What is a cyclone and anticyclone? What is a cyclone? Action and characteristics of an atmospheric cyclone What is a cyclone and.

Atmospheric phenomena have been the subject of research for centuries due to their significance and influence on all areas of life. Cyclone and anticyclone are no exceptions. The concept of these weather phenomena is given by geography at school. Cyclones and anticyclones, after such a brief study, remain a mystery to many. and fronts are key concepts that help capture the essence of these weather phenomena.

Air masses

It often happens that over many thousands of kilometers in the horizontal direction the air has very similar properties. This mass is called air.

Air masses are divided into cold, warm and local:

A mass is called cold 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 underneath it;

The local air mass is no different in temperature from the surface underneath it.

Air masses form 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, such air is very cold and can bring thick fog or light haze. Polar air considers temperate latitudes to be its source. Its properties may change depending on what time of year it is. In winter, the polar masses are not much different from the Arctic, but in summer such air can bring very poor visibility.

Tropical masses coming from the tropics and subtropics have high temperature and increased dustiness. They are the culprits of the haze that envelops objects when viewed from a distance. Tropical masses formed on the continental part tropical zone, lead to dust devils, storms and tornadoes. Equatorial air is very similar to tropical air, but all these properties are more pronounced.

Fronts

If two air masses having different temperatures, meet, a new weather phenomenon is formed - a front, or interface.

Based on the nature of movement, fronts are divided into stationary and moving.

Each existing front separates air masses from each other. For example, the main polar front is an imaginary mediator between polar and tropical air, the main arctic front is between arctic and polar, and so on.

When a warm air mass moves over a cold one, a warm front occurs. For travelers, entering such a front can herald either heavy rain or snow, which will significantly reduce visibility. When cold air wedges under warm air, a cold front forms. Ships entering the area of a cold front suffer from squalls, showers and thunderstorms.

It happens that 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 a catching-up mass, then this phenomenon is called a front of cold occlusion; if, on the contrary, then a front of warm occlusion. These fronts bring showery weather with strong wind gusts.

Cyclones

To understand what an anticyclone is, you need to understand that it is an area in the atmosphere with a minimum indicator in the center. It is generated by two having different temperatures. Very favorable conditions for their education they are created at the fronts. In a cyclone, air moves from its edges, where the pressure is higher, to the center. In the center, the air seems to be thrown upward, which makes it possible to form upward flows.

By the way the air moves in a cyclone, you can easily determine in which hemisphere it formed. If its direction coincides with the clockwise movement, then this is definitely the Southern Hemisphere, but if it is counterclockwise, it is

Cyclones provoke weather phenomena such as the accumulation of cloud masses, heavy precipitation, wind and temperature changes.

tropical cyclone

From cyclones formed in temperate latitudes, separate cyclones that owe their origin to the tropics. They have many names. These are hurricanes (West Indies), and typhoons (East Asia), and simply cyclones (Indian Ocean), and arcana (South Indian Ocean). The sizes of such vortices range from 100 to 300 miles, and the diameter of the center is 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.

A sure sign of the approach of such a cyclone is ripples in the water. Moreover, it goes in the opposite direction to the blowing wind or the wind that blew shortly before.

Anticyclone

Region high blood pressure in an atmosphere with a maximum in the center - this is an 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 downward flows are formed.

An anticyclone is the opposite of a cyclone also because in the Northern Hemisphere it follows the clockwise direction, and in the Southern Hemisphere it goes counterclockwise.

After reading all the above information, we can say with confidence what an anticyclone is.

An interesting property of anticyclones in temperate latitudes is that they seem to chase cyclones. In this case, the sedentary state fully characterizes the anticyclone. The weather produced by this vortex is partly cloudy and dry. There is practically no wind.

The second name for this phenomenon is the Siberian Maximum. Its lifespan 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 geographical environment (the mountains of Asia), the cold air cannot disperse, which leads to its cooling even more, 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 of enormous size, bringing clear weather without precipitation.

Cyclones and anticyclones. Similarities and differences

In order to better understand what an anticyclone and a cyclone are, you need to compare them. We have found out the definitions and main aspects of these phenomena. The question remains of how cyclones and anticyclones differ. The table will show this difference more clearly.

№	Characteristic	Cyclone	Anticyclone
1.	Dimensions	300-5000 km in diameter	Can reach 4000 km in diameter
2.	Travel speed	From 30 to 60 km/h	From 20 to 40 km/h (except for sedentary vehicles)
3.	Places of occurrence	Everywhere except the equator	Above the ice sheet and in the tropics
4.	Causes	Due to the natural rotation of the Earth (Koliolis force), with a shortage of air mass.	Due to the occurrence of a cyclone, with excess air mass.
5.	Pressure	Low in the center, high at the edges.	High in the center, low at the edges.
6.	Direction of rotation	IN Southern Hemisphere- clockwise, in Northern - against it.	In the South - counterclockwise, in the North - clockwise.
7.	Weather	Cloudy, strong wind, lots of precipitation.	Clear or partly 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.

