Atmospheric precipitation falling at negative air temperature. Formation and types of precipitation. What are the precipitation

Rain, snow or hail - we have been familiar with all these concepts since childhood. To each of them we special treatment. So, rain evokes sadness and dull thoughts, snow, on the contrary, amuses and cheers up. But hail, for example, few people love, as it is capable of causing enormous damage to agriculture and serious injuries to those who find themselves on the street at this time.

We have long since learned how to outward signs determine the approach of certain precipitation. So, if in the morning it is very gray and cloudy outside, precipitation in the form of prolonged rain is possible. Usually such rain is not very heavy, but can last all day. If thick and heavy clouds appeared on the horizon, precipitation in the form of snow is possible. Light clouds in the form of feathers portend heavy rain showers.

It should be noted that all types of precipitation are the result of very complex and very long processes in the earth's atmosphere. So, in order to form ordinary rain, the interaction of three components is necessary: the sun, the surface of the Earth and the atmosphere.

Precipitation is...

Precipitation is water in liquid or solid state that falls out of the atmosphere. Precipitation can either fall on the surface of the Earth directly or settle on it or on any other objects.

The amount of precipitation in a particular area can be measured. They are measured by the thickness of the water layer in millimeters. Wherein solid types precipitation is pre-melted. The average amount of precipitation per year on the planet is 1000 mm. In no more than 200-300 mm falls, and the driest place on the planet is where the recorded annual precipitation is about 3 mm.

Education process

How they are formed different kinds precipitation? The scheme of their formation is one, and it is based on continuous Let us consider this process in more detail.

It all starts with the fact that the Sun begins to warm up. Under the influence of heating, the water masses that are contained in the oceans, seas, rivers, are converted into mixing with air. Vaporization processes occur throughout the day, constantly, to a greater or lesser extent. The volume of vaporization depends on the latitude of the area, as well as on the intensity of solar radiation.

Further, moist air heats up and begins, according to the immutable laws of physics, to rise up. Having risen to a certain height, it cools, and the moisture in it gradually turns into drops of water or ice crystals. This process is called condensation, and it is these water particles that make up the clouds that we admire in the sky.

Droplets in the clouds grow and become larger, taking in more and more moisture. As a result, they become so heavy that they can no longer be held in the atmosphere, and fall down. This is how atmospheric precipitation is born, the types of which depend on specific weather conditions in a particular area.

The water that falls on the surface of the Earth eventually flows in streams into rivers and seas. Then the natural cycle repeats over and over again.

Atmospheric precipitation: types of precipitation

As already mentioned here, there are a huge number of varieties precipitation. Meteorologists distinguish several dozen.

All types of precipitation can be divided into three main groups:

drizzling;
overlay;
storm.

Precipitation can also be liquid (rain, drizzle, fog) or solid (snow, hail, frost).

Rain

This is a type of liquid precipitation in the form of water droplets that fall to the ground under the influence of gravity. The size of the droplets can be different: from 0.5 to 5 millimeters in diameter. Raindrops, falling on the water surface, leave diverging circles of perfectly round shape on the water.

Depending on the intensity, the rain can be drizzling, patchy or torrential. There is also a type of precipitation such as rain with snow.

This special kind atmospheric precipitation, which occur at sub-zero air temperatures. They should not be confused with hail. Freezing rain is drops in the form of small frozen balls, inside of which there is water. Falling to the ground, such balls break, and water flows out of them, leading to the formation of dangerous ice.

If the intensity of the rain is too high (about 100 mm per hour), then it is called a downpour. Showers form on cold atmospheric fronts, within unstable air masses. As a rule, they are observed in very small areas.

Snow

These solid precipitations fall at sub-zero air temperatures and take the form of snow crystals, colloquially referred to as snowflakes.

During snow, visibility is significantly reduced, with heavy snowfall it can be less than 1 kilometer. During severe frosts light snow can be observed even with a cloudless sky. Separately, such a type of snow as sleet stands out - this is precipitation that falls at low positive temperatures.

hail

This kind of solid atmospheric precipitation is formed at high altitudes (at least 5 kilometers), where the air temperature is always lower - 15 ° C.

