Water that falls on the Earth's surface in the form of rain, snow, hail, or precipitates on objects in the form of condensation like frost or dew, is called atmospheric precipitation. Precipitation can be massive, associated with warm fronts, or torrential, associated with cold fronts.

The appearance of rain is due to the merging of small water droplets in a cloud into larger ones, which, overcoming the force of gravity, fall to the Earth. In the event that the cloud contains small particles of solids (dust grains), the condensation process proceeds faster, since they act as condensation nuclei. At negative temperatures, condensation of water vapor in the cloud leads to snow falling. If snowflakes from the upper layers of the cloud fall into the lower ones with a higher temperature, which contains a large amount of cold water droplets, then the snowflakes combine with water, losing their shape and turning into snowballs up to 3 mm in diameter.

Precipitation formation

Hail is formed in clouds of vertical development, the characteristic features of which are the presence of positive temperatures in the lower layer and negative - in the upper one. In this case, globular snowballs with ascending air currents rise to the upper parts of the cloud with lower temperatures and freeze with the formation of globular ice floes - hailstones. Then, under the influence of gravity, the hailstones fall to the Earth. They usually vary in size and can range in diameter from a pea to a hen's egg.

Types of precipitation

Such types of precipitation as dew, frost, rime, ice, fog are formed in the surface layers of the atmosphere due to condensation of water vapor on objects. Dew appears at higher temperatures, frost and frost at negative temperatures. With an excessive concentration of water vapor in the surface atmospheric layer, fog appears. If fog mixes with dust and dirt in industrial cities, it is called smog.
Measurement of precipitation is carried out according to the thickness of the water layer in millimeters. On our planet, on average, about 1000 mm of precipitation falls per year. To measure the amount of precipitation, a device such as a precipitation gauge is used. For many years, observations have been made of the amount of precipitation in different regions of the planet, due to which the general patterns of their distribution over the earth's surface have been established.

The maximum amount of precipitation is observed in the equatorial zone (up to 2000 mm per year), the minimum - in the tropics and polar regions (200-250 mm per year). In the temperate zone, the average annual rainfall is 500-600 mm per year.

In each climatic zone, irregularities in precipitation are also noted. This is due to the peculiarities of the relief of a certain area and the prevailing direction of the wind. For example, on the western outskirts of the Scandinavian mountain range, 1000 mm falls per year, and on the eastern edges - more than half. Areas of land have been identified where precipitation is almost completely absent. These are the Atacama deserts, the central regions of the Sahara. In these regions, the average annual rainfall is less than 50 mm. A huge amount of precipitation is noted in the southern regions of the Himalayas, in Central Africa (up to 10,000 mm per year).

Thus, the defining features of the climate of a given area are the average monthly, seasonal, average annual precipitation, their distribution over the Earth's surface, and intensity. These features of the climate have a significant impact on many sectors of the human economy, including agriculture.

Related materials:

Atmosphere

Atmosphere pressure

The meaning of the atmosphere

Types of precipitation

There are different classifications for atmospheric precipitation.

Precipitation and their chemical composition

A distinction is made between overburden precipitation, which are associated with warm fronts, and heavy rainfall, which are related to cold fronts.

Precipitation is measured in millimeters - the thickness of the layer of precipitated water. On average, in high latitudes and deserts, about 250 mm falls per year, and in general, about 1000 mm of precipitation per year on the globe.

Measurement of precipitation is essential for any geographic survey. After all, precipitation is one of the most important links in the moisture circulation on the globe.

The defining characteristics for a specific climate are considered to be the average monthly, annual, seasonal and long-term amount of precipitation, their daily and annual variation, their frequency and intensity.

These indicators are extremely important for most branches of the national (agriculture) economy.

Rain is liquid precipitation - in the form of drops from 0.4 to 5-6 mm. Raindrops can leave a trail in the form of a wet spot on a dry object, on the surface of the water - in the form of a diverging circle.

There are different types of rain: icy, hypothermic, and sleet. Both supercooled rain and ice fall at negative air temperatures.

Supercooled rain is characterized by liquid precipitation, the diameter of which reaches 5 mm; ice may form after this type of rain.

And freezing rain is represented by precipitation in a solid state - these are balls of ice, inside which there is frozen water. Snow refers to precipitation that falls in the form of flakes and snow crystals.

Horizontal visibility depends on the intensity of snowfall. Distinguish between sleet and sleet.

The concept of weather and its features

The state of the atmosphere in a particular place at a particular time is called the weather. Weather is the most volatile phenomenon in the environment. It starts raining, then the wind, and after a few hours the sun will shine and the wind will subside.

