge in the zone of the greatest concentration of isohypsum converging along the flow, the anticyclonic curvature of which decreases along the flow. With such an isohypsum structure, the conditions for further strengthening of the anticyclone are most favorable.
The convergence of the isohypsum above the anterior part of the anticyclone favors a dynamic increase in pressure. Cold advection is also observed here, which also favors the advective pressure increase.
In the rear part of the anticyclone, heat advection is observed. The anticyclone is a thermally asymmetric pressure formation. The thermal ridge lags slightly behind the baric ridge. The lines of zero advective and dynamic pressure changes at this stage begin to converge.
An increase in the anticyclone is noted near the Earth's surface - it has several closed isobars. The anticyclone quickly disappears with height. Usually, in the second stage of development, a closed center above the AT700 surface is not traced.
The stage of the young anticyclone ends with its transition to the stage of maximum development.
The stage of maximum development of the anticyclone[ | ]
The anticyclone is a powerful baric formation with high pressure in the surface center and a diverging system of surface winds. As it develops, the vortex structure spreads higher and higher. At heights above the surface center, there is still a dense system of converging isohypsum with strong winds and significant temperature gradients.
In the lower layers of the troposphere, the anticyclone is still located in the masses of cold air. However, as the anticyclone is filled with a homogeneous warm air a closed high pressure center appears at heights. The lines of zero advective and dynamic pressure changes pass through the central part of the anticyclone. This indicates that the dynamic increase in pressure in the center of the anticyclone has stopped, and the area of the greatest increase in pressure has moved to its periphery. From this moment, the weakening of the anticyclone begins.
Anticyclone destruction stage[ | ]
At the fourth stage of development, the anticyclone is a high pressure formation with a quasi-vertical axis. The closed centers of high pressure are traced at all levels of the troposphere, the coordinates of the high-altitude center practically coincide with the coordinates of the center near the Earth.
From the moment the anticyclone intensifies, the air temperature at the heights rises. In the anticyclone system, air is lowered, and, consequently, it is compressed and heated. In the rear part of the anticyclone, warm air (heat advection) enters its system. As a result of the continuing advection of heat and adiabatic heating of the air, the anticyclone is filled with homogeneous warm air, and the region of the greatest horizontal temperature contrasts moves to the periphery. A heat center is located above the ground center.
The anticyclone becomes a thermally symmetric pressure formation. Corresponding to the decrease in the horizontal gradients of the tropospheric thermobaric field, the advective and dynamic changes in pressure in the anticyclone region are significantly weakened.
Due to the divergence of air currents in the surface layer of the atmosphere, the pressure in the anticyclone system decreases, and it gradually collapses, which at the initial stage of destruction is more noticeable near the earth's surface.
Some features of the development of anticyclones[ | ]
The evolution of cyclones and anticyclones differs significantly from the point of view of deformation of the thermobaric field. The emergence and development of a cyclone is accompanied by the emergence and development of a thermal depression, an anticyclone - the emergence and development of a thermal ridge.
For the last stages of the development of baric formations, the combination of baric and thermal centers is characteristic, isohypsum and become almost parallel, a closed center can be traced at altitudes, moreover, the coordinates of the high-altitude and surface centers practically coincide (they say that the altitudinal axis of the baric formation is quasi-vertical). The deformation differences in the thermobaric field during the formation and development of the cyclone and anticyclone lead to the fact that the cyclone is gradually filled with cold air, the anticyclone - with warm air.
Not all emerging cyclones and anticyclones go through four stages of development. In each a separate case there may be some deviations from the classical picture of development.
Often, baric formations arising at the Earth's surface do not have conditions for further development and can disappear already at the beginning of their existence. On the other hand, there are situations when the old decaying pressure formation is revived and activated. This process is called the regeneration of baric formations.
But if different cyclones have a more definite similarity in the stages of development, then anticyclones, in comparison with cyclones, have much greater differences in development and shape. Anticyclones often appear as sluggish and passive systems that fill the space between much more active cyclonic systems. Sometimes an anticyclone can reach significant intensity, but such development is mostly associated with cyclonic development in neighboring areas.
Considering the structure and general behavior anticyclones, they can be divided into the following classes (according to Khromov S.P.).
