What is it and what is the difference between a cyclone and an anticyclone. Symbols on domestic facsimile maps Cyclone is indicated by the letter

As a child, listening to the weather forecast, I was very frightened by phrases like “a powerful cyclone". The cyclone in my imagination was drawn to me by some huge and terrible insect. Apparently, somewhere I heard about cyclops, and these two similar-sounding words intertwined and created a fairy-tale monster in the children's minds, which every now and then “approaches” some unfortunate country.

Of course, as I got older, I realized that cyclones and anticyclones are somehow related to the weather, but how exactly - it remained a mystery to me for a long time.

Cyclone and anticyclone: ​​what is it

Cyclones and anticyclones are usually taught in geography lessons. But for some reason, as a result of the explanations of the teacher and the textbook, there is no clarity. Maybe I can do better?

So and a cyclone and an anticyclone are huge multi-kilometer air vortices in which the air moves in a circle. They behave completely differently. In a cyclone, the air rotates outward from the center, counterclockwise in the northern hemisphere, and clockwise in the southern hemisphere (it is easy to assume that everything happens exactly the opposite in an anticyclone). Atmospheric pressure in a cyclone is always low(who can guess how things are with the pressure in the anticyclone?)

Diagram of a cyclone and an anticyclone

Evil cyclones always bring with them strong winds, squalls, rains, thunderstorms and other weather problems. And here with the advent of the anticyclone, good calm and cloudy weather sets in.

How do cyclones and anticyclones form?

So, you understand that cyclones and anticyclones are air turbulences. But how and why do they appear? To answer this question, you will have to understand the concept of " atmospheric front.

Imagine two neighboring regions, in one of which warm weather has been established, and in the other - cold. Places where cold and warm air masses meet are called atmospheric fronts..

When meeting, warm and cold air masses do not mix, but seem to fight each other, press “wall against wall”, twisting into a spiral as a result. This is how air (or atmospheric) vortices are obtained.

Tropical cyclones

Both cyclones and anticyclones usually occur in certain places on the globe.. So, anticyclones are often born over the Arctic and Antarctica. And here cyclones like to form in the tropics. For tropical phenomena, due to their particular destructiveness, they even came up with special names:

• in America - a hurricane;
• in East Asia - a typhoon;
• in Mexico - cordonaso;
• in the Philippines - baguio;
• in Australia - willy-willy.

Atmospheric phenomena have been an object of study for centuries because of their significance and influence on all spheres of life. Cyclones and anticyclones are no exception. The concept of these weather phenomena is given at school by geography. Cyclones and anticyclones, after such a brief study, remain a mystery to many. and fronts are key concepts that will help capture the essence of these weather events.

air masses

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

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 - this is such an air mass, the temperature of which is higher than the temperature of the surface that is under it;

The local air mass does not differ in temperature from the surface below 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, it can bring thick fogs or light haze. Polar air considers temperate latitudes to be its deposit. Its properties may vary depending on what time of the year it is. In winter, the polar masses are not much different from the Arctic ones, but in summer such air can bring very poor visibility.

Tropical masses that came from the tropics and subtropics have a high temperature and increased dust content. They are responsible for the haze that covers objects when viewed from a distance. Tropical masses formed on the continental part of the 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.

According to the nature of the movement, the fronts are divided into stationary and mobile.

Each existing front divides the air masses among themselves. For example, the main polar front is an imaginary mediator between polar and tropical air, the main arctic front is between arctic and polar air, and so on.

When a warm air mass moves over a cold air mass, a warm front occurs. For travelers, the entrance to such a front may herald either heavy rain or snow, which will significantly reduce visibility. When cold air is wedged under warm air, a cold front is formed. Ships entering the cold front suffer from squalls, downpours 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 such a phenomenon is called a cold occlusion front, if vice versa, then a warm occlusion front. These fronts bring torrential 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 indicator in the center. It is generated by two having different temperatures. Very favorable conditions for their formation are created in 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 upwards, which makes it possible to form ascending flows.

