What is a warm front and how does it manifest itself? Yachting

It turned out that warm air is drawn into the cyclone not throughout its entire eastern (right) half, but in a fairly limited sector located in the southern and southeastern parts of the cyclone between two convergence lines. Cloudiness and precipitation are distributed unevenly in the cyclone. Covering rains fall mainly in front of the first (eastern) line of convergence of air flows, as well as in the center of the cyclone. Showers and thunderstorms are concentrated in a narrow band along the second (western) convergence line. These lines were subsequently called atmospheric fronts. Since in temperate latitudes When cyclones usually move from west to east, the eastern front of the cyclone first passes through the observation point, followed by warm air. This atmospheric front was called a warm front. In the vicinity of a warm atmospheric front, warm air actively advances on the front line, moves almost perpendicular to it, and cold air is transported almost parallel to this line, i.e. slowly retreats from her. Consequently, the warm air mass catches up and overtakes the cold one. Then the western (cold) front of the cyclone approaches the observation point, as it passes the air temperature drops sharply. Near a cold atmospheric front, the dynamics are different: cold air catches up with warm air and rapidly displaces it upward.

The upward sliding covers thick layers of warm air over the entire frontal surface and an extensive system of high-stratus clouds with overlying precipitation arises. The warm front has an anticyclonic curvature and moves towards the cold air. On a weather map, a warm front is marked in red or with blackened semicircles directed in the direction of the front’s movement (Fig. 1). As the warm front line approaches, pressure begins to drop, clouds thicken, and heavy precipitation begins to fall. In winter, low stratus clouds usually appear when a front passes. The temperature and humidity are slowly increasing. As a front passes, temperatures and humidity typically rise quickly and winds pick up. After the front passes, the direction of the wind changes (the wind turns clockwise), its speed decreases, the pressure drop stops and its slight increase begins, the clouds dissipate, and precipitation stops. The field of pressure trends is presented as follows: in front of the warm front there is a closed area of ​​pressure drop, behind the front there is either an increase in pressure or a relative increase (a decrease, but less than in front of the front). The passage of a warm front is usually accompanied by a powerful layer of rain covering the entire sky with heavy rain. The first sign of a warm front is cirrus clouds. Gradually they turn into a continuous white veil of cirrostratus clouds. Warm air is already moving in the upper layers of the atmosphere. The pressure drops. The closer the front line is to us, the denser the clouds become. The sun shines through as a dim spot. Then the clouds drop lower and the sun disappears completely. The wind intensifies and changes its direction clockwise (for example, at first it was easterly, then southeasterly and even southwest). Approximately 300-400 km before the front, the clouds thicken. Light continuous rain or snow begins. But the warm front has passed. The rain or snow has stopped, the clouds are dissipating, warming is coming - a warmer air mass has arrived. The warm front in vertical section is shown in Fig. 2.

If the warm air retreats and the cold air spreads out after it, it means that a cold front is approaching. His arrival always causes a chill. But when moving, not all layers of air have the same speed. As a result of friction with the earth's surface, the lowest layer is slightly delayed, while the higher ones are pulled forward. Thus, cold air falls on warm air in the form of a shaft. Warm air is quickly forced upward and powerful piles of cumulus and cumulonimbus clouds are created. The clouds of the cold front carry showers, thunderstorms, accompanied by strong gusty winds. They can reach very high altitudes, but in the horizontal direction they extend only 20...30 km. And since the cold front usually moves quickly, stormy weather does not last long - from 15...20 minutes. up to 2...3 hours. As a result of the interaction of cold air with the warm underlying surface, cumulus clouds with gaps are formed. Then comes complete clarity.

In the case of a cold front, the upward movement of warm air is limited to a narrower zone and is especially strong in front of the cold wedge, where warm air is displaced by cold air. The clouds here will largely be cumulonimbus with showers and thunderstorms (Fig. 3, Fig. 4). A cold front has a cyclonic curvature (bulges toward warm air) and moves toward warm air. On a weather map, a cold front is marked in blue or with blackened triangles directed in the direction the front is moving (Fig. 1). The flow in cold air has a component directed towards the front line, so cold air, moving forward, occupies the space where warm air was previously located, which increases its instability.

When crossing the line of a warm front, the wind, as in the case of a warm front, turns to the right, but the turn is more significant and sharp - from the southwestern, southern (in front of the front) to the western, northwestern (behind the front). At the same time, the wind speed increases. Atmospheric pressure changes slowly ahead of the front. It may fall, but it can also rise. With the passage of the cold front it begins rapid growth pressure. Behind the cold front there is a closed isallobaric region of pressure growth, and the increase can reach 3-5 hPa/3h. A change in pressure in the direction of its increase (from a decrease to an increase, from a slow increase to a stronger one) indicates the passage of the surface front line.

Thunderstorms and squalls are common ahead of the front. After the front passes, the air temperature drops, often quickly and sharply – by 10 °C or more in 1-2 hours. The mass fraction of water vapor decreases simultaneously with the air temperature. Visibility typically improves as polar or arctic air moves in behind the cold front. In addition, the instability of the air mass prevents condensation near the Earth's surface.