- Intermediate anticyclones are rapidly moving areas of increased pressure between separate cyclones of the same series, arising at the same main front - for the most part they have the form of ridges without closed isobars, or with closed isobars in horizontal dimensions of the same order as moving cyclones. They develop inside cold air.
- Final anticyclones are those that conclude the development of a series of cyclones arising on the same main front. They also develop inside cold air, but usually have several closed isobars and can have significant horizontal dimensions. They tend to acquire a sedentary state as they develop.
- Stationary anticyclones of temperate latitudes, that is, long-term inactive anticyclones in the Arctic or polar air, the horizontal dimensions of which are sometimes comparable to a significant part of the continent. Usually these are winter anticyclones over continents and are mainly the result of the development of anticyclones of the second type (less often - the first).
- Subtropical anticyclones are long-term sedentary anticyclones observed over oceanic surfaces. These anticyclones are periodically intensified by intrusions from mid-latitudes of polar air with mobile final anticyclones. In the warm season, subtropical anticyclones are well expressed on average monthly maps only over the oceans (over the continents there are eroded areas reduced pressure). V cold season subtropical anticyclones tend to merge with cold anticyclones over continents.
- Arctic anticyclones are more or less stable areas of increased pressure in arctic basin... They are cold, so their vertical thickness is limited by the lower troposphere. In the upper part of the troposphere, they are replaced by a polar depression. Cooling from the underlying surface plays an important role in the emergence of Arctic anticyclones, that is, they are local anticyclones.
The height to which the anticyclone extends depends on temperature conditions in the troposphere.
Moving and final anticyclones have low temperatures in the lower atmosphere and temperature asymmetry in the overlying ones. They are classified as medium to low baric formations.
The height of stationary anticyclones in temperate latitudes increases as they stabilize, accompanied by a warming of the atmosphere. Most often these are high anticyclones, with closed contour lines in the upper troposphere. Winter anticyclones over a highly cooled land, for example, over Siberia, can be low or medium, since the lower troposphere is very cooled here.
Subtropical anticyclones are high - the troposphere in them is warm.
Arctic anticyclones, which are mainly thermal, are low.
Quite often, high warm and low-mobile anticyclones that develop in mid-latitudes for a long time (about a week or more) create macro-scale disturbances of zonal transport and deviate the trajectories of mobile cyclones and anticyclones from the west-east direction. Such anticyclones are called blocking anticyclones. Central cyclones together with blocking anticyclones determine the direction of the main currents of general circulation in the troposphere.
High and warm anticyclones and cold cyclones are, respectively, hot and cold centers in the troposphere. In the areas between these foci, new frontal zones, temperature contrasts increase and atmospheric vortices arise again, which go through the same life cycle.
Atmospheric phenomena have been the subject of research for centuries because of their significance and impact on all areas of life. Cyclone and anticyclone are no exceptions. Geography gives the concept of these weather phenomena at school. After such a short study, cyclones and anticyclones remain a mystery to many. and the fronts are key concepts that will help to depict the essence of these weather phenomena.
Air masses
It often happens that over many thousands of kilometers in the horizontal direction, air has very similar properties. This mass is called air.
Air masses are divided into cold, warm and local:
A cold mass is called if its temperature is lower than the temperature of the surface over which it is located;
Warm is an air mass whose temperature is higher than the temperature of the surface below it;
The temperature of the local air mass is no different from the surface under it.
Air masses are formed over different parts of the Earth, which leads to peculiarities in their properties. If the mass is formed over the Arctic, then, accordingly, it will be called Arctic. Of course, this air is very cold, it can bring thick fogs or light haze. The polar air considers the temperate latitudes to be its deposit. Its properties can change depending on what time of the year has come. In winter, polar masses are not much different from arctic ones, but in summer such air can bring very poor visibility.
Tropical masses that came from the tropics and subtropics have high fever and increased dustiness. They are the culprit behind the haze that engulfs objects when viewed from a distance. Tropical masses formed on the continental tropical belt, lead to dust whirlwinds, storms and tornadoes. Equatorial air is very similar to tropical air, but all these properties are more pronounced.
Fronts
If two air masses with different temperatures, meet, a new weather phenomenon is formed - a front, or interface.
By the nature of the movement, the fronts are divided into stationary and mobile.
Each existing front separates the air masses. For example, the main polar front is an imaginary intermediary between polar and tropical air, the main arctic front is between the arctic and polar, and so on.