Scientists determined the natural phenomenon of a cyclone and anticyclone by changes in temperature, humidity and dust. Air masses have different properties depending on their location. In the snow-covered regions of the Arctic and Antarctica, the air is cold, clear and dry. Above the Equator it becomes hot and humid.

After long observations of the atmosphere scientists have given a clear definition of what a cyclone and anticyclone are. They came to the conclusion that the layers of the atmosphere consist of large air avalanches that move freely in space. In the layers of the atmosphere there is a constant movement of gusts of wind. The instability of the air allowed discoveries to be made.

What is a cyclone and anticyclone, definition and main points are covered in the scientific literature from different points of view. But all concepts describe the process of occurrence of atmospheric vortex disturbances.

The phenomena of a cyclone are atmospheric vortices of impressive size with reduced air pressure. They bring strong winds, hurricanes, thunderstorms and other unpleasant weather. Their occurrence occurs due to the rotation of the Earth. Cyclones northern hemisphere move air counterclockwise. In the southern hemisphere they move in reverse side. They have energetic power and bring strong gusty winds, heavy rainfall, storm clouds and lightning.
Anticyclone phenomena are characterized by increased pressure. In the northern hemisphere, anticyclones rotate clockwise, and in the southern hemisphere, vice versa. They bring clear stable weather, lack of wind and precipitation. In summer, warm, partly cloudy weather sets in for a while. In winter, days like these can be clear and cold.

IN different corners Earth's air masses are cold and warm due to the fact that the air movement of cyclones and anticyclones is constantly changing. Streams periodically collide and displace each other. In the layers of the atmosphere there is a constant movement of gusts of wind, from small in size to incredibly large in area. Cyclones and anticyclones reach a diameter of 3500-4000 km and a height of 20 km.

Interconnected phenomena

At first glance, these volumetric masses should have nothing in common. They are opposite in essence and have different origins. However, strong interaction with each other shows what the cyclone and anticyclone have in common:

If in one place there is low atmospheric pressure, then in another region the pressure increases
non-uniform heating of different parts of the surface and the rotation of the Earth is a common mechanism that causes the anticyclone and cyclone to move
both of them appear only in certain places. For example, the more extensive the surface is covered with ice, the greater the likelihood of excess air masses.

The most powerful anticyclone can be periodically observed over Antarctica, a relatively weak one over Greenland, and a moderate one over the Arctic.

Atmospheric circulation

Atmospheric vortices clearly characterize what anticyclones and cyclones are. In the upper layers of the Earth there is an area low pressure. In the center its pressure is always lower than at the periphery. It is in this place that powerful atmospheric air currents are formed, which move to the right and are called cyclones.

Anticyclones behave in a completely different way, exactly the opposite. They form in areas of high pressure. The highest performance is achieved in the center and veers to the left.

In the northern and southern hemispheres, the phenomena of cyclones and anticyclones create directly opposite effects. Some of them symbolize destruction and upheaval. Summer can bring heavy rain, strong winds, hurricanes and thunderstorms. In winter - snowfalls, storms, blizzards. Other phenomena bring low mobility and calmness. Changes in weather make it clear what a cyclone and anticyclone are.

Anticyclones are characterized by weak winds, minimum quantity precipitation or its complete absence. They make the days warm in summer, hot in some areas, sunny and frosty in winter.

What are cyclones and anticyclones, and why does the weather get cold on a clear day?

If the air on earth were always distributed evenly, then wind as such would not exist in nature. This is not observed in nature.

In areas with high pressure there is always an excess of air. Low blood pressure, on the contrary, is characterized by its disadvantage. Accordingly, air masses are not equally distributed on the surface of the earth. Clouds from areas of high air pressure are attracted by the cyclone. That's why it's always cloudy inside.

During an anticyclone, on the contrary, clouds are forced out. The sky becomes clear. In winter, the sun is low and the air does not warm up. There are no clouds, the heat doesn’t linger, it’s cold outside. Based on this feature, the presence of an anticyclone can be determined.

Stages of development

The phenomena of a cyclone and an anticyclone are closely related. In essence, this is a single long wave process. Cyclone and anticyclone go through several stages of development:

wavy stage (initial)
young air mass stage
achieving maximum development
air mass filling period

The initial stage of the cyclone passes within a day. It is characterized by a change in surface. The vortices are not visible at altitude. Warm air begins to move towards cold air. Stratus clouds appear in the sky.

In the second stage, warm and cold front connect at the center of the cyclone. An area of warm air mass forms between them. The rest is filled with cold air. Air masses also remain in this state throughout the day.