The nature of the weather on a cold front varies markedly depending on the speed of the front's movement, the properties of warm air ahead of the front, and the nature of the upward movements of warm air above the cold wedge. Cold fronts of the 1st type are dominated by an orderly rise of warm air above a wedge of cold air. A type 1 cold front is a passive upward sliding surface. Slowly moving or slowing down their movement fronts belong to this type, mainly on the periphery of cyclonic regions in deep baric troughs. In this case, the clouds are located mainly behind the front line. There is still a difference from the cloudiness of a warm front. Due to friction, the surface of the cold front in the lower layers becomes steep. Therefore, just before the front line, instead of a calm and gentle upward sliding, a steeper (convective) rise of warm air is observed (Fig. 3). Due to this, powerful cumulus and cumulonimbus clouds sometimes appear in the front part of the cloud system, stretching for hundreds of kilometers along the front, with showers in summer, snowfall in winter, thunderstorms, hail and squalls. Over the overlying part of the frontal surface with a normal slope as a result of the upward sliding of warm air, the cloud system represents a uniform cover of stratus clouds. Rainfall ahead of the front after the passage of the front is replaced by more uniform blanket precipitation. Finally, cirrostratus and cirrus clouds appear. The vertical power of the system and the width of the cloud system and precipitation area will be almost 2 times less than in the case of a warm front. The upper boundary of the system is approximately at an altitude of 4-4.5 km. Stratus broken clouds may develop beneath the main cloud system, and frontal fogs may sometimes form. The duration of passage of a cold front of the 1st type through an observation point is 10 hours or more.

Fronts of the 2nd kind in the lower layer of the atmosphere are a passive ascending slip surface, and above them are an active downward sliding surface. Most fast-moving cold fronts in cyclones belong to this type. Here, the warm air of the lower layers is displaced upward by the cold shaft moving forward. The surface of the cold front in the lower layers is very steep, even forming a bulge in the form of a shaft (Fig. 4). The rapid movement of a wedge of cold air causes forced convection of displaced warm air in a narrow space at the front of the frontal surface. Here a powerful convective flow is created with the formation of cumulonimbus clouds, intensifying as a result of thermal convection. The harbingers of the front are altocumulus lentiform clouds, which spread in front of it at a distance of up to 200 km. The emerging cloud system has a small width (50-100 km) and does not represent individual convective clouds, but a continuous chain, or a cloud bank, which sometimes may not be continuous. In the warm half of the year, the upper boundary of cumulonimbus clouds extends to the height of the tropopause. On cold fronts of the 2nd type, intense thunderstorm activity, showers, sometimes with hail, and squally winds are observed. There is strong turbulence and icing in the clouds. Zone width hazardous phenomena weather distance is several tens of kilometers. In the cold half of the year, the tops of cumulonimbus clouds reach 4 km. The width of the snowfall zone is 50 km. This cloudiness is associated with heavy snowfalls, blizzards with visibility less than 1000 m, a sharp increase in wind speed, and bumpiness.

When cold fronts of the 2nd type pass through an observation point, cirrus clouds first appear (3-4 hours before the front line passes near the Earth), which are quickly replaced by altostratus, sometimes lenticular, which are quickly replaced by a mass with showers, thunderstorms, hail, and squalls. The duration of movement of a cloud system with showers and thunderstorms usually does not exceed 1-2 hours. After the cold front passes, the rainfall stops. A feature of cold fronts of both the first and second types are prefrontal squalls. Since in the front part of the cold wedge, due to friction, a steep slope of the frontal surface is created, part of the cold air appears above the warm one. Then there is a “collapse” of cold air masses in front of the advancing cold shaft. The collapse of cold air leads to the displacement of warm air upward and to the appearance of a vortex with a horizontal axis along the front. Squalls on land are especially intense in the summer, when there is a large temperature difference between warm and cold air on both sides of the front and when warm air is unstable. Under these conditions, the passage of a cold front is accompanied by destructive wind speeds. The wind speed often exceeds 20-30 m/s, the duration of the phenomenon is usually several minutes, and gusts are sometimes observed.

Occlusion fronts
Due to downward movements in the cold air at the rear of the cyclone, the cold front moves faster than the warm front and over time catches up with it. At the stage of filling the cyclone, complex fronts arise - occlusion fronts, which are formed when cold and warm atmospheric fronts close.

In the occlusion front system, three air masses interact, of which the warm one no longer comes into contact with the Earth’s surface. The process of displacing warm air into the upper layers is called occlusion. In this case, the rear wedge of cold air of the cyclone closes with the front wedge of cold air. Warm air in the form of a funnel gradually rises upward, and its place is taken by cold air coming from the sides (Fig. 5). The interface that occurs when cold and warm fronts meet is called the occlusion front surface.

In the case of an occluded cold front, precipitation can occur on both sides of the lower front, and the transition from blanket precipitation to showers, if it occurs, occurs not ahead of the lower front, but in close proximity to it. In the case of a warm occlusion front, the vortex of warm air is displaced by warmer air flowing onto a wedge of colder air. The rear wedge of less cold air overtakes the front wedge of colder air, and the cold front, having separated from the Earth's surface, rises along the surface of the warm front.

A weak upward sliding of the rear air along the front air along the occlusion surface can lead to the formation of St-Sc clouds along it, not reaching the level of the ice cores. These will produce some drizzle ahead of the lower warm front.

A warm front is marked in red or with blackened semicircles directed in the direction of the front's movement. As the warm front line approaches, pressure begins to drop, clouds thicken, and heavy precipitation begins to fall. In winter, low stratus clouds usually appear when a front passes. The temperature and humidity are slowly increasing. As a front passes, temperatures and humidity typically rise quickly and winds pick up. After the front passes, the wind direction changes (the wind turns clockwise), the pressure drop stops and its slight increase begins, the clouds dissipate, and precipitation stops. The field of pressure trends is presented as follows: in front of the warm front there is a closed area of ​​pressure drop, behind the front there is either an increase in pressure or a relative increase (a decrease, but less than in front of the front).