How is hail produced? It is formed from drops of water that either fall or rise sharply in eddies of cold air. Thus, large ice balls are formed. Their size depends on how long these processes took place in the atmosphere. There were cases when hailstones weighing up to 1-2 kilograms fell on the ground!

A hailstone in its internal structure is very similar to an onion: it consists of several layers of ice. You can even count them, like you count the rings on a cut tree, and determine how many times the droplets have made rapid vertical journeys through the atmosphere.

It is worth noting that hail is a real disaster for Agriculture, because he can easily destroy all the plants on the plantation. In addition, it is almost impossible to determine the approach of hail in advance. It starts immediately and usually happens in summer season of the year.

Now you know how precipitation is formed. The types of precipitation can be very different, which makes our nature beautiful and unique. All the processes taking place in it are simple, and at the same time ingenious.

First of all, let's define the very concept of "atmospheric precipitation". In the Meteorological Dictionary, this term is interpreted as follows: “Precipitation is water in a liquid or solid state that falls from clouds or is deposited from the air on the surface of the earth and on objects.”

According to the above definition, precipitation can be divided into two groups: precipitation released directly from the air - dew, hoarfrost, frost, ice, and precipitation falling from clouds - rain, drizzle, snow, snow pellets, hail.

Each type of precipitation has its own characteristics.

Dew represents the smallest droplets of water deposited on the surface of the earth and on ground objects (grass, leaves of trees, roofs, etc.). Dew forms at night or in the evening on clear, calm weather.

Frost appears on surfaces cooled below 0 °C. It is a thin layer of crystalline ice, the particles of which are shaped like snowflakes.

frost- this is the deposition of ice on thin and long objects (tree branches, wires), formed at any time of the day, usually in cloudy, foggy weather at low temperatures (below - 15 ° C). Hoarfrost is crystalline and granular. On vertical objects, frost is deposited mainly on the windward side.

Among the precipitation earth's surface, special meaning It has ice. It is a layer of dense transparent or cloudy ice, growing on any objects (including trunks and branches of trees, shrubs) and on the surface of the earth. It is formed at an air temperature of 0 to -3°C due to the freezing of drops of supercooled rain, drizzle or fog. The crust of frozen ice can reach a thickness of several centimeters and cause branches to break off.

Precipitation falling from the clouds is divided into drizzling, overflowing and torrential.

Drizzling precipitation (drizzle) composed of very fine water droplets less than 0.5 mm in diameter. They are of low intensity. These precipitations usually fall from stratus and stratocumulus clouds. The droplets fall so slowly that they seem to be suspended in the air.

Heavy rainfall- it is rain, consisting of small water droplets, or snowfall from snowflakes with a diameter of 1-2 mm. These are long-term precipitation falling from dense altostratus and nimbostratus clouds. They can last for several hours or even days, capturing vast territories.

heavy rainfall has great intensity. These are large-drop and uneven precipitation, falling both in liquid and solid form (snow, groats, hail, sleet). The downpour can last from several minutes to several hours. The area covered by a shower is usually small.

hail, which is always observed during a thunderstorm, usually together with heavy rain, is formed in cumulonimbus (thunderstorm) clouds of vertical development. It usually falls in spring and summer in a narrow band and most often between 12 and 17 hours. The duration of the hail fall is calculated in minutes. Within 5-10 minutes, the ground can be covered with a layer of hailstones several centimeters thick. With intense hail, plants can be damaged to varying degrees or even destroyed.

Precipitation is measured by the thickness of the water layer in millimeters. If 10 mm of precipitation fell, then this means that the layer of water that fell on the surface of the earth is 10 mm. And what does 10 mm of precipitation mean for a plot of 600 m 2? It's easy to calculate. Let's start the calculation for an area equal to 1 m 2. For her, this amount of precipitation will be 10,000 cm 3, i.e. 10 liters of water. And this is a whole bucket. This means that for an area equal to 100 m 2, the amount of precipitation will already be equal to 100 buckets, but for an area of six acres - 600 buckets, or six tons of water. That's what 10 mm of precipitation is for a typical garden plot.