By the way the air moves in a cyclone, it is easy to determine in which hemisphere it was formed. If its direction coincides with the movement of the hour hand, then this is definitely the Southern Hemisphere, if it is against it, this is

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

tropical cyclone

From cyclones formed in temperate latitudes, cyclones are separated, which owe their origin to the tropics. They have many names. These are hurricanes (West Indies), and typhoons (east of Asia), and simply cyclones (Indian Ocean), and arcana (south of the Indian Ocean). The dimensions 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 radically distinguishes them from cyclones formed in temperate latitudes.

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

Anticyclone

The area of ​​high 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 located in the center constantly descends and diverges towards 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 hour hand, in the Southern Hemisphere it goes against it.

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

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

The second name of this phenomenon is the Siberian maximum. Its life expectancy 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 (mountains of Asia) cold air cannot disperse, which leads to even more cooling, the temperature near the surface drops to 60 degrees below zero.

Speaking about what an anticyclone is, we can say with confidence that this is an atmospheric vortex of enormous 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 clarified the definitions and main aspects of these phenomena. The question of how cyclones and anticyclones differ remains open. The table will show this difference more clearly.

Thus, we see how cyclones and anticyclones differ. The table shows that these are not just opposites, the nature of their occurrence is completely different.

On domestic synoptic maps of the low pressure zone - cyclones (Low Pressure Systems, Cyclones)- are denoted by the letter H (low). On foreign maps, the letter L is used (Low, low pressure).

In the northern hemisphere, due to the Coriolis force, the air masses deviate to the right in the course of their movement and twist around the area of ​​high pressure clockwise, and around the area of ​​low pressure - counterclockwise:

In the southern hemisphere, the opposite is true.

It is cyclones that bring us the main troubles - giant air vortices with warm and cold fronts. At the time of inception, a mid-latitude cyclone is about 500 nautical miles in diameter.

Let's look at how a typical cyclone of temperate latitudes arises, develops and ceases to exist in the northern hemisphere.

1. As we already know, in the region of 60 ° latitude, warm air masses that came from the subtropics and cold polar air coexist side by side. Imagine that on the boundary of these masses there is an oncoming local movement.

2. The warm wind is directed to the north, the cold wind is directed to the south, from the area of ​​contact of these winds the air is blown out in different directions and an area of ​​low pressure is formed.

3. Due to the action of the Coriolis force, the air masses begin to spin counterclockwise around the formed area of ​​low pressure and mix. The fronts of warm and cold air begin to rotate.

4. The front is the boundary zone between the masses of warm and cold air. If a mass of warm air moves over a mass of cold air, it is a warm front (Warm Front), if vice versa, it is cold (Cold Front). On the synoptic map, a warm front is indicated by red semicircles, a cold front is indicated by blue triangles in the direction of travel. Since a warm front is decelerated by denser and heavier cold air, a cold front always moves faster than a warm one. The warm air zone between the warm and cold fronts is called the Warm Sector. In the end, the cold front catches up with the warm front and an occlusion front is formed at the place of their contact.

5. The cold front continues to catch up with the warm front, there is an active mixing of air masses on the occluded front, the warm sector goes into the upper layers of the atmosphere, the pressure in the cyclone core rises. The cyclone gradually ceases to exist.

We looked at the process of cyclone formation from above, let's see what a cyclone looks like in the middle phase of its development in a cross section, what are the signs of an approaching cyclone and the characteristics of a cyclone as a whole:

As a whole formation, at the height of its development, the cyclone moves in the direction of the wind blowing in the warm sector, i.e. moves in the direction of the isobars of the warm sector.

