Hello Dear friends! In this article I want to tell you about how various sediments are formed, what kind of process it is and where it is formed.

We have all seen various precipitation in our lives, but most likely we have never thought about where it is formed from, what types of precipitation there are, and what processes are involved in all this, how to determine what the weather will be like tomorrow... Let's consider precipitation and its types.

Precipitation- this is the moisture contained in which falls to the Earth in different types: snow, rain, hail, etc. Precipitation is measured by the thickness of the fallen ball of water in millimeters. On average, the globe receives about 1000 mm of precipitation per year, while in high latitudes and deserts it falls less than 250 mm per year.

Tiny droplets of water vapor in a cloud move up and down rather than hanging. When they fall down, they merge with other droplets of water, but their weight will not allow them to break through the rising air that created them. This process is called “coalescence” (fusion). Let's discuss with you the main types of precipitation.

According to Swedish meteorologist Bergeron's theory, which was put forward in the 1930s, snow and rain are caused by supercooled water droplets that form ice crystals in clouds. Depending on whether these crystals melt during the fall or not, they fall to Earth in the form of rain or snow.

As crystals move up and down in the clouds, new layers grow on them, thus hail forms. This process is called “accretion” (growth).

When water vapor at temperatures from -4°C to -15°C condenses in a cloud, ice crystals stick together and form into snowflakes, thus snow forms.

The shape and size of snowflakes depend on the air temperature and the strength of the winds in which they fall. On the surface, snowflakes form a snow cover that reflects more than half of the sun’s ray energy, and the purest and driest snow reflects up to 90% of the sun’s rays.

This cools snow-covered areas. Snow cover is capable of radiating thermal energy, and therefore even the slight heat it has quickly goes into the atmosphere.

The resulting water when water vapor condenses is rain.

It falls from the clouds and reaches the Earth's surface in the form of liquid droplets. Heavy, light and moderate (storm) rains are distinguished depending on the volume of precipitation that fell in a certain period of time.

The intensity of light rain varies from very low to 2.5 mm/h; moderate rain - from 2.8 to 8 mm/h and with heavy rain more than 8 mm/h or more than 0.8 mm in 6 minutes. When there is continuous cloud cover over a large area, there are continuous continuous rains, usually weak and consisting of small droplets.

In smaller areas, rainfall tends to be more intense and consist of larger droplets. Atmospheric precipitation in the form of very small droplets that fall very slowly from fog or clouds is drizzle. Other precipitations are also distinguished:

freezing rain, ice pellets, snow grains, snow pellets, etc. But I will not write about this, because from the example of basic precipitation written above, you can now clearly understand all these meanings. All this precipitation has the following consequences: ice, frozen trees... and they are very similar to each other.

Cloudiness. Her

can be determined by eye. It varies in oktas on an 8-point scale. For example, 0 oktas – cloudless sky, 4 oktas – half the sky is covered with clouds, 8 oktas – completely cloudy. The weather can be determined without weather forecasts.

It has a local character: somewhere it is raining, and a few kilometers away the weather is clear. Sometimes it may not be kilometers, but meters (it’s clear on one side of the street, but it’s raining on the other), I myself have repeatedly witnessed such rain.

Many fishermen and rural residents, as well as older people, are able to predict the weather in their area much better by studying clouds.

During sunset, red clouds in the sky often guarantee clear weather the next day. Thunderstorms in summer and hail in winter carry copper-colored clouds with bright silvery edges. The storm is foreshadowed by the dawn sky covered with blood-red spots.

The end of a period of stable weather is often heralded by a sky covered in “lamblets” of cirrocumulus clouds. Changes in weather are often indicated by cirrus clouds ("horses tails") high in the sky. Thunderstorms with rain, snow or hail usually bring cumulonimbus clouds.

You can find out more about all types of clouds 🙂

Clouds are made up of very small water droplets or ice crystals floating in the air. These droplets and crystals are so small that under the influence of gravity they only slowly fall down.