The third stage is accompanied by the lowest pressure in the center. It lasts from 12 to 24 hours. The pressure in the center of the cyclone increases sharply, and the wind speed becomes less. The warm air flow remains below. The cold air tries to overcome it. In a certain area, part of the layer is pushed back. As a result, a clash of masses occurs.

Then the air flow rapidly turns into a powerful whirlwind, the wind speed increases significantly and penetrates into the upper layers of the atmosphere. The cyclone captures the adjacent layers of air, drawing them in at a speed of up to 50 km/h. At distant fronts, greater speed is achieved than at the center. During this period, due to low pressure, a sharp change in weather occurs.

A developed cyclone enters the fourth stage and lasts for four days or more. The cloud vortex closes in the center and then moves to the periphery. At this stage, the speed decreases and heavy precipitation occurs.

The cyclone phenomenon is characterized by a lack of air. To replenish it, cold currents arrive. They push warm air upward. It cools down and the water condenses. Clouds appear from which heavy precipitation falls. This is what a cyclone is, and why the weather changes dramatically when it occurs.

Types of cyclones

The duration of the vortex ranges from several days to weeks. In area low blood pressure can last up to a year (for example, the Icelandic or Aleutian cyclone). In terms of their origin, the types of cyclones differ depending on the place of their origin:

eddies in temperate latitudes
tropical vortex
equatorial
arctic

Mass movement is constantly occurring in the Earth's atmosphere. In it, the vortices of the most different sizes. Warm and cold air currents collide at temperate latitudes and form areas of high and low pressure, which leads to the formation of vortices.

A tropical cyclone poses a great danger. It is formed where the ocean surface temperature is at least twenty-six degrees. Increased evaporation increases humidity. As a result, vertical air masses rush upward.

With a strong gust, new volumes of air are captured. They have already warmed up enough and become wet above the surface of the ocean. Rotating at great speed, air currents turn into hurricanes of destructive force. Of course, not every tropical cyclone causes destruction. When they move to land, they quickly calm down.

Movement speed in different stages

movement not exceeding 17 m/s is characterized as disturbance
at 17-20 m/s there is some depression
when the center reaches a speed of 38 m/s, a storm is approaching
when the forward motion of a cyclone exceeds 39 m/s, a hurricane is observed

The center of the cyclone is dominated by an area of calm weather. More than one is formed inside warm temperature, than in the rest of the air flow, there is less humidity. The tropical cyclone is the southernmost, characterized by its smaller size and higher wind speed.

For convenience, the phenomena of anticyclones and cyclones were first called numbers, letters, etc. Now they got women's and male names. When exchanging information, this does not create confusion and reduces the number of errors in forecasts. Each name contains specific data.

The phenomena of anticyclone and cyclone that form over the ocean differ in their properties from those that arose over the mainland. Marine air masses are warm in winter and cold in summer compared to continental air.

Tropical cyclones

Tropical cyclones mainly affect areas of the southeastern coast of Asia, the eastern part of the island of Madagascar, the Antilles, the Arabian Sea and the Bay of Bengal. More than seventy powerful cyclones are observed per year.

They are called differently, depending on the place of origin:

North and Central America - hurricane
West coast of Mexico Pacific Ocean– cordonazo
East Asia - typhoon
Philippines - Baruyo/Baguio
Australia - Willy Willy

The properties of temperate, tropical, equatorial and arctic air masses are easy to determine by name. Each tropical cyclone has its own name, for example, "Sarah", "Flora", "Nancy", etc.

Conclusion

Vertical-horizontal movements of air masses move in space. The atmosphere is an ocean of air, the winds are its current. Their boundless energy transports heat and moisture across all latitudes, from the oceans to the continents and back. Moisture and heat on Earth are redistributed due to the constant movement of air masses.

If there were no phenomenon of anticyclones and cyclones, then the temperature at the poles would be lower, and at the equator it would be hotter. The phenomenon of anticyclone and cyclone - powerful force, which can destroy, deposit and transport rock particles from one place to another.

At first, the wind powered the mills where they ground grain. On sailing ships he helped to overcome long distances of seas and oceans. Later, wind engines appeared, with the help of which people receive electricity.

Cyclone and anticyclone are a natural “mechanism” that transports air masses and influences weather changes. By delving deeper into the mysteries of what cyclones and anticyclones are, perhaps people will learn to use these natural phenomena with maximum benefit and benefit for humanity.

Marine site Russia no November 13, 2016 Created: November 13, 2016 Updated: November 13, 2016 Views: 31919

Information about weather and sea conditions necessary to decide on the choice of course or work at sea can be obtained in the form of facsimile transmissions of various maps.

This type of hydrometeorological information is the most informative.