In the case of a warm front, warm air, moving towards the cold air, flows onto a wedge of cold air and glides upward along this wedge and is dynamically cooled. At a certain height, determined by the initial state of the rising air, saturation is achieved - this is the level of condensation. Above this level in rising air cloud formation occurs. Adiabatic cooling of warm air sliding along a wedge of cold air is enhanced by the development of upward movements from unsteadiness with a dynamic drop in pressure and from the convergence of wind in the lower layer of the atmosphere. Cooling of warm air during upward sliding along the surface of the front leads to the formation of a characteristic system of stratus clouds (upward sliding clouds): cirrostratus - altostratus - nimbostratus (Cs-As-Ns).

When approaching a point of a warm front with well-developed cloudiness, cirrus clouds first appear in the form of parallel stripes with claw-shaped formations in the front part (harbingers of a warm front), elongated in the direction of air currents at their level (Ci uncinus). The first cirrus clouds are observed at a distance of many hundreds of kilometers from the front line near the Earth's surface (about 800-900 km). Cirrus clouds then become cirrostratus clouds. These clouds are characterized by halo phenomena. The upper tier clouds - cirrostratus and cirrus (Ci and Cs) consist of ice crystals and do not produce precipitation. Most often, Ci-Cs clouds represent an independent layer, the upper boundary of which coincides with the axis of the jet stream, that is, close to the tropopause.

Then the clouds become more and more dense: altostratus clouds (Altostratus) gradually turn into nimbostratus clouds (Nimbostratus), blanket precipitation begins to fall, which weakens or stops completely after passing the front line. As you approach the front line, the height of the base Ns decreases. Its minimum value is determined by the height of the condensation level in the rising warm air. Altolayers (As) are colloidal and consist of a mixture of tiny droplets and snowflakes. Their vertical thickness is quite significant: starting at an altitude of 3-5 km, these clouds extend to heights of the order of 4-6 km, that is, they are 1-3 km thick. Precipitation falling from these clouds in summer, passing through warm part atmosphere, evaporate and do not always reach the Earth's surface. In winter, precipitation from As as snow almost always reaches the Earth's surface and also stimulates precipitation from the underlying St-Sc. In this case, the width of the zone of continuous precipitation can reach a width of 400 km or more. Closest to the Earth's surface (at an altitude of several hundred meters, and sometimes 100-150 m and even lower) is the lower boundary of nimbostratus clouds (Ns), from which precipitation falls in the form of rain or snow; Nimbostratus clouds often develop under nimbostratus clouds (St fr).

Ns clouds extend to heights of 3...7 km, that is, they have a very significant vertical thickness. Clouds also consist of ice elements and droplets, and the droplets and crystals, especially in the lower part of the clouds, are larger than in As. The lower base of the As-Ns cloud system in general outline coincides with the front surface. Since the top of As-Ns clouds is approximately horizontal, their greatest thickness is observed near the front line. At the center of the cyclone, where the cloud system of the warm front is most developed, the width of the cloud zone Ns and the zone of heavy precipitation is on average about 300 km. In general, As-Ns clouds have a width of 500-600 km, the width of the Ci-Cs cloud zone is about 200-300 km. If you project this system on a ground map, then all of it will be in front of the warm front line at a distance of 700-900 km. In some cases, the zone of cloudiness and precipitation can be much wider or narrower, depending on the angle of inclination of the frontal surface, the height of the condensation level, and the thermal conditions of the lower troposphere.

At night, radiative cooling of the upper boundary of the As-Ns cloud system and a decrease in temperature in the clouds, as well as increased vertical mixing as cooled air descends into the cloud, contributes to the formation of an ice phase in the clouds, the growth of cloud elements and the formation of precipitation. As you move away from the center of the cyclone, the upward air movements weaken and precipitation stops. Frontal clouds can form not only over the inclined surface of the front, but in some cases, on both sides of the front. This is especially typical for the initial stage of a cyclone, when upward movements capture the frontal region - then precipitation can fall on both sides of the front. But behind the front line, frontal clouds are usually strongly stratified and post-frontal precipitation is more often presented in the form of drizzle or snow grains.

In the case of a very flat front, the cloud system may be moved forward from the front line. In the warm season, upward movements near the front line acquire a convective character, and cumulonimbus clouds often develop on warm fronts and showers and thunderstorms are observed (both during the day and at night).

In summer, during the daytime, in the surface layer behind the line of a warm front with significant cloudiness, the air temperature over land may be lower than in front of the front. This phenomenon is called warm front masking.

Cloud cover from old warm fronts can also be stratified throughout the front. Gradually these layers dissipate and precipitation stops. Sometimes a warm front is not accompanied by precipitation (especially in summer). This happens when the moisture content of warm air is low, when the level of condensation lies at a significant height. When the air is dry and especially in the case of its noticeable stable stratification, the upward sliding of warm air does not lead to the development of more or less intense cloudiness - that is, there are no clouds at all, or a strip of clouds of the upper and middle tiers is observed.

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See what a “Warm Front” is in other dictionaries:

Occlusion front is an atmospheric front associated with a heat ridge in the lower and middle troposphere, which causes large-scale upward air movements and the formation of an extended zone of clouds and precipitation. Often the front of occlusion... ... Wikipedia

Transition zone (width of several tens of km) between air. masses with different physical properties. There are Arctic. front (between Arctic and mid-latitude air), polar (between mid-latitude and tropical air) and tropical (between tropical and equivalent... ... Natural science. Encyclopedic Dictionary Encyclopedia "Aviation"

atmospheric front- Rice. 1. Scheme of a warm front in a vertical section. atmospheric front transition zone between air masses, parts of the lower layer of the Earth’s atmosphere (troposphere), the horizontal dimensions of which are comparable to large parts of the continents and ... ... Encyclopedia "Aviation"

Atmospheric front (from other Greek: ατμός steam, σφαῖρα ball and lat. frontis forehead, front side), tropospheric fronts, a transition zone in the troposphere between adjacent air masses with different physical properties. An atmospheric front occurs when... ... Wikipedia

Atmospheric front (from other Greek: ατμός steam, σφαῖρα ball and lat. frontis forehead, front side), tropospheric fronts are a transition zone in the troposphere between adjacent air masses with different physical properties. An atmospheric front occurs when... ... Wikipedia

The concept of atmospheric front is usually understood as a transition zone in which adjacent air masses meet different characteristics. The formation of atmospheric fronts occurs when warm and cold air masses collide. They can extend for tens of kilometers.