They can be compared to tiny specks of dust floating in the air, which we see in a bright ray of sunlight penetrating the window of a dim room.

When cloud droplets and crystals increase in size and become heavier, they begin to fall faster and rain or snow falls from the cloud.

At temperatures above 0°, the cloud consists, of course, only of water droplets: ice melts at this temperature. In very cold air, the cloud usually consists of only ice crystals without any water droplets.

However, in mild frost, the cloud may consist of a mixture of water droplets and ice crystals: it is from such clouds that precipitation usually falls.

In any cloud, water vapor is in a saturated state, i.e., the space within the cloud contains greatest number water vapor that is possible at a given temperature.

If this were not the case, then the drops that make up the cloud would immediately evaporate and the cloud would melt.

What happens in a cloud consisting of only water droplets if, for some reason, ice crystals fall into it? Due to the property of ice to attract moisture, ice crystals begin to grow, the amount of water vapor in the cloud decreases, the air ceases to be saturated, and water droplets begin to evaporate. Thus, the crystals gradually grow due to the reduction of droplets And turn into snowflakes. Grown snowflakes fall out of the cloud, snowfall begins.

It would seem that such a process can only cause snow to fall and does not explain rain in any way. However This not this way. IN In the troposphere, the temperature decreases with altitude, and even on the hottest day, frost reigns at an altitude of several kilometers above. Therefore, almost all summer rain (first appears at the top as snow, and only then, falling and falling into the lower warm layers, snowflakes melt and reach the surface of the Earth in the form of raindrops.

Air masses bring warming and cooling

As we already know, in our latitudes and in the polar countries, air in huge flows (often up to a thousand kilometers in diameter) continuously moves around the centers of cyclones and anticyclones.

These air currents bring us heat or cold from those countries where they are moving from.

Sudden warming is caused by the arrival of a warm air mass that moves from warm to colder areas. A warm air mass, moving into colder areas, turns out to be much warmer than the earth's surface above which. she is moving. Contact with this surface causes continuous cooling from below. Sometimes the air layers adjacent to the ground can be even colder than the upper layers.

The cooling of the warm air mass coming from below the Earth causes condensation of water vapor in the lowest layers of air, and as a result, clouds form and precipitation falls. These clouds are located low. They often descend to the Earth and turn into continuous fogs.

The thickness of the cloud layer is small: usually it does not exceed several hundred meters.

In the lower layers of the warm air mass, all seasons of the year are quite warm (in winter it brings us thaws), and ice crystals usually do not exist here. Therefore, low clouds of warm air mass usually consist of only water droplets and cannot produce heavy precipitation.

Sometimes only a light, drizzling rain falls, which does not even wet the roofs of the houses.

Clouds of warm air mass cover the entire sky with an even or slightly wavy continuous cover and stretch for hundreds and thousands of kilometers. They are called stratus (if they are smooth) or stratocumulus (if they are wavy).

The complete opposite of a warm air mass is a cold one. air weight. It moves from cold to warm areas and brings cooling. Moving to the warmer earth's surface, the cold air mass is continuously heated from below. When heated, not only does condensation not occur, but even the formed already clouds and fogs should evaporate. However, the sky does not become cloudless, only in this case clouds form for completely different reasons than in a warm air mass. Remember what happens to water in a vessel when it is put on fire. Streams of warm water rise from the bottom of the vessel, and streams of warm water fall to the bottom cold water. Something similar happens in cold air. mass, heated by the warm earth's surface. In addition, when heated, all bodies expand and their density decreases. When the lowest layer of air heats up and expands, it becomes more light and seems to float up in the form of separate bubbles or jets. In its place, heavier layers of cold air descend.

Air, like any gas, heats up when compressed and cools when expanded. When air rises, it experiences conditions of lower pressure, since atmospheric pressure becomes weaker with altitude. Under these conditions, the air must expand and therefore cool. Its temperature becomes 1° lower every 100 m of ascent. As the air rises higher and higher, it becomes colder, until finally, at some point certain altitude, condensation and cloud formation will not begin in it.