It is characterized by great diversity, efficiency and visibility. Currently, regional hydrometeorological centers compile and broadcast a large number of a wide variety of cards. Below is a list of charts most commonly used for navigation purposes.

Surface weather analysis. The map is compiled based on surface meteorological observations within the main deadlines.

Surface weather forecast. Shows the expected weather in the specified area in 12, 24, 36 and 48 hours.

Short lead time surface forecast. The expected position of the pressure system (cyclones, anticyclones, fronts) in the surface layer for the next 3-5 days is given.

Wave field analysis. This map gives a description of the wave field in the area - the direction of wave propagation, their height and period.

Wave field forecast. Shows the forecasted wave field for 24 and 48 hours - the direction of the waves and the height of the prevailing waves.

Ice conditions map. The ice situation in the given area (concentration, ice edge, polynyas and other characteristics) and the position of icebergs are shown.

Nephelometric analysis maps (weather maps based on satellite data).

Surface analysis maps contain data about actual weather in the lower atmosphere. The pressure field on these maps is represented by isobars at sea level.
The main surface maps are for 00.00, 06.00, 12.00 and 18.00 hours Greenwich Mean Time. Forecast maps are maps of the expected weather conditions (l2, 24, 36, 48, 72 hours). On surface forecast maps, the expected positions of the centers of cyclones and anticyclones, frontal sections, and pressure fields are indicated.

When reading facsimile hydrometeorological maps, the navigator receives initial information from the map header.

The map header contains the following information:

card type;

the geographic area covered by the map;

hydrometeorological station call signs;

date and time of publication;

additional information.

The type and region of the map is characterized by the first four symbols, with the first two characterizing the type, and the next two characterizing the map region. For example:

ASAS – surface analysis (AS – analysis surface) for the Asian part (AS – Asia);

FWPN – wave forecast (FW – forecast wave) for the northern part of the Pacific Ocean (PN – Pacific North). Common abbreviations are listed below:

1. Maps of hydrometeorological situation analysis.

AS – surface analysis (Surface Analysis);

AU – Upper Analysis for various heights(pressure);

AW – wave/wind analysis;

2. Prognostic cards (for 12, 24, 48 and 72 hours).

FS – surface forecast (Surface Forecast)

FU – altitude forecast (Upper Forecast) for various heights (pressures).

FW – wind/wave forecast (Wave/Wind Forecast)

3. Special cards.

ST—ice forecast (Sea Ice Condition);

WT – tropical cyclone forecast (Tropical Cyclone Forecast);

CO – Sea Surface Water Temperature map;

SO – map of surface currents (Sea Surface Current).

The following abbreviations are commonly used to indicate the area covered by the map:

AS – Asia;

AE – Southeast Asia

PN – Pacific North;

JP – Japan;

WX - equatorial belt(Equator zone), etc.

Four alphabetic characters may be accompanied by 1-2 numeric characters specifying the type of map, for example FSAS24 - surface analysis for 24 hours or AUAS70 - above-ground analysis for 700 hPa pressure.

The type and area of the map are followed by the call sign of the radio station broadcasting the map (for example, JMH - Japan Meteorological and Hydrographic Agency). The second line of the title indicates the date and time the map was compiled.
Date and time are in Greenwich Mean Time or UTC. To denote the given time, the abbreviations Z (ZULU) and UTC (Universal Coordinated Time) are used, respectively, for example, 240600Z JUN 2007 - June 24, 2007, 06.00 GMT.

The third and fourth lines of the header decipher the card type and give Additional Information(Fig. 18.15).

Pressure relief on facsimile maps is represented by isobars - lines of constant pressure. On Japanese maps weather isobars are drawn through 4 hectopascals for pressures divisible by 4 (for example, 988, 992, 996 hPa).
Every fifth isobar, i.e. multiple of 20 hPa, drawn with a thick line (980, 1000, 1020 hPa). Such isobars are usually (but not always) labeled with pressure. If necessary, intermediate isobars are also drawn through 2 hectopascals. Such isobars are drawn with a dotted line.

Pressure formations on weather maps of Japan are represented by cyclones and anticyclones. Cyclones are designated by the letter L (Low), anticyclones by the letter H (High).
The center of baric formation is indicated by the sign “×”. The pressure in the center is indicated next to it. An arrow near the pressure formation indicates the direction and speed of its movement.

Rice. 18.15. Surface weather analysis map for the Asian area

There are the following ways to indicate the speed of movement of pressure formations:

ALMOST STNR – almost stationary (almost stationary) – pressure formation speed less than 5 knots;

SLW – slow (slowly) – pressure formation speed from 5 to 10 knots;

10 kT – speed of pressure formation in knots with an accuracy of 5 knots;

Text comments are given for the deepest cyclones, which give the characteristics of the cyclone, the pressure in the center, the coordinates of the center, the direction and speed of movement, maximum speed winds, as well as the zone of winds with speeds exceeding 30 and 50 knots.