But even the variability of the weather has its own patterns, despite the fact that a huge number of factors affect the formation of the weather.

The main elements characterizing the weather are the following meteorological indicators: solar radiation, atmospheric pressure, air humidity and temperature, precipitation and wind direction, wind strength and cloudiness.

If we talk about the variability of the weather, then most often it changes in temperate latitudes - in regions with a continental climate. And the most stable weather occurs in polar and equatorial latitudes.

A change in weather is associated with a change of season, that is, changes are periodic, and over time, weather conditions are repeated.

Every day we observe daily changes in the weather - night follows day, and for this reason the weather conditions change.

Climate concept

The climate is called the long-term weather regime. The climate is determined in a specific area - thus, the weather regime must be stable for a specific geographic location.

In other words, the climate can be called the average value of the weather over a long period of time. This period is often over several decades.

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Overhead precipitation

Long-term (from several hours to a day or more) atmospheric precipitation in the form of rain (heavy rain) or snow (heavy snow), falling over a large area with a fairly uniform intensity from stratus and high-stratus clouds on a warm front. Coarse precipitation moisturizes the soil well.

Rain- liquid precipitation in the form of drops with a diameter of 0.5 to 5 mm. Individual raindrops leave a trail on the surface of the water in the form of a diverging circle, and on the surface of dry objects - in the form of a wet spot.

Hypothermic rain- liquid precipitation in the form of drops with a diameter of 0.5 to 5 mm, falling out at a negative air temperature (most often 0 ... -10 °, sometimes up to -15 °) - falling on objects, the drops freeze and ice forms. Freezing rain occurs when falling snowflakes are caught in a layer of warm air deep enough for the snowflakes to completely melt and turn into raindrops. As these droplets continue to fall, they pass a thin layer of cold air above the earth's surface and their temperature drops below freezing. However, the droplets themselves do not freeze, so this phenomenon was called hypothermia (or the formation of "supercooled droplets").

Freezing rain- solid precipitation, falling out at negative air temperatures (most often 0 ... -10 °, sometimes up to -15 °) in the form of hard transparent ice balls with a diameter of 1-3 mm. Formed when rain drops freeze when they fall through the lower layer of air with a negative temperature. There is unfrozen water inside the balls - falling on objects, the balls break into shells, water flows out and ice forms.

Snow- solid precipitation, falling (most often at negative air temperatures) in the form of snow crystals (snowflakes) or flakes. In light snow, horizontal visibility (if there are no other phenomena - haze, fog, etc.) is 4-10 km, with moderate 1-3 km, with heavy snow - less than 1000 m (while the snowfall increases gradually, so that visibility values ​​of 1-2 km or less are observed no earlier than an hour after the beginning of the snowfall). In frosty weather (the air temperature is below -10 ... -15 °), light snow can fall from the cloudy sky. Separately, the phenomenon of wet snow is noted - mixed precipitation falling at a positive air temperature in the form of flakes of melting snow.

Rain with snow- mixed precipitation, falling (most often at a positive air temperature) in the form of a mixture of drops and snowflakes.

Precipitation

If rain and snow falls at a negative air temperature, precipitation particles freeze onto objects and ice forms.

Drizzling precipitation

Drizzle- liquid precipitation in the form of very small droplets (less than 0.5 mm in diameter), as if floating in the air. The dry surface gets wet slowly and evenly. When settling on the surface of the water, it does not form diverging circles on it.

Supercooled drizzle- liquid precipitation in the form of very small drops (with a diameter of less than 0.5 mm), as if floating in the air, falling out at a negative air temperature (most often 0 ... -10 °, sometimes up to -15 °) - settling on objects, the drops freeze and form ice.

Snow grains- solid sediments in the form of small opaque white particles (sticks, grains, grains) with a diameter of less than 2 mm, falling out at negative air temperatures.

Fog- an accumulation of condensation products (drops or crystals, or both), suspended in the air, directly above the earth's surface. Clouding of the air caused by this accumulation. Usually these two meanings of the word fog do not differ. In fog, horizontal visibility is less than 1 km. Otherwise, the haze is called haze.

Heavy rainfall

Shower- short-term atmospheric precipitation, usually in the form of rain (sometimes - wet snow, cereals), characterized by high intensity (up to 100 mm / h). They arise in unstable air masses on a cold front or as a result of convection. Usually heavy rain covers a relatively small area.

Heavy rain- heavy rain.