Descending air jets enter a layer with stronger pressure and heat up due to compression. Not only does no condensation occur in them, but even those parts of the clouds that were carried away by this downward flow evaporate and dissipate.

Therefore, clouds of cold air masses are isolated clouds, or “heaps,” of clouds piled up in height with gaps between them. Such clouds are called cumulus, or cumulonimbus. Clouds of cold air mass are in every way opposite to clouds of warm air mass. They never descend to the Earth and do not turn into fogs, and their thickness from base to top can be very large - up to -8 km. These clouds rarely cover the whole visible the firmament, and between them there are usually gaps of blue sky.

Such clouds penetrate many layers of the atmosphere from bottom to top. Rising air currents carry water droplets with them into those high cold layers, which always contain thin ice crystals. As soon as the cloud grows to a layer with ice crystals, its top immediately begins to cloud over, loses its characteristic “cauliflower” shape and the cloud turns into a cumulonimbus. From this moment on, precipitation will begin to fall rapidly from the cloud - heavy summer showers and heavy winter snowfalls.

In summer, such downpours are often accompanied by thunderstorms and hail, and in autumn and spring, pellets - ice balls smaller than hailstones - sometimes fall out of cumulonimbus clouds. Precipitation of the cold air mass, although heavy, does not last long, because the cumulonimbus cloud covers only a small area of ​​the sky; it is quickly carried by the wind, and soon the sky clears. Therefore, the weather in a cold air mass is very unstable: either heavy rain or heavy snow falls, or the bright sun shines.

There are many physical and geographical phenomena occurring in nature that are explained by various reasons. Such phenomena include the natural processes described below. All of them are interconnected with the continuous evaporation of water from the surface of seas, lakes, rivers, oceans and other bodies of water. You can learn more about how dew, frost, rain and snow are formed by reading this article.

General information: factors influencing weather

IN different places On planet Earth, air humidity varies due to differences in climate and the distribution of internal water volumes. For example, above the surface of equatorial seas the humidity is highest, and above arid deserts it is very low. Although the content of water vapor in the air is small (it is not even visible), it is this that determines the weather conditions.

Before we find out how rain is formed, it is worth noting that in addition to evaporation, another process plays an important role - condensation. It occurs in nature in different ways: the formation of dew or frost, rain or snow.

Snow, like rain, is the end result below the described chain of natural processes. And in order to understand what happens in nature during such phenomena, one should first of all turn to physical laws.

Dew

How is dew, frost, and rain formed? Their occurrence is an interconnected process. First, let's find out how dew is formed. You can see it only in the early morning. Where does it come from?

Water evaporates from the surface of reservoirs, rivers, lakes and even plants on a hot summer day. When the temperature drops (at night), it can reach values ​​at which water vapor becomes saturated. This is the dew point. At that moment, the saturated steam condenses and settles on the soil and on the leaves of plants. Dew can only be seen in the early morning, then it evaporates again under the influence of sunlight.

Origin of frost

The process of frost formation is similar to the formation of dew, but there is one difference. Frost occurs only in the cold season ( late autumn and winter).

Frost is an uneven and very thin layer of ice crystals formed during the sublimation of water vapor from the air on grass, soil and other ground objects at negative temperatures (lower than air temperature).

Moreover, depending on the temperature, the crystals have different shapes: in mild frosts, the crystals are usually in the form of hexagonal prisms, in moderate frosts - in the form of plates, and in severe frosts - in the form of blunt-ended needles. The most favorable conditions for the occurrence of this process are quiet good nights and rough surfaces with low temperature conductivity. Strong wind is an obstacle to the formation of frost, and weak frost, on the contrary, contributes to its formation, since it increases the contact of increasing masses of moist air with the cold surface.

Often in fiction and among the people, crystalline frost is called frost. And in order not to get confused, we must remember that frost usually does not form on thread-like surfaces.