An example of a comment on a cyclone:

DEVELOPING LOW 992 hPa 56.2N 142.6E NNE 06 KT MAX WINDS 55 KT NEAR CENTER OVER 50 KT WITHIN 360 NM OVER 30 KT WITHIN 800 NM SE-SEMICIRCULAR 550 NM ELSEWHERE,

DEVELOPING LOW – developing cyclone. There may also be DEVELOPED LOW - a developed cyclone;

pressure in the center of the cyclone - 992 hPa;

coordinates of the cyclone center: latitude - 56.2° N, longitude - 142.6° E;

the cyclone is moving at NNE at 6 knots;

the maximum wind speed near the center of the cyclone is 55 knots.

A tropical cyclone (TC) occupies a special place on weather maps. The World Meteorological Organization defines a TC as “a cyclone of tropical origin of small diameter (several hundred kilometers) with a minimum surface pressure, sometimes less than 900 hPa, very strong winds and heavy rain; sometimes accompanied by thunderstorms. It is usually distinguished by a central region, or “eye” hurricane", with a diameter of about several tens of kilometers, weak winds and more or less insignificant cloudiness.

There are no frontal systems in tropical cyclones. In the Atlantic, TCs are called hurricanes, in the Pacific - typhoons, in the north of the Indian Ocean - cyclones, in the south of the Indian Ocean - lassoes, off the coast of Australia - willy-willies.

The duration of existence of a shopping center is from 3 to 20 days. Atmospheric pressure in the TC drops from the periphery to the center and in the center is 950-970 mb. The average wind speed at a distance of 150-200 miles from the center is 10-15 m/s, at 100-150 miles - 15-22 m/s, at 50-100 miles - 22-25 m/s, and at 30-35 miles from the center the wind speed reaches 30 m/s.

An important sign of an approaching TC at distances up to 1,500 miles from the center of the cyclone can be the appearance of cirrus clouds in the form of thin transparent stripes, feathers or flakes that are clearly visible at sunrise and sunset. When these clouds appear to converge at one point over the horizon, the center of the TC can be considered to be located about 500 miles from the ship in the direction of the convergence of the clouds.

A tropical cyclone goes through 4 main stages in its development:

TD – tropical depression (Tropical Depression) – an area of low pressure (cyclone) with a wind speed of up to 17 m/s (33 knots, 7 points on the Beaufort scale) with a pronounced center;

TS – tropical storm (Tropical Storm) – tropical cyclone with a wind speed of 17-23 m/s (34-47 knots, 8-9 points on the Beaufort scale);

STS – strong (severe) tropical storm (Severe Tropical Storm) – a tropical cyclone with a wind speed of 24-32 m/s (48-63 knots, 10-11 points on the Beaufort scale);

T – typhoon (Typhoon) – a tropical cyclone with a wind speed of more than 32.7 m/s (64 knots, 12 points on the Beaufort scale).

The direction and speed of movement of a tropical cyclone is indicated in the form of a probable sector of movement and circles of probable position after 12 and 24 hours. Beginning with the TS (tropical storm) stage, weather maps provide a text commentary on the tropical cyclone, and, beginning with the STS (severe tropical storm) stage, the tropical cyclone is given a number and name.

An example of a tropical cyclone comment:

T 0408 TINGTING (0408) 942 hPa

26.2N 142.6E PSN GOOD NORTH 13 KT

MAX WINDS 75 KT NEAR CENTER EXPECTED MAX WINDS 85

KT NEAR CENTER FOR NEXT 24 HOUR OVER 50 KT WITHIN 80

NM OVER 30 KT WITHIN 180 NM NE-SEMICIRCULAR

270 NM ELSEWHERE,

T (typhoon) - stage of development of a tropical cyclone;

0408 - national number;

typhoon name - TINGTING;

(0408) - international number (eighth cyclone of 2004);

pressure in the center 942 hPa;

coordinates of the cyclone center 56.2° N 142.6° E. The coordinates are determined with an accuracy of 30 nautical miles(PSN GOOD).

To indicate the accuracy of determining the coordinates of the cyclone center, the following notations are used:

PSN GOOD – accuracy up to 30 nautical miles;

PSN FAIR – accuracy 30-60 nautical miles;

PSN POOR – accuracy below 60 nautical miles;

moving at NORTH at 13 knots;

maximum wind speed of 75 knots near the center;

expected maximum wind speed of 85 knots for the next 24 hours.