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

After long observations of the atmosphere, scientists gave 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 volatility 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 heavy winds, hurricanes, thunderstorms and other unpleasant weather. They are created due to the rotation of the Earth. Northern hemisphere cyclones move air counterclockwise. In the southern hemisphere, they move in the opposite direction. They have energy power and bring strong gusty winds, heavy rainfall, thunderclouds and lightning.
• Anticyclone phenomena are characterized by increased pressure. In the northern hemisphere, anticyclones rotate clockwise, and vice versa in the southern hemisphere. They bring clear stable weather, lack of winds and precipitation. In summer, warm, slightly cloudy weather sets in for a while. In winter, these days are clear and cold.

In different parts of the Earth, air masses are cold and warm due to the fact that the movement of air of a cyclone and anticyclone is constantly changing. The flows 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 huge in area. Cyclones and anticyclones reach a diameter of 3500-4000 km and a height of 20 km.

Related Phenomena

At first glance, these volumetric masses should have nothing in common. They are opposite in essence, have a different nature of occurrence. However, strong interactions with each other show what a cyclone and an anticyclone have in common:

• if there is a decrease in atmospheric pressure in one place, 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 makes the anticyclone and cyclone move
• both of them appear only in certain places. For example, the larger the surface covered with ice, the greater the likelihood of excess air masses.

Over Antarctica, one can periodically observe the most powerful anticyclone, over Greenland - a relatively weak one, over the Arctic - of medium power.

Atmospheric circulation

Atmospheric vortices clearly characterize what anticyclones and cyclones are. There is an area of ​​low pressure in the upper layers of the Earth. 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 side and are called cyclones.

Quite differently, exactly the opposite, anticyclones behave. They form in areas of high pressure. The highest rates are reached in the center and deviate 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. In summer, there can be heavy rains, strong winds, hurricanes and thunderstorms. In winter - snowfalls, storms, blizzards. Other phenomena bring little mobility and calmness. A change in the weather makes it clear what a cyclone and anticyclone are.

Anticyclones are characterized by weak winds, minimal or no precipitation. They make the days warm in summer, hot in some areas, sunny and frosty in winter.

What is a cyclone and anticyclone, and why is the weather cold on a clear day?

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

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

With an anticyclone, on the contrary, the clouds are forced out. The sky becomes clear. In winter, the sun is low, the air does not warm up. There are no clouds, the heat does not linger, it is cold outside. By this sign, the presence of an anticyclone can be determined.

Stages of development

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

1. undulating stage (initial)
2. young air mass stage
3. achieving maximum development
4. air mass filling period

The initial stage of the cyclone passes within a day. It is characterized by a change in the surface. Vortices are not visible at altitude. Warm air moves towards cold air. Layered clouds appear in the sky.

In the second stage, the warm and cold fronts join at the center of the cyclone. An area of ​​warm air mass forms between them. The rest is filled with cold air. Air masses are also in this state during the day.

The third stage is accompanied by the least pressure in the center. It lasts from 12 to 24 hours. The pressure in the center of the cyclone rises sharply, and the wind speed becomes less. The warm air flow stays down. Cold air tries to overcome it. In a certain area, part of the layer is pushed back. As a result, a collision 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, dragging them at a speed of up to 50 km / h. On the distant fronts, a greater speed is achieved than in the center. During this period, due to low pressure, there is a sharp change in the weather.

A developed cyclone passes into the fourth stage and acts for four days or more. The cloud vortex closes in the center and then shifts to the periphery. At this stage, the speed decreases, heavy precipitation falls.

The phenomenon of a cyclone is characterized by a lack of air. Cold currents come in to replenish it. They push warm air up. As it cools, the water condenses. Clouds appear, from which heavy precipitation falls. Here is what a cyclone is and why the weather changes dramatically when it occurs.

Types of cyclones

The duration of the vortex is from several days to weeks. In an area of ​​low pressure, it can last up to a year (for example, the Icelandic or Aleutian cyclone). According to their origin, the types of cyclones differ depending on the place of its occurrence:

• eddies in temperate latitudes
• tropical vortex
• equatorial
• arctic

In the Earth's atmosphere, the movement of masses is constantly formed. Whirlwinds of various sizes are destroyed all the time in it. Warm and cold air currents collide in 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 forms where the surface temperature of the ocean is at least twenty-six degrees. Increased evaporation contributes to an increase in humidity. As a result, vertical air masses rush upward.