Surely, each of us has ever watched the rain through the window. But have we thought about what kind of processes occur in rain clouds? What types of precipitation can receive? That is what got me interested. I opened my favorite home encyclopedia and settled on the section titled "Types of Precipitation". What was written there, I'm going to tell.

What are the precipitation

Any precipitation falls due to the enlargement of elements in the clouds (for example, water droplets or ice crystals). Having increased to a size at which they can no longer be in suspension, the drops fall down. Such a process is called "coalescence"(which means "fusion"). And the further growth of drops occurs already in view of their merging in the process of falling.

Atmospheric precipitation often takes quite different types. But in science there are only three main groups:

massive precipitation. These are the precipitations that usually fall during very long period with medium intensity. Such rain covers itself large area and falls from special nimbostratus clouds that cover the sky, not letting in light;
rainfall. They are the most intense, but short-lived. Originate from cumulonimbus clouds;
drizzling rain. They, in turn, are made up of small droplets - drizzle. This kind of rain can last a very long time. long time. Drizzling precipitation falls from stratus (including stratocumulus) clouds.

In addition, precipitation is divided according to their consistency. This is what will be discussed now.

Other types of precipitation

Additionally allocated the following types rainfall:

liquid precipitation. Basic. It was about them that was mentioned above (overlapping, torrential and drizzling types of rain);
solid precipitation. But they fall out, as you know, at a negative temperature. Such precipitation takes on various shapes (snow of the most different forms, hail and so on...);
mixed precipitation. Here the name speaks for itself. An excellent example is a cold freezing rain.

These are the different types of precipitation. And now it is worth making some interesting remarks about their loss.

The shape and size of snowflakes are determined by the temperature in the atmosphere and the strength of the wind. The purest and driest snow on the surface is capable of reflecting about 90% light from the sun's rays.

More intense and larger (in the form of drops) rains occur on small areas. There is a relationship between the size of territories and the amount of precipitation.

The snow cover is able to independently emit thermal energy, which, nevertheless, quickly escapes into the atmosphere.

Clouds with clouds have huge weight. More than 100 thousand km³ of water.

The atmosphere of our planet is constantly in motion - it is not for nothing that it is called the fifth ocean. In its thickness, movements of warm and cold air masses are observed - winds blow at different speeds and directions.

Sometimes the moisture in the atmosphere condenses and falls to the earth's surface in the form of rain or snow. Forecasters call it precipitation.

Scientific definition of precipitation

Atmospheric precipitation in the scientific community, it is customary to call ordinary water, which in liquid (rain) or solid (snow, frost, hail) form falls from the atmosphere to the surface of the Earth.

Precipitation can fall from clouds, which themselves are water condensed into tiny droplets, or form directly in air masses when two atmospheric streams collide with different temperatures.

Precipitation determines climatic features terrain, and also serves as the basis for crop yields. Therefore, meteorologists constantly measure how much precipitation fell in a particular area for a certain period. This information forms the basis of yields, etc.

Precipitation is measured in millimeters of the layer of water that would cover the surface of the earth if the water had not been absorbed and evaporated. On average, 1000 millimeters of precipitation falls per year, but some areas get more and others less.

So, in the Atacama Desert, only 3 mm of precipitation falls per whole year, and in Tutunendo (Colombia) a layer of more than 11.3 meters of rainwater is collected per year.

Precipitation types

Meteorologists distinguish three main types of precipitation - rain, snow and hail. Rain is a drop of water in a liquid state, hail and - in a solid state. However, there are also transitional forms of precipitation:

- rain with snow - a frequent occurrence in autumn, when both snowflakes and drops of water alternately fall from the sky;

- freezing rain - enough rare view precipitation, which is ice balls filled with water. Falling to the ground, they break, the water flows out and immediately freezes, covering the asphalt, trees, roofs of houses, wires, etc. with a layer of ice;

- snow groats - small white balls, resembling groats, falling from the sky when the air temperature is close to zero. The balls consist of ice crystals slightly frozen together and are easily crushed in the fingers.