Weather maps also indicate navigation hazards in the form of hydrometeorological warnings. Types of hydrometeorological warnings:

[W] – warning about wind (Warning) with a speed of up to 17 m/s (33 knots, 7 points on the Beaufort scale);

– warning of strong wind (Gale Warning) with a speed of 17-23 m/s (34-47 knots, 8-9 points on the Beaufort scale);

– warning about storm wind (Storm Warning) with a speed of 24-32 m/s (48-63 knots, 10-11 points on the Beaufort scale);

– warning about hurricane wind(Typhoon Warning) at a speed of more than 32 m/s (more than 63 knots, 12 points on the Beaufort scale).

FOG [W] - FOG Warning with visibility less than ½ mile. The boundaries of the warning area are indicated by a wavy line. If the warning area is small, its boundaries are not indicated. In this case, the area is considered to occupy a rectangle described around the warning inscription.

Hydrometeorological data is applied to weather maps according to a certain scheme, with symbols and numbers, around a circle indicating the location of a hydrometeorological station or ship.

Example of information from a hydrometeorological station on a weather map:

In the center there is a circle depicting a hydrometeorological station. Circle shading shows total clouds (N):

dd - wind direction, indicated by an arrow going to the center of the station circle from the side where the wind is blowing.

ff - wind speed, depicted as an arrow feather with the following symbols:

In the absence of wind (calm), the station symbol is depicted as a double circle.

VV is the horizontal visibility indicated by the code number according to the following table:

PPP – atmospheric pressure in tenths of hectopascal. Numbers of thousands and hundreds of hectopascals are omitted. For example, a pressure of 987.4 hPa is plotted on the map as 874, and 1018.7 hPa as 187. The sign “xxx” indicates that the pressure was not measured.

TT – air temperature in degrees. The sign “xx” indicates that the temperature was not measured.

Nh is the number of low-level clouds (CL), and in their absence, the number of middle-level clouds (CM), in points.

CL, CM, CH - the shape of the clouds of the lower (Low), middle (Middle) and upper (High) tiers, respectively.

pp is the value of the pressure trend over the last 3 hours, expressed in tenths of hectopascal, the sign “+” or “–” before pp means, respectively, an increase or decrease in pressure over the last 3 hours.

a - characteristic of the pressure trend over the last 3 hours, indicated by symbols characterizing the course of pressure changes.

w - weather between observation periods.

ww - weather at the time of observation.

Some time ago, scientists could not even think that about two hundred cyclones and about fifty anticyclones form on the surface of the planet, because many of them remained invisible due to the lack of weather stations in the areas where they arise. But now there are satellites that record the changes that occur. What are cyclones and anticyclones, and how do they arise?

First, what is a cyclone

A cyclone is a huge atmospheric vortex with low air pressure. In it, air masses always mix counterclockwise in the north and clockwise in the south.

They say that a cyclone is a phenomenon that is observed on different planets, including the Earth. It occurs due to rotation celestial body. This phenomenon is extremely powerful and brings with it strong winds, precipitation, thunderstorms and other phenomena.

Anticyclone

In nature there is such a thing as an anticyclone. It is not difficult to guess that this is the opposite phenomenon of a cyclone. It is characterized by the movement of air masses counterclockwise in the southern hemisphere and clockwise in the northern hemisphere.

Anticyclones can stabilize the weather. After them, calm, quiet weather sets in over the territory: it is hot in summer and frosty in winter.

Cyclones and anticyclones

So what is a cyclone and an anticyclone? These are two phenomena that occur in the upper atmosphere and carry different weather. The only thing these phenomena have in common is that they occur over certain territories. For example, anticyclones most often occur over ice fields. And the larger the ice area, the stronger the anticyclone.

For many centuries, scientists have tried to determine what a cyclone is, what its significance is and what it affects. The key concepts of this atmospheric phenomenon air masses and fronts are considered.

Air masses

Over many thousands of kilometers, horizontal air masses have the same properties. They are divided into cold, local and warm:

Cold ones have a lower temperature than the surface over which they are located.
In warm ones it is greater than on the surface where they are located.
Local mass is air whose temperature is no different from the territory that is located underneath it.

Air masses form over very different parts of the Earth, which determines their characteristics and various properties. The area over which air masses form gives them their name.

For example, if they appear over the Arctic, they are given the name Arctic. This air is cold, with fogs and haze. Tropical air masses bring heat and lead to the formation of vortices, tornadoes, and storms.

Cyclones

An atmospheric cyclone is an area of low pressure. It occurs due to two air flows with different temperatures. The center of the cyclone has minimal atmospheric indicators: the pressure in its central part is lower, and at the edges it is high. It seems that air masses are thrown upward, thereby forming upward air currents.

By the direction of movement of air masses, scientists can easily determine in which hemisphere it was formed. If its movement coincides with the clock hand, then it originated in the Southern Hemisphere, and if the air moves against it, the cyclone came from the Northern Hemisphere.