With a strong impulse, 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, the air currents turn into hurricanes of destructive force. Of course, not every tropical cyclone brings destruction. When they move to land, they quickly subside.

Movement speed in different stages

1. movement not exceeding 17 m/s is characterized as a disturbance
2. at 17-20 m/s there is some depression
3. when the center reaches 38 m/s, a storm is coming
4. when the forward movement of the cyclone exceeds 39 m/s, a hurricane is observed

In the center of the cyclone, an area of ​​calm weather prevails. Inside, a warmer temperature is formed than in the rest of the air flow, less humidity is observed. The tropical cyclone is the southernmost one, it is smaller and has a higher wind speed.

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

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

Tropical cyclones

Tropical cyclones mainly capture areas of the southeast 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 in the Pacific Ocean - cordonaso
• East Asia - typhoon
• Philippines - Baruyo / Baguyo
• Australia - Willy Willy

The properties of temperate, tropical, equatorial and arctic air masses are easily identified by name. Each tropical cyclone has its own name, such as "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 course. Their boundless energy carries heat and moisture across all latitudes, from the oceans to the continents and back. Moisture and heat on Earth is redistributed due to the constant movement of air masses.

If it were not for the 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 is a powerful force that can destroy, deposit and transfer rock particles from one place to another.

At first, mills worked from the wind, where they ground grain. On sailboats, he helped to overcome long distances of the seas and oceans. Later, wind turbines appeared, with the help of which people receive electricity.

A cyclone and an anticyclone is a natural “mechanism” that carries air masses and affects weather changes. More and more delving into the secrets of what cyclones and anticyclones are, perhaps people will learn to use these natural phenomena with maximum benefit and benefit for humanity.

SYMBOLS ON DOMESTIC

FAX CARDS

1. Goals of the work:

– to study the system of digital and graphic symbols used to plot hydrometeorological elements on a synoptic

2. Benefits

1. Benefits ,-,,,,,.

2. A set of facsimile cards.

3. Brief theoretical information

Any map, including hydrometeorological, is a visual and operational means of reflecting objective reality. In the rapidly changing hydrometeorological conditions of ocean navigation and fishing, facsimile charts, if systematically received on board and the ability to analyze them, can increase the safety of navigation and the efficiency of fishing.

In the practice of navigation and fishing, it is most advisable to use the following charts:

– surface analysis (weather map, synoptic map, surface map) compiled for the main observation periods – 00, 06, 12, l8 h Greenwich Mean Time (GMT). These are the main cards, they are also called actual, abbreviated designation AS – analysis is superficial, surface;

- surface weather forecast for the periods of 12, 24, 36, 48, 72, 96 hours. These are forecast maps, their abbreviation is FS – superficial, surface forecast;

– analysis of wind and waves, in which the characteristics of the actual fields of wind and waves are given (wind direction and speed, direction of movement, height, wave period). Their abbreviation is AX;

– wind and wave forecast – predicted wind and wave fields (wind direction and speed, wave direction and height). Their abbreviation is FX;

- analysis of water temperature, which shows the field of water temperature on the surface of the sea (ocean), averaged over a five-day period, a decade;

– water temperature forecast – predicted (expected) distribution of water temperature on the surface of the ocean (sea) for periods from 1 to 10 days;

– ice conditions – ice conditions (ice edge, concentration, thickness, ice age and position of drifting icebergs).

Facsimile surface weather maps are the main maps reflecting the processes and phenomena in the interacting atmosphere-ocean system.