Air masses and atmospheric fronts

Atmospheric circulation occurs due to the formation of various air currents. Air masses located in the lower layers of the atmosphere are capable of combining with each other. The reason for this is general properties these masses or identical origin.

Change weather conditions occurs precisely due to the movement of air masses. Warm ones cause warming, and cold ones cause cooling.

There are several types of air masses. They are distinguished by the source of their occurrence. Such masses are: arctic, polar, tropical and equatorial air masses.

Atmospheric fronts occur when different air masses collide. Collision areas are called frontal or transitional. These zones instantly appear and also quickly collapse - it all depends on the temperature of the colliding masses.

The wind generated by such a collision can reach a speed of 200 km/k at an altitude of 10 km from earth's surface. Cyclones and anticyclones are the result of collisions of air masses.

Warm and cold fronts

Warm fronts are considered to be fronts moving towards cold air. The warm air mass moves along with them.

As warm fronts approach, there is a decrease in pressure, thickening of clouds and heavy precipitation. After the front has passed, the direction of the wind changes, its speed decreases, the pressure begins to gradually rise, and precipitation stops.

A warm front is characterized by the flow of warm air masses onto cold ones, which causes them to cool.

It is also quite often accompanied by heavy rainfall and thunderstorms. But when there is not enough moisture in the air, precipitation does not fall.

Cold fronts are air masses that move and displace warm ones. There are cold fronts of the first kind and cold fronts of the second kind.

The first type is characterized by the slow penetration of its air masses under warm air. This process forms clouds both behind the front line and within it.

The upper part of the frontal surface consists of a uniform cover of stratus clouds. The duration of the formation and decay of a cold front is about 10 hours.

The second type is cold fronts moving with high speed. Warm air is instantly replaced by cold air. This leads to the formation of a cumulonimbus region.

The first signals of the approach of such a front are high clouds that visually resemble lentils. Their formation occurs long before his arrival. The cold front is located two hundred kilometers from where these clouds appear.

Cold front of the 2nd kind in summer period accompanied by heavy precipitation in the form of rain, hail and strong winds. Such weather can extend for tens of kilometers.

In winter, a cold front of the 2nd type causes a snowstorm, strong winds, and roughness.

Atmospheric fronts of Russia

The climate of Russia is mainly influenced by the North Arctic Ocean, Atlantic and Pacific.

In summer, Antarctic air masses pass through Russia, affecting the climate of the Ciscaucasia.

The entire territory of Russia is prone to cyclones. Most often they form over the Kara, Barents and Okhotsk seas.

Most often, there are two fronts in our country - the Arctic and the polar. They move south or north during different climatic periods.

The southern part of the Far East is influenced by the tropical front. Heavy precipitation in central Russia is caused by the influence of the polar dandy, which operates in July.

A warm front is a moving section between advancing warm air and retreating cold air.

As is known, the frontal surface, like the front line itself, under the “pressure” of warm air masses moves towards cold air. Warm air, being lighter, flows onto the cold air, making a gradual forced rise along the entire frontal surface. As it rises, it cools adiabatically, as a result of which the water vapor present in it condenses and forms a system of clouds. In the immediate vicinity of the front line, where warm air rises along the steeper part of the frontal surface, low nimbostratus clouds (N8) form, from which continuous rain falls in the warm season and snow in the cold season. The width of the precipitation zone in the front part of the warm front varies widely, but on average it is 300-400 km.

Further beyond the zone where the frontal surface becomes higher and flatter, nimbostratus clouds gradually turn into altostratus clouds (Ab), from which light precipitation falls. In summer, due to the high temperature, raindrops falling from the Ae evaporate and do not reach the ground; In winter, light snow falls from them.

As you move further away from the front line, altostratus clouds, already at high altitudes, gradually turn into cirrostratus (Ce), and the latter into cirrus (Ci). These clouds appear at a distance of 80P-1000 km (horizontally) from the warm front line.

Thus, cloud systems of a warm front have a completely natural alternation. As a warm front approaches a given point, the clouds alternate in the following sequence: Si, Ce, Av and N8.

The speed at which a warm front moves varies. On average it is 25 - 30 km/h (maximum 50-60 km/h). From the moment the warm front line appears, it can reach the observation point in 20-30 hours, and the precipitation zone - in 10-15 hours.

Behind the line of the warm front, masses of warm air move, bringing with them their characteristic weather: noticeable and sometimes sharp warming, cessation of precipitation, and the appearance of advective fogs. At the moment the front passes, the wind changes direction - from SE to S and SW (turn to the right).

There are, however, such warm fronts (poorly expressed) that, due to the dryness of the air masses interacting at the frontal surface, do not form the usual tenlophroite clouds and pass without noticeable changes in the weather. The passage of such a warm front is limited only by a slight increase in temperature and a change in wind direction. Partly cloudy and dry warm fronts are most common in southern continental regions.

Thus, warm fronts in most cases, from the point of view of the navigator, bring with them unfavorable weather: prolonged (overwhelming) precipitation, poor visibility and possible increased wind.