Precipitation can be torrential, continuous and drizzling.

- Heavy precipitation usually falls suddenly and is characterized by high intensity. They can last from several minutes to several days (in tropical climate), are often accompanied by lightning discharges and sharp gusts of wind.

- Heavy precipitation falls for a long time, several hours or even days in a row. They begin with a weak intensity, gradually increase and then continue without changing the intensity, all the time until the end.

- Drizzling precipitation differs from heavy precipitation in a very small droplet size and in that it falls not only from clouds, but also from fog. Quite often, drizzling precipitation is observed at the beginning and end of extensive precipitation, but can last for several hours or days as an independent phenomenon.

Precipitation formed on the surface of the earth

Some types of precipitation do not fall from above, but are formed directly in the lowest layer of the atmosphere in contact with the earth's surface. In the total amount of precipitation, they occupy a small percentage, but are also taken into account by meteorologists.

- Frost - ice crystals that freeze in the early morning on protruding objects and the ground surface if the night temperature drops below zero.

Dew - drops of water that condense into warm time year as a result of night air cooling. Dew falls on plants, protruding objects, stones, walls of houses, etc.

- Rime - ice crystals that form in winter at a temperature of -10 to -15 degrees on tree branches, wires in the form of fluffy fringe. Appears at night and disappears during the day.

- Icing and ice - freezing of the ice layer on the surface of the earth, trees, walls of buildings, etc. as a result of rapid air cooling during or after sleet and freezing rain.

All types of precipitation are formed as a result of the condensation of water that has evaporated from the surface of the planet. The most powerful "source" of precipitation is the surface of the seas and oceans, land gives no more than 14% of all atmospheric moisture.

It forms the smallest droplets and crystals, which, condensing, form clouds. Under certain conditions, these droplets and crystals begin to grow larger and reach such a size that the ascending currents and air resistance cannot keep them at a height. They fall or are deposited on the earth's surface. Water in liquid or solid state that falls from clouds or settles from the air onto the surface of the earth is called precipitation. Precipitation is classified according to physical condition- liquid (drizzle, rain) and solid (snow, cereals, hail) and by the nature of the fallout - drizzling, overflowing and torrential.

Drizzle - liquid precipitation that falls mainly from stratus clouds or thick. These are very small droplets, the diameter of which is determined by hundredths of a millimeter, they seem to be suspended in the air. The larger ones fall to the ground in the form of drizzle or light rain. The amount of precipitation during drizzle is negligible.

At low temperatures, precipitation similar to drizzle is called small snowflakes or snow grains. During fog it can be observed. Hoarfrost is the deposition of ice on tree branches, wires, etc. in fog and as a result (transition of water vapor from solid state bypassing the liquid phase). Most often, frost forms on the windward side of objects, with light wind and temperatures of -15 ° C and below.

Rain is liquid precipitation in the form of droplets with a diameter of 0.5 mm or more - the predominant form that falls mainly from nimbostratus and cumulonimbus clouds.

Solid precipitation, as well as liquid precipitation, is quite diverse. Snow falls most frequently. Snow is solid precipitation in the form of ice crystals. various shapes falling out of the clouds. It forms at low temperatures. Snow can fall both as separate snowflakes in shape and as snowflakes glued into flakes, which usually form at temperatures close to 0°C, which contributes to the gluing of snowflakes. At the same time, their crystalline basis is preserved. One of the options for snow is snow pellets. Snow groats - solid precipitation falling from clouds in the form of dull white snow-like nuclei of irregular rounded shape ranging in size from 1 to 15 mm. Characteristically, when hitting hard objects, the nuclei of snow pellets bounce off, and do not break. Snow pellets most often fall from cumulonimbus clouds at a temperature of 0°C. Distinguish between snow and ice pellets.