To distinguish between facsimile maps, a four-letter group indicates in the frame: the type of map and the area for which it was compiled, the name of the meteorological center, the date and time (time) for which it was compiled. For example, in fig. 3.1 in the ASXX group, the letters AS characterize the type of map - surface weather analysis, the letters XX - an area that does not have an index. The RUMS group means the name of the meteorological center (Moscow). The decoding of the letter groups in the frame is given in the manuals,.

The weather radiograms received from ships and coast stations are decoded at meteorological centers and put on a synoptic map with special symbols (in graphical and digital form). Hydrometeorological elements and phenomena are placed in a strictly defined place relative to the circle (punch) depicting the station or the location of the vessel on the map (Fig. 3.2). Next, the cards are subjected to graphic processing; through 5 mbar, isobars are drawn (lines of different atmospheric pressure values), the identified centers of areas of low (cyclones) and high (anticyclones) pressures are designated, respectively, by the letters H and B. Areas occupied by warm and cold air masses, the position and types of atmospheric fronts are applied , areas of extensive precipitation, etc. Knowing the conventional weather symbols (they are given in the manual , in the schedule of facsimile broadcasts, on the stand in the laboratory) and digital designations, the map can be “read”, i.e. receive weather information on board. At the same time, it should be remembered that 5-6 hours pass from the moment of observing weather elements to receiving a map on the ship, so the weather information, as it were, “becomes outdated”.

Fig.3.1. Surface analysis. Moscow

Rice. 3.2. Scheme for applying meteorological values ​​on a synoptic map:

The maps characterizing the state of the atmosphere also include the forecast of the baric field in the surface layer (Fig. 3.3) and the cloud map - nephaanalysis. The cloud map is not given in the laboratory workshop; it is placed in the set of facsimile maps.

The rest of the maps (waves, ice conditions, water temperature on the ocean surface) can be classified as oceanic, i.e. reflecting the state of the waters on the surface of the ocean (Fig. 3.4 - EVIL).

4. Task

1. Study the system of symbols on the surface analysis map - AS. Enter in the notebook the graphic and numerical symbols of one ship station.

2. Consider the position, configuration, and cloudiness density on the satellite photograph. Write down the coordinates of the center of the cyclone and the stage of its development.

3. To study the features of symbols on the prognostic surface map.

4. Understand the system for placing hydrometeorological values ​​on the wave map.

5. Learn the system of symbols used on the maps of water temperature and ice conditions.

5. Work order

Completion of item 1 of the task

The analysis of atmospheric processes (the emergence, development, movement of cyclones and anticyclones, the transformation of air masses and fronts separating them) is carried out using synoptic maps. These charts are the main ones for taking into account the influence of weather on ships and special attention should be paid to their study.

Rice. 3.5. Scheme for applying meteorological values ​​to the wave map:

a - letter designations in accordance with the Code KN-01s;

b - digital and alphabetic designations of hydrometeorological elements and phenomena

Rice. 3.8. Map of temperature analysis in the surface layer according to satellite and ship data

Rice. 3.10. Ice conditions map.

According to the data placed in the corner of the map, you need to find a surface analysis map in the kit (AS), decipher its name, determine for how long it was compiled and study the area for which the map was drawn. Then you should consider the layout of hydrometeorological elements and phenomena at one of the stations, guided by the letter and graphic scheme (Fig. 3.2).

Designations of cloudiness elements (applied with graphic symbols) are given in manuals, and on the stand in the laboratory.

Direction of the wind (dd) is applied with an arrow going to the center of the circle; wind speed ( ff) - plumage (long feather - 5 m / s, short - 2.5 m / s).

The pressure is applied in numbers. Tens, units and tenths of a millibar are indicated, thousands and hundreds are omitted.

The temperature of air and water is applied in degrees Celsius with tenths. Tens, units and tenths of a degree are indicated. It is necessary to select a graphical representation of the weather of any ship station and, using the scheme in (Fig. 3.2), decipher it. Record the data in a notebook.

Isobar systems on domestic maps are drawn through 5 mbar and signed with two digits. Tens and units of millibar are indicated, thousands and hundreds are omitted.