The above sequence of cloud changes as well as a gradual drop in pressure can serve as signs of the approach of a warm front.

On a synoptic map, a warm front is indicated by a red line and a single-color print - a black line with oval teeth facing the direction of the front's movement.

Often, when we leave home for several hours, we do not know how the weather will change. Remember the times when you were caught in the rain without an umbrella and looked for shelter or wore clothes that were too warm and felt uncomfortable. Even modern gadgets do not always provide us with the opportunity to quickly find out the weather, but by observing the direction of the wind, cloudiness, sky color, and other signs, we can learn to predict the weather for the near future.

Weather is the state of the atmosphere in a given area, in given time. The main elements of weather are atmospheric pressure, temperature and humidity. The main weather phenomena are wind, clouds, precipitation.

At the same temperature, but different air humidity, with or without precipitation, with or without wind, the weather will be perceived differently by a person. For example, cool weather with wind it is often more difficult for people to tolerate than a colder, but windless one. Weather cannot be characterized by a single element or phenomenon, since it is a combination of them. The concept of weather refers to the current state of the atmosphere, so it experiences continuous changes.

The weather is characterized by variability, which is periodic in nature (daily and seasonal weather changes) and non-periodic in nature (changes associated with the circulation of air masses). Since weather changes are associated with fronts, cyclones and anticyclones, classes are distinguished: warm front weather, cold front weather, cyclonic weather, anticyclonic weather.

Local signs of a warm front.

The passage of a warm front is usually accompanied by thick nimbostratus clouds with continuous rain. The first messenger of a warm front is cirrus clouds, gradually turning into continuous cirrostratus. The pressure drops. The closer to the atmospheric front line, the denser the clouds become. Then the clouds become lower, the wind intensifies and changes its direction. Light rain or snow begins. When the warm front has passed, the rain or snow has stopped, the clouds dissipate, warming sets in - a warmer air mass has arrived.

Clouds characteristic of the passage of a warm front.

Local signs of a cold front.

If warm air retreats and cold air dissipates after it, it means a cold front is approaching. Warm air is quickly forced upward and powerful piles of cumulus and cumulonimbus clouds are created. The clouds of the cold front carry showers, thunderstorms, accompanied by strong gusty winds. Since the cold front usually moves quickly, stormy weather does not last long - from 15-20 minutes to 2-3 hours. As a result of the interaction of cold air with the warm underlying surface, individual cumulus clouds with gaps are formed. Then comes clarity.

Local signs of unstable weather of a cyclonic nature.

If the tops of especially high clouds cease to appear sharply in the sky, as if covered with a veil, then from such a cloud in the fall you can soon expect a downpour or a thunderstorm. If powerful and high cumulus clouds appear during the day, if there was a thunderstorm, but after it it did not get colder, expect another thunderstorm at night. Before a night thunderstorm, fog does not appear in the evening, and dew does not fall. If the sky is cloudy and whitish during the day, the evening dawn is red, and the Sun is covered by a cloud, because of which only its diverging rays are visible, it will rain. The wind is uneven throughout the day: it weakens and then increases sharply. If it intensifies into the night, it further increases the likelihood of unsettled weather. Late autumn, during frosts (but before snow falls) and in early spring after the snow has melted, after sunny day, instead of dew, everything is covered with silvery frost.

Local signs of continued good anticyclonic weather.

Signs that foretell better weather are based on the fact that prolonged bad weather always comes with cyclones. Therefore, improved weather is possible when the cyclone passes. The main sign of improving weather is the erosion of uniform low continuous gray clouds, which is observed during prolonged bad weather. The amount of clouds gradually and evenly decreases. Gaps and gaps form in stratus clouds. Cumulus clouds appear and move in the same direction as the wind near the ground.

Cooling during bad weather is a sure sign of an imminent cessation of precipitation. The stronger the cold snap, the more reliable the sign. It is much warmer in the forest than in the field.

Signs of thunderstorms and showers in hot weather.

During the day it is very warm or hot, the humidity is high, stuffy, steamy. As a thunderstorm approaches, the wind begins to blow towards the thundercloud and then changes its direction by 180°. Cumulus clouds during the day they grow upward and pile up. Then the top of the thundercloud begins to spread out to the sides. The higher the top of a thundercloud reaches, the larger and heavier the rain will be, and the more likely hail will be.

Signs of a possible overnight thunderstorm.

Before a night thunderstorm, the air temperature in the evening almost does not drop; the evening and night are warm and stuffy. In the evening, fog and dew do not appear or quickly disappear. By evening the clouds remain, partially turning into stratocumulus.

Signs of weather change

Worsening weather

The approach of a warm front, i.e. inclement weather and fresh wind after 6-12 hours:

1. Atmospheric pressure gradually decreases.

2. Cirrus claw-shaped clouds quickly moving from the horizon appear, which are gradually replaced by cirrostratus clouds, turning into a denser layer of altostratus clouds.

3. Cirrus and cirrostratus clouds move to the right of the surface wind melting.

4. Increased visibility, increased refraction - the appearance of objects from behind the horizon, mirages; increased audibility of sounds in the air.

5. Smoke from the chimney spreads below.

6. The appearance of small halos and crowns in the corresponding cloud layers; strong twinkling of stars at night.

7. The morning dawn is bright red.

8. In summer there is no dew at night and in the morning.

9. In the evening the Sun sets into the thickening clouds.

Approaching cold front, thunderstorm and storm 1-2 hours before it starts:

1. A sharp drop in atmospheric pressure.

2. The appearance of cirrocumulus, altocumulus tower and lenticular clouds;

3. Wind instability.

4. The appearance of strong interference in radio reception.

5. Clouds are observed in the form of an elongated strip.

6. The appearance of characteristic noise in open water from the approaching thunderstorm or squall. There are no more than 10 minutes left before the squall.