Hail - precipitation that falls in the warm season from powerful, vertically developed cumulonimbus clouds in the form of particles dense ice. Hailstones are different in shape and size - from 5 mm to 15-20 cm. They form in warm weather with powerful ascending currents. Having originated high, the ice crystal in the process of falling increases. Hail fall can sometimes give a cover up to 20-30 cm high on the earth's surface. Intense hail can destroy crops, in some cases lead to the death of animals, cause a lot of mechanical damage to buildings, transport, etc.

The nature of precipitation also varies significantly. Drizzling precipitation is precipitation that falls in the form of drizzle or its solid counterparts (snow grains, fine snow). Most often they are of intramass origin. Severe precipitation is long-term, sufficiently uniform precipitation in the form of rain, snow or drizzle, falling simultaneously over a large area. The precipitation of extensive precipitation continues continuously or with short breaks, sometimes for a significant part of the day or even more than a day. They fall out of nimbostratus and altostratus clouds. Rain means heavy rain, whose intensity, i.e. the amount of precipitation in 1 minute, not below a certain limit. These limits are different. For example, It is raining 5 minutes with an intensity of 50 mm of precipitation per minute, or 30 minutes, and its intensity is 23 mm/min, or it rains for 1 hour with an intensity of 0.20 mm/min. It's all rain. Rainfall is rainfall great intensity, but of short duration. They fall out of cumulonimbus clouds in both liquid and solid form (rain showers, snow showers, etc.). They are characterized by a rapid increase in intensity at the beginning of the fallout, its sharp fluctuations and abrupt cessations. Accompanied by rapid changes, amplification with gusts and squalls, often thunderstorms.

Distribution of precipitation on the surface the globe occurs very unevenly and is zonal in nature. Their number is decreasing, which is mainly due to the atmosphere. In addition, relief and also play an important role in the distribution of precipitation. Warm and humid air masses, meeting with the mountains, rise along their slopes, cool down and give abundant precipitation in the foothill areas. It is on the windward slopes of the mountains that the most wet areas Earth.

The equatorial zone receives the maximum amount of precipitation - up to 2000 mm per year. On the slopes of some mountains falls up to 6000-7000 mm, and, for example, on the slopes () - 10000 mm. A large number of rainfall in equatorial zone due to temperature and, as well as the dominance of ascending air currents that favor the formation of clouds. Between 20 degrees north and south latitudes, almost half of the Earth's precipitation falls.

Between 20 and 40 ° latitude of both hemispheres are dry tropical zones. They are characterized primarily by descending air movements, which do not contribute to the formation of clouds. Most of the world's deserts (, Arabia, Western, etc.) are located in this zone. Particularly poor in precipitation western coasts continents washed by cold currents, where precipitation is negligible or does not fall for several years in a row (Atacama, Namib, desert).

In temperate latitudes, precipitation increases. Here, the average annual precipitation is about 500 mm, but depending on the proximity to the sea, it varies from 100 to 3000 mm. On some coastal ridges, the amount of precipitation reaches 5000 mm (Longitudinal Valley of Chile,). Significant rainfall in temperate latitudes northern hemisphere associated with western transfer.

In the polar regions, the amount of precipitation decreases. This is primarily due low temperatures and downward air movement. The average rainfall is 250-340 mm.

Throughout the Earth, 520 thousand km 3 of precipitation falls annually. Of these, over the oceans - 79% and over land - 21%. The maximum amount of precipitation falls on the Hawaiian Islands (Hawaii,) - 11684 mm / year and in Cherrapunji (, foothills) - 11660 mm / year, which is due to large mountain rises in the path of moist air currents.

A rain gauge and a precipitation gauge are used to measure the amount of precipitation.

A rain gauge is a cylindrical metal bucket with a cross-sectional area of 500 cm2, 40 cm high, which is installed on a wooden pole at a height of 2 m. A diaphragm is inserted into the bucket from above, which does not retain precipitation and prevents their evaporation. The bucket is closed with a special cone-shaped protection (Nifer protection). The precipitates collected over 12 hours are poured into a measuring glass with divisions.

The precipitation gauge of the Tretyakov system is designed in the same way as the rain gauge, but with the difference that its protection consists of 16 separate plates, and the cross-sectional area of \u200b\u200bthe bucket is 200 cm2.