The designation of the front sections is given in Table. 4 allowances.

When studying this topic, you need to know the following concepts:

cyclone– atmospheric perturbation with reduced air pressure (minimum pressure in the center) and with air circulation around the center counterclockwise in the northern hemisphere and clockwise in the southern hemisphere;

anticyclone– atmospheric disturbance with maximum pressure in the center and air circulation clockwise in the northern hemisphere and counterclockwise in the southern hemisphere;

air masses- volumes of air in the troposphere, commensurate in area with large parts of the continents and oceans, possessing certain properties (temperature uniformity in the horizontal direction, a certain type of vertical temperature distribution, humidity and visibility);

front- transitional (frontal) zone between two air masses in the atmosphere. The width of the front zone when it crosses along the normal is up to several tens of kilometers, the length from the center of the cyclone to its periphery is up to 1000 kilometers or more. In the front zone, meteorological elements change abruptly during the transition from one air mass to another, which leads to the development of clouds and the release of precipitation during vertical air rise.

Having studied the map, one should single out the most pronounced cyclones and anticyclones, frontal sections in the area, determine the pressure values ​​in the centers, and consider the wind systems. Establish zones with maximum wind speeds, areas with reduced visibility, centers (on the path of cyclones to the east) of the maximum drop in atmospheric pressure, areas with maximum negative barometric trends.

All these data must be entered in a notebook in the form of a table. 3.1.

p/nIndicator CycloneAnticyclone1Coordinates of centersW=72°00.0 N.L.

D=15°00.0 W

W=62°00.0 N

L=85 about 00.0 E.W=54°00.0 N

D=31°00.0 E

W=75°00.0 N

D=29°00.0 east 2Atmospheric pressure in centers Р=975 mbar

Р=985 mbarР=1044 mbar

P=1024.5 mbar3 Scheme of fronts in cyclonesCold

front There are no fronts in the centers of anticyclones, on the periphery 4 can be observed. Average coordinates of the zone with maximum winds

L=05°00.0 W.L.W=71°00.0 N.L.

D=35 o 00.0 east

L=12°00.0 W.L.W=57°00.0 N.L.

L=80°00.0 E6Coordinates of the center of the zone with the maximum pressure drop (to the east of the center of the cyclone)W=72°00.0 N L=05°00.0 W 7Coordinates of the center of the zone of maximum pressure increase in the rear of the cyclone (to the west of its center)

D=35°00.0 W

The results of determining the wind speed depending on the horizontal baric pressure gradient in different parts of the cyclone are entered in Table. 3.2.

Table 3.2

Note.ΔP/ΔR is the magnitude of the horizontal pressure gradient.

To calculate the wind speed, it is necessary to use the gradient ruler of the USSR Hydrometeorological Center (Fig. 3.11). The ruler is suitable for calculations on polar stereographic projection maps. Latitude values ​​are plotted on the horizontal scale of the ruler; vertical lines are drawn from them. The system of curves means wind speed. To calculate the gradient wind speed, it is necessary to take the distance between the isobars (along the normal to them) drawn through 10 mbar with a compass, then plot this distance on a vertical line corresponding to the latitude of the place. The first distance point will be on the horizontal scale, the second point will be on one of the curves or between the curves. The values ​​of the curve will indicate the speed of the geostrophic wind. The resulting geostrophic wind speed will be greater than the wind speed blowing near the sea surface, therefore, to obtain the surface wind speed, it is necessary to multiply the obtained geostrophic wind speed by a coefficient that takes into account the stratification of the atmospheric surface layer (Table 3.3).

Table 3.3

0.6 Unstable (water temperature is higher than air temperature) 0.0-2.0°

More than 2.0°0.7

Note. If it is not possible to determine the air temperature difference, then a coefficient of 0.6 is taken for the cold part of the year, and 0.8 for the warm half of the year.