If a warm air mass creeps onto a cold air mass, warm front... For travelers, entering such a front can portend either pouring rain or snow, which will significantly reduce visibility. When cold air wedges under warm air, the formation of a cold front is observed. Ships entering the cold front area suffer from squalls, showers and thunderstorms.
It so happens that the air masses do not collide, but catch up with one another. In such cases, an occlusion front is formed. If a cold mass plays the role of catch-up, then this phenomenon is called the front of cold occlusion, if, on the contrary, then the front of warm occlusion. These fronts carry heavy rainfall weather with strong gusts of wind.
Cyclones
To understand what an anticyclone is, you need to understand, This is an area in the atmosphere with a minimum index in the center. It is generated by two having different temperatures... Highly favorable conditions for their education are created in the fronts. In a cyclone, air moves from its edges, where the pressure is higher, to the center with In the center, the air seems to be thrown upwards, which makes it possible to form ascending currents.
By the way the air moves in the cyclone, it is easy to determine in which hemisphere it was formed. If its direction coincides with the movement of the clockwise, then this is definitely the Southern Hemisphere, if against it, it is
Cyclones provoke such weather conditions like the accumulation of cloud masses, heavy precipitation, wind and temperature drops.
Tropical cyclone
Cyclones formed in temperate latitudes are separated from cyclones, which owe their origin to the tropics. They have many names. These are hurricanes (West Indies), and typhoons (east of Asia), and just cyclones (Indian Ocean), and arcana (south Indian Ocean). These vortices range in size from 100 to 300 miles, and their centers range from 20 to 30 miles.
The wind here accelerates to 100 km / h, and this is typical for the entire vortex area, which fundamentally distinguishes them from cyclones formed in temperate latitudes.
Ripples in the water are a sure sign of such a cyclone approaching. And she goes to opposite side the wind blowing or the wind that blew shortly before.
Anticyclone
The area of increased pressure in the atmosphere with a maximum in the center is the anticyclone. The pressure at its edges is lower, which allows air to rush from the center to the periphery. The air in the center constantly descends and diverges to the edges of the anticyclone. This is how downdrafts are formed.
An anticyclone is also the opposite of a cyclone because in the Northern Hemisphere it follows the clockwise hand, in the Southern Hemisphere it goes against it.
After rereading all the above information, we can say with confidence what an anticyclone is.
An interesting property of mid-latitude anticyclones is that they seem to pursue cyclones. In this case, the sedentary state fully characterizes the anticyclone. The weather generated by this whirlwind is slightly cloudy and dry. There is practically no wind.
The second name of this phenomenon is the Siberian maximum. Its life span is about 5 months, namely the end of autumn (November) - the beginning of spring (March). This is not one anticyclone, but several, which very rarely give way to cyclones. The height of the winds reaches 3 km.
Due to the geographic environment (mountains of Asia), cold air cannot disperse, which leads to its further cooling, the temperature near the surface drops to 60 degrees below zero.
Speaking about what an anticyclone is, we can say with confidence that it is an atmospheric vortex huge size bringing clear weather without precipitation.
Cyclones and anticyclones. Similarities and differences
In order to understand better what an anticyclone and a cyclone are, you need to compare them. We have found out the definitions and main aspects of these phenomena. Remains open question about the difference between cyclones and anticyclones. The table will show this difference more clearly.
| № | Characteristic | Cyclone | Anticyclone |
| 1. | Dimensions (edit) | 300-5000 km in diameter | Can be up to 4000 km in diameter |
| 2. | Travel speed | 30 to 60 km / h | From 20 to 40 km / h (except for sedentary) |
| 3. | Places of origin | Everywhere except the equator | Over the ice sheet and in the tropics |
| 4. | Causes of occurrence | Due to the natural rotation of the Earth (Coliolis force), with a lack of air mass. | Due to the occurrence of a cyclone, with an excess of air mass. |
| 5. | Pressure | Low in the center, high at the edges. | It is elevated in the center, low at the edges. |
| 6. | Direction of rotation | In the Southern Hemisphere - clockwise, in the Northern - against it. | In the South - counterclockwise, in the North - clockwise. |
| 7. | Weather | Cloudy, strong wind, a lot of precipitation. | Clear or little cloudy, no wind or precipitation. |
Thus, we see the difference between cyclones and anticyclones. The table shows that these are not just opposites, the nature of their occurrence is completely different.
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