Like dew, it can only be observed in the morning due to the fact that the night is usually much colder than the day.

Precipitation is of no small importance in nature (in the water cycle) and in the life of numerous animals and plants. They are formed as follows. From the surfaces of numerous natural reservoirs in huge quantities The water evaporates and rises several thousand meters upward, where the temperature is lower. There, the steam condenses and transforms into tiny droplets, which subsequently fly chaotically in the atmosphere. Huge volumes of such droplets represent clouds, which under the influence of air masses are transported over incredibly long distances (up to several thousand kilometers).

Colliding with each other during such a long movement, they turn into larger drops, which then fall to the ground in the form of rain. Now we understand how rain is formed.

And snow occurs in the same way, but only in the cold season, when at altitude there is a temperature (less than zero) at which steam condenses. As a result, not water drops are formed, but ice crystals.

About the intensity of rain

How rain is formed is clear and understandable. Now about the drops. Same shape Raindrops can vary in size from 0.5 millimeters to 6 millimeters in diameter. They fly from a great height, breaking onto the ground into numerous tiny drops.

If they do not correspond to the above parameters, then the drops are drizzle.

To a large extent, the intensity of rain depends on the regions, since in hotter climates the earth's surface heats up more strongly and quickly, which contributes to the emergence of a more powerful flow of water vapor, which subsequently rises into the atmosphere.

Conclusion

The most curious process in all these described phenomena is how rain is formed. It is surprising that under the influence of air currents these small drops are transported over considerable distances, covering thousands and thousands of kilometers. It turns out that the beginning of this continuous chain and its end can be located at quite large distances from each other.

The formation of frost and dew, as well as snow and rain, are curious geographical and physical phenomena that can be explained differently from each point of view.

The main thing is that any precipitation plays an important role in the endless water cycle and in the life of all living things that exist on the planet.

Precipitation patterns and types are closely related to cloud shape and structure. Based on the nature of precipitation, precipitation is divided into shower, heavy and drizzling.

Very intense, but short-lived. The suddenness of the beginning and end of the loss is very characteristic of them. Observed over a small area. They fall from cumulonimbus clouds in the form of large drops or large flakes of snow. Rainfall can also fall in the form of sleet, hail, snow or ice pellets.

Covering precipitation is moderate, lasting from several hours to several days. Usually fall from nimbostratus clouds, sometimes from altostratus, stratocumulus, stratus and other clouds before the passage of a warm front or a warm occlusion front; they capture large spaces along the front, up to 400 km wide or more.

Drizzle- this is either precipitation in the form of very small droplets, almost invisible to the eye (drizzle), or very small snowflakes; usually fall from dense stratus clouds or fog.

Rain and snow

If during cloudy weather with precipitation rain or snow falls from time to time and is quite heavy, this is a sign of improving weather.

Weakening rain or snow in the evening foretells better weather.

Heavy rain or snow at night or early in the morning with little wind or calm most often foreshadows a sunny day (clearing usually occurs around noon).

Intense rain or snow in the morning with strong or stormy winds is a sign bad weather all day.

If the rain or snow stops in the afternoon or evening without clearing the sky, then expect more rain or snow to fall the next day.

Warm rain most often falls when the atmospheric pressure, and cold - when increasing.

The heaviest snowfalls and severe blizzards usually occur at temperatures close to 0°. The stronger the frost, the less likely snowfalls and blizzards are.

If it rains before the wind, we must wait for the wind to increase further.

Showering with sunshine means it will rain again tomorrow.

Most often, hail falls for a short period of time and over a limited area, usually in the form of a narrow strip or two parallel strips. Hail is observed only at positive temperatures from cumulonimbus clouds.

Hailfall is almost always associated with the passage of a cold front or a cold-type occlusion front and is accompanied by thunderstorms, showers and squalls, which mainly occur in the northern and southern hemispheres on the western side of the horizon.