7. Dramatic development cumulonimbus cloudiness.

Better weather

After the passage of a warm front or an occlusion front, i.e. merging of warm and cold fronts, you can expect a cessation of precipitation and weakening winds in the next 4 hours if:

1. The pressure drop stops, the pressure trend becomes positive.

2. The height of the clouds increases, gaps appear in the clouds, nimbostratus clouds turn into stratocumulus and stratus.

3. The wind turns to the right and weakens.

4. Absolute and relative humidity tend to decrease.

5. The excitement begins to calm down.

6. In some places, fog forms over the body of water (at water temperatures below air temperatures).

After the passage of a cold front of the second kind, you can expect a cessation of precipitation, a change in wind direction and clearing in 2-4 hours if there is:

1. A sharp increase in atmospheric pressure.

2. A sharp turn of the wind to the right.

3. A sharp change in the nature of cloudiness, an increase in clearances.

4. A sharp increase in visibility.

5. Lowering the temperature.

Preservation of weather patterns for the near future

General signs:

1. Repetition of meteorological elements of the past day in terms of observations.

2. The type of cloudiness, visibility, the nature of precipitation, the color of the sky, the color of dawn, the audibility of radio reception, the state of the sea, the type and nature of waves, optical phenomena in the atmosphere are similar to those of the past day.

3. If the direction of movement of clouds located on different heights, almost does not change, which means that in the next 6-12 hours we can expect weather without precipitation, with moderate winds.

Good anticyclonic weather with calm winds or calm, clear skies or light clouds and good visibility will persist over the next 12 hours if:

1. High atmospheric pressure does not change or increases.

2. B coastal strip Regularly changing breezes are observed.

3. Individual cirrus clouds that appear in the morning disappear by midday.

4. In the morning and evening, smoke from the chimney rises vertically (at low speed).

5. At night and by morning there is dew on the deck, spar and other objects.

6. The disk of the Sun is deformed at sunrise and sunset.

7. Golden and pink shades of dawn and a silvery glow in the sky are observed.

8. There is a dry haze near the horizon.

9. The sun drops below the clear horizon.

10. Observed green when the stars twinkle.

Bad weather - cloudy, with precipitation, strong wind, poor visibility will persist for the next 6 hours or more:

1.Low or decreasing atmospheric pressure.

2. Absolute and relative humidity are elevated and change little during the day.

3. The nature of cloudiness (nimbostratus, cumulonimbus clouds) does not change.

4. The air temperature is lower in summer and higher in winter.

5. The wind is fresh, does not change strength, character and almost does not change direction.

6. If thunder rumbles in summer in cold, rainy weather, then we must expect prolonged cool weather.

The weather for tomorrow will improve:

1. If cumulus clouds appear in the morning and disappear by evening.

2. If in the evening after bad weather the sun comes out and there are no clouds in the western part of the sky.

3. If the night is quiet and cool, and the moon is setting in a clear sky.

4. Marigolds unfolded their corollas in the morning - to clear weather.

5. Sparrows fly in flocks - for dry and clear weather.

6. Midges “pushing the poppy” - for good weather.

7. The evening forest is warmer than the field - good weather.

8. Beetles fly in the evening - good weather.

10. In the evening, grasshoppers chirp loudly - there will be good weather.

11. The nightingale sings incessantly all night - before the warm day.

12. If the fog falls down and falls on the ground, the weather will be good.

13. Fog that disappears after sunrise also promises good weather.

14. If smoke rises upward, even during bad weather, but without wind, this means good weather.

15. If the rainbow is located in the east and in the afternoon, the weather will improve.

16. Heavy dew in the morning - good weather.

Name at least two signs of a warm atmospheric front

Heavy dew means a clear day.

18. Cumulus clouds move in the same direction as the wind near the ground - towards clear weather.

19. If the sunset is clear, it will be clear.

20. If Milky Way full of stars and bright - for good weather.

21. Cumulus clouds do not develop in height in the afternoon - a sign of the cessation of rain.

22. If, during inclement weather, individual cumulus clouds move quickly across the sky in the same direction in which the wind blows at the surface of the sea, the weather will soon improve, precipitation will stop, and the wind will weaken.

The weather for tomorrow will worsen:

1. If the wind does not subside in the evening, but intensifies.

2. If cumulus clouds appear in the morning and will take shape by midday tall towers or mountains

3. If clouds of all types are visible in the sky at the same time: cumulus, “lamb”, cirrus and wavy.

4. If smoke spreads along the ground.

5. If on a cloudy day the sun shines brightly before sunset.

6. The river will rustle, the frog will scream - it means rain.

7. The sky “sweeps away”, becomes cloudy - it means rain.

8. If the grass is dry in the morning, you should expect rain by nightfall.

9. If sparrows bathe in dust, it means rain.

10. Burdock cones straighten the hooks - before the rain.

11. Flowers smell strong before the rain.

12. Swallows fly up and down - before a storm (check the mooring lines).

13. If there is fog over the forest, it will rain.

14. Smoke without wind clings to the ground: in summer - to rain, in winter - to snow.

15. If in the summer at sunset the clouds thicken, darken and become lead-colored, there will be a thunderstorm at night.

16. Cirrus clouds promise bad weather for two days or more.

17. If the clouds move towards each other, expect bad weather.

18. After a lot of thunder, there’s a lot of rain.

19. In the morning you can hear thunder - in the evening there is rain and wind.

20. The sun sets in the fog - expect rain.

21. Red evening dawn - to the wind, pale - to the rain.

22. Increasing wind towards the end of the day or night with a simultaneous increase in cloudiness means worsening weather.