In the zone of action of a cyclone, phenomena such as accumulations of cloud masses, sudden temperature changes, precipitation, thunderstorms, and whirlwinds can be observed.

Cyclone born over the tropics

Tropical cyclones are different from those that occur over other areas. These types of phenomena go by a variety of names: hurricanes, typhoons, arcana. Tropical eddies are usually large - up to three hundred miles or more. They are capable of driving winds at speeds of more than 100 km/h.

A distinctive feature of this atmospheric phenomenon from others is that the wind accelerates throughout the entire territory of the cyclone, and not only in certain zones, as is the case with cyclones that occur in the temperate zone. Main sign The approach of a tropical cyclone is the appearance of ripples in the water. Moreover, it goes in the opposite direction from the wind.

In the 70s of the last century, tropical cyclone Bhola hit Bangladesh, which was assigned the third category out of the existing five. It had a low wind speed, but the accompanying rain caused the Ganges River to overflow its banks, which flooded all the islands, washing away all the settlements. As a result of this disaster, more than 500 thousand people died.

Cyclone scales

Any cyclone action is rated on the hurricane scale. It indicates the category, wind speed and storm tide:

The first category is considered the easiest. With it, a wind of 34-44 m/s is observed. Storm tide does not exceed two meters.
Second category. It is characterized by winds of 50-58 m/s and a storm tide of up to 3 m.
Third category. The wind force can reach 60 meters per second, and the storm tide can reach no more than 4 m.
Fourth category. Wind - up to 70 meters per second, storm tide - about 5.5 m.
The fifth category is considered the strongest. It includes all cyclones with a wind force of 70 meters per second and a storm tide of more than 5.5 meters.

One of the most famous category 5 tropical hurricanes is Katrina, which killed almost 2,000 people. Hurricanes “Wilma”, “Rita”, “Ivan” also received category five. During the passage of the latter through America, more than one hundred and seventeen tornadoes formed.

Stages of cyclone formation

The characteristics of the cyclone are determined as it passes through the territory. At the same time, its stage of formation is specified. There are four in total:

First stage. It is characterized by the beginning of the formation of a vortex from air currents. At this stage, deepening occurs: this process usually takes about a week.
Young cyclone. A tropical cyclone at a young stage can go into different directions or move in the form of small air masses over short distances. In the central part there is a drop in pressure, and a dense ring with a radius of about 50 km begins to form around the center.
Maturity stage. It is characterized by a cessation of pressure drop. At this stage, the wind speed reaches its maximum and stops increasing. The radius of storm winds is located on the right side of the cyclone. This stage can last from several hours to several days.
Attenuation. When a cyclone makes landfall, the decay stage begins. During this period, a hurricane can go in two directions at once, or it can gradually fade, turning into lighter tropical whirlwinds.

Snake rings

Cyclones (from the Greek "snake ring") are vortices gigantic size, the diameter of which can reach thousands of kilometers. They usually form in places where air from the equator collides with oncoming cold currents. The boundary formed between them is called the atmospheric front.

During a collision, warm air prevents cold air from passing through. In these areas, pushing back occurs, and the air mass is forced to rise higher. As a result of such collisions between masses, pressure increases: part of the warm air is forced to deviate to the side, yielding to the pressure of cold air. This is how the rotation of air masses occurs.

The resulting vortices begin to capture new air masses, and they begin to move. Moreover, the movement of the cyclone in its central part is less than along the periphery. In those zones where the vortex moves sharply, strong jumps in atmospheric pressure are observed. In the very center of the funnel, a lack of air is formed, and in order to somehow compensate for it, cold masses enter the central part. They begin to displace warm air upward, where it cools, and the water droplets in it condense and form clouds, from which precipitation then falls.

The vortices can live for several days or several weeks. In some regions, cyclones almost a year old have been recorded. This phenomenon is typical for areas with low pressure.

Types of cyclones

There are the most different types vortexes, but not every one of them brings destruction. For example, where cyclones are weak but very windy, the following phenomena may be observed:

Outrage. During this phenomenon, the wind speed does not exceed seventeen meters per second.
Storm. In the center of the cyclone, the speed of movement is up to 35 m/s.
Depression. With this type, the speed of the cyclone is from seventeen to twenty meters per second.
Hurricane. With this option, the cyclone speed exceeds 39 m/s.

Scientists about cyclones

Every year, scientists around the world record the intensification of tropical cyclones. They become stronger, more dangerous, their activity increases. Because of this, they are found not only in tropical latitudes, but also in European countries, and at an atypical time for them. Most often this phenomenon is observed in late summer and early autumn. Cyclones have not yet been observed in the spring.

One of the most powerful whirlwinds that swept over European countries was Hurricane Lothar in 1999. He was very powerful. Meteorologists could not detect it due to sensor failure. This hurricane caused hundreds of deaths and caused serious damage to forests.