Dew and frost

On a clear night with little wind or calm, due to heat loss by radiation, the earth's surface and the adjacent layer of air are greatly cooled. When the temperature of the underlying surface and the temperature of the surface layer of air fall below the dew point, condensation of water vapor will occur if the dew point is above 0°, or sublimation if the dew point is below 0°. In the first case, droplets of water - dew - form on the earth's surface and objects, including on the upper deck of ships, in the second - ice crystals - frost.

The appearance of dew and frost is favored by cloudless, quiet weather, long nights, and high absolute and relative air humidity.

Heavy dew or frost that forms after sunset and disappears only after sunrise is a sign of anticyclonic weather. Moreover, if there is calm or light wind after sunrise, then one can expect that anticyclonic weather will last 12 hours or more, but if moderate wind is observed, then such weather will stop for 6 hours or more.

Dew or frost that forms after sunset and disappears before sunrise is a sign of a transition to cyclonic weather, often within the next 12 hours.

Heavy evening dew (or frost) is a sign of good weather, but if it forms during fog, it indicates an impending change to cyclonic weather.

A quiet, clear night without dew or frost is a sign of a transition to cyclonic weather with precipitation in the next 6 - 12 hours.

Liquid and solid plaque

The formation of liquid or solid deposits on vertical objects, observed most often in the cold season, is a sign of the spread of a warm, stable air mass to the area; prolonged cloudy weather with low stratus clouds, fog, drizzling precipitation and weak winds can be expected.

The formation of liquid deposits in the warm season, which does not happen often, is a sign of heavy rainfall, sometimes thunderstorms.

Fogs

Fog is the condensation of water vapor in the ground layer of air, in which the horizontal visibility of objects becomes less than 0.6 kbt. Thin fog, in which the horizontal visibility is from 0.6 kbt to 6 miles, is called haze.
According to the conditions of formation, fogs are divided into three types: radiation, formed as a result of night cooling of the earth's surface, advective, occurring when a warm mass of air moves onto a cold underlying surface; evaporation fogs that form over a warm water surface in the cold season.

Radiation fogs occur in the coastal strip of the sea and on the shore in low and damp places, spreading like a white veil; After sunrise, such fogs dissipate.

Fogs of advection and evaporation differ from radiation fogs by their long duration of existence and enormous extent of distribution. Over the oceans and seas, they are observed both in coastal and open areas.

To predict upcoming weather highest value have radiation fogs.

1. Ground radiation fog (low fog - up to 2 m), formed after sunset and dissipating only after sunrise, is a sign that anticyclonic weather with calms and weak winds will last 12 hours or more.
2. Ground radiation fog, which forms after sunset and dissipates before sunrise, is a sign of a transition to cyclonic weather in the next 6 to 12 hours.
3. Continuous radiation fog (fog in which the sky is not visible), forming after sunset during calm or light winds and dissipating in the morning or before noon, is a sign that anticyclonic weather will last 12 hours or more.
4. Continuous fog that forms at any time of the day with a moderate wind at sea, often appearing in the form of a wall moving with the wind, is a sign that such weather will last 6 hours or more.
5. Often during the night the valleys are filled with a thick layer of dense fog, which rises in the morning and turns into low stratus clouds and gradually dissipates. Sometimes in the morning, drizzle falls from the clouds. Such fog is a sign that calm anticyclonic weather will persist for a day or more.

The cyclone forced to measure the height of snow cover in the middle zone and in the north-west of Russia

By 10 a.m., observers at many weather stations in the area where the cyclone had already passed had to measure the depth of the snow cover. The first snowdrifts in some places grew up to 10-14 cm in Latvia and Estonia; in Lithuania their height is smaller - up to 4 cm. And in the areas of the non-black earth zone middle zone In European Russia, snow remained on the ground in the morning. In the southeast of the Leningrad region the most snow fell - also up to 12-14 cm. In the Pskov, Vologda and Kostroma regions the height is up to 4-6 cm, in the Novgorod, Tver, Moscow, Yaroslavl, Vladimir and Ivanovo regions its height is still less - up to 1-3 cm.