23. If the sun at sunrise seems a little larger than usual, you need to wait for rain.

24. When two layers of clouds move quickly across or towards each other, this is a sure sign of an imminent sharp deterioration in the weather (precipitation, strong gusty winds).

25. If the leaves of the trees are turned inward, then expect rain.

26. The rapid movement of clouds, opposite to the direction of the wind at the surface, indicates the approach of inclement weather with thunderstorms and strong winds.

27. At sunset, stripes of cirrus clouds are visible in the west, which seem to emerge from one point - to worsening weather.

28. The bright red morning dawn rises high in the sky - to precipitation, the crimson-red evening dawn - to the wind.

Stars

1. If the stars are very frequent in winter - it means cold, in summer - it means clear weather.

2. In summer, few stars are visible in the sky - this means bad weather.

3. When the stars twinkle strongly at night, and clouds in the morning, there will be a thunderstorm at noon.

4. White and red circles around the stars mean good weather, black circles mean rain.

5. If the Milky Way is full of stars and bright, it means good weather, if it’s dim, it means bad weather.

6. Stars fall - towards the wind.

7. And if the stars “play” (shimmer, change brightness) in the summer, it means rain and wind.

Moon

1. A clear round moon in summer means good weather, in winter it means cold weather.

2. The month is red - for rain.

3. A ring around the moon - towards the wind.

4. If the moon is pale or cloudy, then there will be rain, but if it is clear, the weather will be good.

Common signs of weather change

Swifts and swallows fly low - they foretell rain; high - good weather.

The bindweed flowers are closing - rain is coming; bloom in cloudy weather - on sunny days.

Fog spreads across the water in the morning - to good weather, rises - to rain.

When a rainbow appears in the morning, there will be rain, and if in the evening, good weather is possible (especially if the rainbow appears in the eastern part of the horizon).

The greener the rainbow, the more rain there will be.

If there is more red in the rainbow, then the weather will clear up, and if it is blue, the bad weather will drag on.

Thunder in early spring - before the cold.

If thunder booms continuously, there will be hail.

If the sun turns red on the north side during sunset in summer, there will be frost or cold dew.

The sun at sunset and the slope of the sky are red - before the wind.

Jerky, short thunder means good weather, long and rolling thunder means bad weather.

Before it rains, the water in the river turns dark.

If animals and birds are quieter than usual, get ready for bad weather.

If you stand with your back to the wind in an open area, then you should wait for worsening weather only on the left.

If the movement of clouds in the northern hemisphere deviates to the left relative to the direction of the wind at the surface of the water, good weather should be expected. If the clouds noticeably deviate to the right, it means that the front part of the cyclone is passing through this area, and we should expect a significant deterioration in the weather.

If the direction of movement of low clouds slowly turns against the sun, it means that the wind will subside and warm weather will be replaced by colder, stormy weather. If the clouds turn in the direction of the sun, then everything is the other way around.

Atmospheric front. Warm and cold front

Useful information:

Weather can be defined as a certain state of the atmosphere in a particular area at any time. Weather is variable both for a specific area and throughout the Earth.

Weather consists of a number of characteristics. These are air temperature, humidity, precipitation, atmospheric pressure, cloudiness, wind direction and speed. Other characteristics are also used to make special weather forecasts.

The main reason why the weather changes is air temperature. When the temperature changes, other weather characteristics also change. Temperature affects air humidity and atmospheric pressure.

Warm front

As it increases, humidity increases and atmospheric pressure decreases.

Following the increase in air humidity, cloudiness increases. Changes in atmospheric pressure, in turn, lead to the emergence of winds.

The wind moves layers of air that may differ from those in a given area. Therefore, in addition to temperature, wind can also be a primary factor for weather change.

Any region of the troposphere with homogeneous properties is called air mass. The wind moves air masses and brings new weather conditions to the territory. If the air mass was warmer than the one located above the territory, then the air temperature here will rise, the pressure will decrease, and precipitation may fall.

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WEATHER - the state of the atmosphere in certain place V certain time or a period of time (year, month, day). IN environment there is nothing more changeable than the weather: today people are sweltering from the heat; tomorrow they will get wet in the rain; the wind suddenly blows up, sometimes reaching the strength of a hurricane, and then it subsides, becomes warmer, and an amazing peace is established in nature. But the weather also obeys strict laws. It is not always possible to catch them right away, because too many different factors influence the formation of weather.

Weather is characterized by certain meteorological elements. This is atmospheric pressure solar radiation, temperature, air humidity, wind strength and direction, precipitation, cloudiness. Each weather has its own set of symptoms. They are usually closely related to each other. For example, if air pressure decreases in summer, it is usually followed by a decrease in temperature, an increase in humidity, the wind increases, and it begins to rain.

Weather changes can occur every minute or daily, however, a pattern is observed here: weather changes are periodic, that is, repeated over a period of time, in nature.

5. Features of weather conditions of atmospheric fronts.

These are changes in weather characteristics throughout the year associated with the change of seasons, and changes during the day due to the change of day and night. The greatest weather variability is observed in temperate latitudes, especially in areas with continental climate. At equatorial and polar latitudes, seasonal or daily weather changes are weak or practically absent. This is explained by the low variability of radiation conditions at these latitudes.

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Weather. Signs of the weather. Air masses. Atmospheric fronts. Cyclones and anticyclones.

Weather call the state of the lower layer of the atmosphere at a given time and place.

Its most characteristic feature is variability; often the weather changes several times during the day.

Sudden changes in weather are most often associated with changes in air masses.

Air mass – This is a huge moving volume of air with certain physical properties: temperature, density, humidity, transparency.