Record cyclones

Hurricane Camila occurred in 1969. In two weeks he reached from Africa to America and reached a wind force of 180 km/h. After passing through Cuba, its strength weakened by twenty kilometers, and scientists believed that by the time it reached America, it would weaken even more. But they were wrong. After crossing the Gulf of Mexico, the hurricane gained strength again. “Camila” was assigned the fifth category. More than 300 thousand people were missing and thousands were injured. Here are a few more sad record holders:

The Bhola cyclone of 1970 was the record for the number of victims, which claimed more than 500 thousand lives. The potential number of victims could reach a million.
In second place is Hurricane Nina, which killed more than one hundred thousand people in China in 1975.
In 1982, Hurricane Paul raged in Central America, killing nearly a thousand people.
In 1991, Cyclone Thelma hit the Philippines, killing several thousand people.
The worst was Hurricane Katrina in 2005, which claimed almost two thousand lives and caused almost one hundred billion dollars in damage.

Hurricane Camila is the only one that made landfall, retaining all its power. Wind gusts reached 94 meters per second. Another record holder for wind strength was registered on the island of Guam. The typhoon had winds of 105 meters per second.

Among all the recorded vortices, “Type” had the largest diameter, stretching over more than 2100 kilometers. The smallest typhoon is Marco, which has a wind diameter of only 37 kilometers.

If we judge by the lifespan of a cyclone, John raged the longest in 1994. It lasted 31 days. He also holds the record for the longest distance traveled (13,000 kilometers).

Just recently, before the invention of satellites, meteorologists could not even imagine that every year earth's atmosphere About 150 cyclones and about 60 anticyclones arise.

Now scientists know not only their quantity, but also the process of formation, as well as the impact on Earth. What is this natural phenomena? How do they arise and what role do they play in the earth's climate?

What is a cyclone?

In the troposphere (lower atmospheric layer), atmospheric vortices constantly appear and disappear. Many of them are quite small, but some are enormous in size, reaching several thousand kilometers across.

If such a vortex moves counterclockwise in the northern hemisphere or clockwise in the southern hemisphere, and there is an area of low pressure inside, then it is called a cyclone. It has a colossal supply of energy and leads to negative weather events such as thunderstorms, strong winds, squalls.

Depending on where they form, cyclones are classified as tropical or extratropical. The first ones appear in tropical latitudes and are small in size (several hundred kilometers in diameter). At their center there is usually an area with a diameter of 20–25 km with sunny weather, and storms and winds rage at the edges.

Extratropical cyclones, formed in polar and temperate latitudes, reach gigantic sizes and simultaneously cover large areas of the earth's surface. They are called differently in different areas: in America - typhoon, in Asia - typhoon, and in Australia - willy-willy. Each powerful cyclone receives given name, for example Katrina, Sandy, Nancy.

How does a cyclone occur?

The reason for the occurrence of cyclones lies in rotation globe and is associated with the Coriolis force, according to which, when moving counterclockwise, the vortices are deflected to the left, and when moving clockwise they go to the right. Cyclones form when warm equatorial air masses meet dry Arctic currents. When they collide, a barrier appears between them - atmospheric front.

In an attempt to overcome this boundary, cold flows push aside some of the warm layers, and they, in turn, collide with the cold masses following them and begin to rotate along an ellipsoidal trajectory. Gradually they capture the surrounding air layers, draw them into their movement and move along the surface of the Earth at speeds of up to 50 kilometers per hour.

What is an anticyclone?

Anticyclones, as the name implies, are the complete opposite of cyclones and bring certain territories good weather.

In their inner part there is an area of high pressure, and the speed of movement varies from 30 to 40 kilometers per hour depending on the hemisphere. Often, anticyclones hover in a stationary state, maintaining low clouds, calm and lack of precipitation in a particular region for a long time.

IN summer time anticyclones lead to heat, in winter, on the contrary, to severe frosts. They occur in subpolar or subtropical latitudes, and when formed over thick ice cover (for example, in Antarctica) they become more pronounced.

Anticyclones are characterized by sharp temperature changes throughout the day, which explains the lack of precipitation, which, as a rule, affects the temperature and makes the difference in degrees not so noticeable. Sometimes while they are moving over earth's surface fogs or stratus clouds appear.

How do anticyclones develop?

Anticyclones have a more complex structure than cyclones. In the northern hemisphere they move clockwise, in the southern hemisphere they move counterclockwise. The formation of anticyclones is caused by the invasion of cold air currents into warmer ones.

As a result, pressure increases in the collision area and a so-called high-altitude ridge is formed, under which a vortex center begins to form. As they grow, anticyclones reach sizes up to several thousand kilometers in diameter and move from west to east, deviating towards lower latitudes.