Autumn and winter cyclones can bring snow, rain, freezing rain, and freezing rain.

In the part of the cyclone where the warm atmospheric front is located, warm air creeps onto a wedge of cold air located near the ground. As a result, in front of the surface front line, a “sandwich with a warm filling” is obtained, in which warm air is located between two cold layers. Of particular interest is the case when the temperature in cold air is negative, and in warm air it is positive. In the zone of such an atmospheric front, a wide range of precipitation can be observed - from snow to rain.

Snow falls ahead of the front when the temperature throughout the troposphere is negative. If precipitation, which begins to fall in the form of ice crystals/snowflakes, passes through a layer of warm air below that is thick enough for it to melt, it turns into water droplets. If the thickness of the layer of cold air into which the drops then fall and continue to fall down is large, then they manage to become covered with an icy shell - freezing rain is formed. If the layer of cold air is relatively thin and located near the surface of the earth, then raindrops entering it become supercooled, but do not have time to freeze until they come into contact with the cold surface of the earth, wires, tree branches, etc. This is freezing rain. If a warm layer of air extends to the surface of the earth, precipitation continues to fall in the form of rain.

In the zone where freezing rain and freezing rain are observed, ice forms, which is an ice crust, both on horizontal and vertical (!) surfaces. Ice is a dangerous phenomenon when the diameter of its deposits exceeds 20 mm. Although problems begin to appear when only the fact of ice is still noted - it is already very difficult to move on a surface covered with a crust of ice (sometimes the coefficient of adhesion is simply close to “0”), the car may become covered with a crust of ice, and it is difficult to open it and clean the windows, not to mention more serious things.

If the temperature in the warm sector rises to positive values, the growth of ice stops and it quickly collapses. If the temperature does not go to “+”, then this is very bad - ice can persist for a very long time on wires, tree branches, on vertical surfaces, where it is difficult to “lime” it with reagents, as was the case at the end of December 2010 at the ETR Center.

Wet snow often falls in winter. Snow that falls at positive temperatures close to 0°, when snowflakes partially melt or when rain falls along with snow. Snowflakes of wet snow usually stick together into flakes. Wet snow, sticking to wires and tree branches, increases the load on them. The diameter of wet snow deposits exceeding 35 mm is considered dangerous. Wet snow is observed at positive, close to zero, temperatures near the ground, when snowflakes partially melt or when rain falls along with snow. It is interesting to consider the case of wet snow, when the distribution of warm and cold air in height is opposite to that observed during freezing rain. In this case more cold air lies above a layer of warmer air. Here everything depends on the temperature at the surface of the earth and the rate of its decrease with height. These two factors determine the thickness of the positive temperature layer.

a) the temperature at the surface of the earth is low, but decreases slowly with height. In this case, a significant thickness of the layer with a positive temperature is needed for the snow to completely melt;

b) the temperature at the surface of the earth is higher, but with height it quickly decreases; the snow has time to melt with a smaller layer thickness.

If its thickness is less than 60 m, then almost 90% of precipitation will fall in the form of snow. If the height of the layer with a positive temperature is about 275 m, then approximately half of the precipitation will be snow and half will be rain. If the height of the layer with a positive temperature is above 300 m, then the probability of snowfall will be less than 50%.

In fact, in each specific synoptic situation, deviations from the above schemes are possible depending on the characteristics of the vertical distribution of temperature, relative humidity of air masses, speed of movement and length of the frontal zone, etc. All these subtleties are taken into account by weather forecasters when forecasting the phase and intensity of precipitation. But still, in order not to create confusion and confuse consumers, forecasts use a more general typification of precipitation by phase without much detail, limiting it to the terms “snow”, “sleet”, “rain”, or a combination thereof. If freezing precipitation (rain, drizzle, freezing rain) that form ice, then in the forecasts it simply sounds like “ice”. Such phenomena are provided for in short-term weather forecasts (for a period of 12 to 72 hours, or 3 days).