Surface weather maps also show information about tropical cyclones. The center of a tropical cyclone is indicated by special symbols:

X - for tropical depressions, in which the wind strength is not known, but there are indications of their further development into a tropical storm. In other cases, a tropical depression is denoted by the sign H;

§ - for cyclones with observed or calculated wind speed from 10 to 32 m/s;

§'- for cyclones with a wind speed of 33 m/s or more.

Near the center of the cyclone, the stage of development of the cyclone is sometimes indicated using the following abbreviations (Table 3.4).

Table 3.4

Map abbreviations indicating the stage of development of a tropical cyclone

From the center, the arrow indicates the direction of the cyclone, at the end of which the speed (km / h) is affixed.

Next to the tropical cyclone (or on the margins of the map) indicate the name of the cyclone in English, the maximum wind (m / s), the direction of the cyclone displacement in rhumbs or degrees.

Completion of item 2 of the task

On forecast surface weather maps, isobars are drawn and centers of low and high pressure are indicated. The centers of cyclones and anticyclones indicate the value of the expected atmospheric pressure for the hour for which the forecast map was compiled. The arrow from the center shows the direction and speed of movement of cyclones and anticyclones (km/h).

In accordance with the basic data placed on the prognostic map, it is necessary to write down in a workbook:

- the area covered by the compiled map;

- the period for which the map was drawn up;

– centers (coordinates) of cyclones and anticyclones;

is the pressure at the center of the cyclone (anticyclone);

- the direction and speed of movement of the main cyclones and anticyclones (if it is given).

Completion of item 3 of the task

As practice shows, the speed and safety of a vessel's navigation at sea is not influenced by the wind, but by the excitement caused by it. Thus, the use of wave charts in the practice of navigation is mandatory.

Wave maps are compiled according to observations for the main periods. Prognostic maps are calculated. They are applied to:

– heights of waves in winds (lines of equal values ​​out);

- directions of wave propagation (arrow, where the waves move from).

In the centers of areas with maximum and minimum wave heights, “MAX” and “MIN” are assigned, respectively. In addition, meteorological data are applied to actual wave maps: wind direction and speed, position of the edge of drifting ice and iceberg distribution zones.

Using the information on the actual and forecast wave maps, the following should be entered in the workbook:

– the name of the map from the frame in the corner of the map (region, observation time) ;

– a scheme for applying meteorological elements at one of the stations, using the scheme shown in fig. 3.5;

are the coordinates of the centers of maximum and minimum waves and the wave heights in them.

Completion of item 4 of the task

Facsimile maps of water temperature are compiled for 5 (sometimes 10) days or longer. Despite a significant averaging period, these charts allow solving many navigational and especially fishing tasks:

- to determine the zones (boundaries) of the distribution of warm and cold currents;

– determine the position of hydrological fronts (areas of the ocean with maximum horizontal temperature gradients);

- determine the direction and nature of the currents (the presence of jets, swirls);

- identify water areas in rising waters;

- choose the most advantageous course of the vessel;

– to choose the habitat of fish and the area of ​​fishing. Analyzing the fields of isotherms (lines of equal values ​​of water temperature), first of all, the region of the ocean that the map covers and the period of observation of the water temperature are established.

The boundaries of warm and cold currents (average coordinates) are established by comparing the current map from the Atlas of the Oceans and the water temperature map. At the same time, the direction of currents and the limits of temperature changes in each of the identified currents are determined. The results of comparisons of the water temperature map and the current pattern of the corresponding area are entered in Table. 3.5.

The gradient zone (front) is usually found in the zone of interaction between warm and cold currents. Visually, it is detected by the maximum spatial convergence (“condensation”) of the isotherms. The degree of “contrast” of the gradient zone is determined by the value of the horizontal temperature gradient (ΔT/ΔN, deg/miles, where ΔT is the water temperature difference in the front zone;

ΔN is the distance in miles along the normal to the isotherms in the front zone).