The lower layers of the atmosphere, in contact with the underlying surface, acquire some of its properties. Warm air masses form above a heated surface, and cold air masses form above a cooled surface. The longer the air mass remains above the surface from which moisture evaporates, the greater its humidity becomes.

Depending on the place of formation, air masses are divided into arctic, temperate, tropical, and equatorial. If the formation of air masses occurs over the ocean, they are called marine. In winter they are very humid and warm, in summer they are cool. Continental air masses have low relative humidity, more high temperatures and are very dusty.

Russia is located in temperate zone, therefore, in the west, maritime temperate air masses predominate, and continental air masses predominate over most of the rest of the territory. Arctic air masses form beyond the Arctic Circle.

When different air masses come into contact in the troposphere, transition regions arise - atmospheric fronts, their length reaches 1000 km, and their height reaches several hundred meters.

Warm front is formed when warm air actively moves towards cold air. Then light warm air flows onto the retreating wedge of cold air and rises along the interface plane. It cools as it rises. This leads to condensation of water vapor and the formation of cirrus and nimbostratus clouds, and then to precipitation.

When a warm front approaches within a day, its harbingers appear - cirrus clouds. They float like feathers at an altitude of 7-10 km. At this time, atmospheric pressure decreases. The arrival of a warm front is usually associated with warming and heavy, drizzling precipitation.

Cold front formed when cold air moves towards warm air. Cold air, being heavier, flows under the warm air and pushes it upward. In this case, stratocumulus rain clouds appear, piling up like mountains or towers, and precipitation from them falls in the form of showers with squalls and thunderstorms. The passage of a cold front is associated with colder temperatures and stronger winds.

Powerful turbulences of air sometimes form at fronts, similar to whirlpools when two streams of water meet. The size of these air vortices can reach 2–3 thousand km in diameter. If the pressure in their central parts is lower than at the edges, this is cyclone.

In the central part of the cyclone, the air rises and spreads to its outskirts. As it rises, the air expands, cools, water vapor condenses and clouds appear. When cyclones pass, cloudy weather usually occurs with rain in summer and snowfall in winter. Cyclones usually move from west to east from average speed about 30 km/h, or 700 km per day.

Tropical cyclones differ from temperate cyclones by being smaller in size and having exceptionally stormy weather. The diameter of tropical cyclones is usually 200–500 km, the pressure in the center drops to 960–970 hPa. They are accompanied hurricane winds up to 50 m/s, and the width of the storm zone reaches 200–250 km. In tropical cyclones, powerful clouds form and heavy precipitation falls (up to 300–400 mm per day). Feature tropical cyclones - the presence in the center of a small, with a diameter of about 20 km, calm area with clear weather.

If, on the contrary, the pressure is increased in the center, then this vortex is called anticyclone. In anticyclones, the outflow of air at the Earth's surface occurs from the center to the edges, moving clockwise. Simultaneously with the outflow of air from the anticyclone, air from the anticyclone enters its central part. upper layers atmosphere. As it descends, it heats up, absorbing water vapor, and the clouds dissipate. Therefore, in areas where anticyclones appear, clear, cloudless weather with weak winds sets in, hot in summer and cold in winter.

Anticyclones cover large areas than cyclones. They are more stable, move at a lower speed, break down more slowly, and often stay in one place for a long time. As the anticyclone approaches, the atmospheric pressure increases. This sign should be used when predicting the weather.

A series of cyclones and anticyclones continuously pass through the territory of Russia. This is what causes weather variability.

Synoptic map- a weather map compiled for a specific period. It is compiled several times a day based on data received from the network weather stations Hydrometeorological Service of Russia and foreign countries. On this map there are numbers and conventional signs weather information is shown - air pressure in millibars, air temperature, wind direction and speed, cloudiness, position of warm and cold fronts, cyclones and anticyclones, precipitation patterns.

To forecast the weather, maps are compared (for example, for November 3 and 4) and changes in the position of warm and cold fronts, the displacement of cyclones and anticyclones, and the nature of the weather in each of them are established. Currently, space stations are widely used to improve weather forecasts.

Signs of stable and clear weather

1. Air pressure is high, hardly changes or increases slowly.

2. The diurnal variation in temperature is sharply expressed: hot during the day, cool at night.

3. The wind is weak, intensifies in the afternoon, and subsides in the evening.

4. The sky is cloudless all day or covered with cumulus clouds, disappearing in the evening. Relative air humidity decreases during the day and increases at night.

5. During the day the sky is bright blue, twilight is short, the stars twinkle faintly. In the evening the dawn is yellow or orange.

6. Heavy dew or frost at night.

7. Fogs over lowlands, increasing at night and disappearing during the day.

8. At night it is warmer in the forest than in the field.

9. Smoke rises from chimneys and fires.

10. Swallows fly high.

Signs of Unsustainable Severe Weather

1. The pressure fluctuates sharply or continuously decreases.

What is an atmospheric front

The daily variation of temperature is weakly expressed or with a violation of the general variation (for example, at night the temperature rises).

3. The wind increases, abruptly changes its direction, the movement of the lower layers of clouds does not coincide with the movement of the upper ones.

4. Cloudiness is increasing. Cirrostratus clouds appear on the western or southwestern side of the horizon and spread throughout the sky. They give way to altostratus and nimbostratus clouds.

5. It’s stuffy in the morning. Cumulus clouds grow upward, turning into cumulonimbus - to a thunderstorm.

6. Morning and evening dawns are red.

7. By night the wind does not subside, but intensifies.

8. Light circles (halos) appear around the Sun and Moon in cirrostratus clouds. There are crowns in the middle-tier clouds.

9. There is no morning dew.

10. Swallows fly low. Ants hide in anthills.