Table 3.5

Name, boundaries, direction of currents and limits of changes in water temperature in these currents

currentsExtreme boundaries of currents

W= , D=Direction

deg, rhumbLimits of temperature changes, °C Warm currents Gulf Stream W=60°12.0 n.l.

L=60°30.0 W.70-80°

EN024-14North AtlanticW=53°30.0N

L=30°00.0 W.L.45°

NNO 10-14NorwegianW=64°20.0 N

L=04°15.0 W Cold currents20°

NO6-8East Greenland Lat=70°00.0 N L=16°15.0 W.200°; 0-2 Labrador W=55°20.0 N

L=48°30.0 W.180°

It is necessary to enter in the notebook the average coordinates of the frontal zone and the magnitude of the horizontal temperature gradient. The direction of the currents is determined by the nature of the isotherms (the direction of their bulges). In the northern hemisphere, in warm currents, the isotherms are convexly directed to the north, cold ones - to the south (in the southern hemisphere, on the contrary)

The nature of the flow is determined by the degree of linearity of the isotherms. In those areas where they are maximally straightened, the currents have maximum velocities (usually in a stream). In the case of maximum curvature, one can speak of meandering (vorticity) of currents. You should find such areas and enter their coordinates in a notebook.

The water area with the rise of deep waters is characterized by a local area with closed isotherms and low temperatures in the center. As a rule, gradient zones are formed on the periphery of such a rise, and commercial concentrations of fish can be concentrated in them.

It is expedient to place the most advantageous path of the vessel along the axis of the associated current jet, which is located to the right of the greatest concentration of isotherms.

The choice of fish habitat (and fishing) is based on taking into account the so-called optimal temperatures for their habitat. The selection technology is described in the manual and reflected on the stands of the laboratory.

The presence of ice in the high latitudes of the ocean is a significant obstacle to navigation and work at sea. Ice symbols (symbols) used on facsimile ice charts of different countries have a different character, therefore, before reading the ice charts, it is necessary to study the graphic and text explanations placed on the ice charts. You can use aids stand in the laboratory.

When compiling a report on the nature of the ice (the navigation area is set by the teacher), it is necessary to study the terminology of ice (Instruction), find on the map the iceberg removal zones, their number, direction and drift speed.

Since commercial concentrations of fish in high latitudes are often distributed near the edges of drifting ice, it is necessary to identify the general patterns of ice drift. In the general case, ice drifts with the current, but wind drift is superimposed on this general transfer. To determine the wind drift, a certain area is specified on the map and the speed and direction of ice drift are calculated depending on the wind speed. The results of the drift calculation are entered in a notebook in the form of a table. 3.6.

Table 3.6

Ice Drift Calculation Based on a Given Wind Speed

Notes.

1. Ice drift speed is 0.02 knots of wind speed.

2. The drift direction deviates from the wind direction by 30° to the right (in the northern hemisphere) and to the left (in the southern hemisphere).

6. Security questions

1. List facsimile charts, the reception of which is necessary for solving nautical problems.

2. What are the principles for compiling facsimile charts?

3. What is the purpose of plotting the barometric trend and its nature on synoptic charts?

4. Indicate the limits of changes in atmospheric pressure in the centers of cyclones and anticyclones.

5. What graphic symbols are used to map the main elements of the waves?

6. What problems are solved with the help of maps of water temperature on the surface of the ocean?

7. What characteristics of currents are determined using water temperature maps?

8. How are frontal (gradient) zones distinguished on water temperature maps?

9. Why are commercial concentrations of fish observed in waters with maximum horizontal water temperature gradients?

10. List the main Symbols used to characterize sea ice.

11. How are ice drift elements calculated?

7. Reporting form

Laboratory work is carried out in a notebook in the sequence that is set out in these guidelines and should contain:

- brief notes on the main points of work (in accordance with the guidelines);

- answers to control questions.

The work is presented to the teacher for credit.