Heavy snow- heavy snow. It is characterized by sharp fluctuations in horizontal visibility from 6-10 km to 2-4 km (and sometimes up to 500-1000 m, in some cases even 100-200 m) for a period of time from several minutes to half an hour (snow "charges").

Heavy rain with snow- mixed rainfall of a torrential nature, falling (most often at a positive air temperature) in the form of a mixture of drops and snowflakes. If a heavy rain with snow falls at a negative air temperature, precipitation particles freeze onto objects and ice forms.

Snow groats- solid rainfall precipitation, falling at an air temperature of about zero ° and having the appearance of opaque white grains with a diameter of 2-5 mm; grains are fragile, easily crushed by fingers. Often falls before or simultaneously with heavy snow.

Ice croup- solid rainfall precipitation, falling at an air temperature from +5 to + 10 ° in the form of transparent (or translucent) ice grains with a diameter of 1-3 mm; in the center of the grains there is an opaque core. The grains are quite hard (they are crushed by fingers with some effort), when they fall on a hard surface, they bounce off. In some cases, the grains can be covered with a water film (or fall out together with water droplets), and if the air temperature is below zero °, then falling on objects, the grains freeze and ice forms.

Hail- solid precipitation that falls in the warm season (at an air temperature above + 10 °) in the form of pieces of ice of various shapes and sizes: usually the diameter of hailstones is 2-5 mm, but in some cases, individual hailstones reach the size of a pigeon's and even a chicken's egg ( then the hail causes significant damage to vegetation, car surfaces, breaks window panes, etc.). The duration of the hail is usually short - from 1-2 to 10-20 minutes. In most cases, hail is accompanied by heavy rain and thunderstorms.

Ice needles- solid precipitation in the form of the smallest ice crystals floating in the air, formed in frosty weather (air temperature is below -10 ... -15 °). During the day they sparkle in the light of the sun's rays, at night - in the rays of the moon or in the light of lanterns. Quite often, ice needles form beautiful luminous “pillars” at night, extending from the lanterns up into the sky. They are most often observed with a clear or slightly cloudy sky, sometimes falling out of cirrostratus or cirrus clouds.

Many factors determine how much rain or snow falls on the earth's surface. These are temperature, altitude, location of mountain ranges, etc.

Probably the rainiest place in the world is Mount Waialeale in Hawaii, on the island of Kauai. The average annual rainfall here is 1,197 cm. Cherrapunji in India may have the second highest precipitation with an average annual level of 1079 to 1143 cm. Once 381 cm of rain fell in Cherrapunji in 5 days. And in 1861 the amount of precipitation reached 2300 cm!

To make it clearer, let's compare the amount of precipitation in some cities of the world, London receives 61 cm of precipitation per year, Edinburgh about 68 cm, and Cardiff about 76 cm.New York receives about 101 cm of precipitation. Ottawa in Canada gets 86 cm, Madrid - about 43 cm and Paris - 55 cm. So you see what the contrast of Cherrapunji is.

The driest place in the world is probably Arica in Chile. Here the level of precipitation is 0.05 cm per year. The driest place in the USA is Greenland Ranch in Death Valley. There, the average annual rainfall is less than 3.75 cm.

In some large regions of the Earth, heavy rainfall occurs throughout the year. For example, almost every point along the equator receives 152 cm or more of rain each year. The equator is the junction point of two large air currents Everywhere along the equator, air moving down from the north meets air moving up from the south.

There is a major upward movement of hot air mixed with water vapor. As the air rises to colder heights, a large amount of water vapor condenses and falls as rain.

Most of the rain falls on the upwind side of the mountains. The other side, called the leeward side, receives much less rainfall. An example is the Cascade Mountains in California. Westerly winds carrying water vapor move from the Pacific Ocean. Having reached the coast, the air rises along the western slopes of the mountains, cooling.

Precipitation. Scheme and types of precipitation

Cooling causes condensation of water vapor, which falls in the form of rain or snow.

Depending on the nature of cloudiness and the mode of precipitation, two types of their daily variation are distinguished: continental and marine. The continental type is characterized by two maxima: the main one - in the afternoon hours from convective cumulonimbus, and at the equator and from cumulus clouds and insignificant - early in the morning from stratus clouds, between them minimums: at night and before noon.

What is precipitation? What types of precipitation do you know?

In the marine (coastal) type, there is one maximum precipitation at night (due to unstable air stratification and convection) and one minimum during the day. These types of daily variation of precipitation are observed throughout the year in the hot zone, and in temperate zones are possible only in summer.

The annual course of precipitation, i.e., their change by months during the year, is very different in different places on the Earth. It depends on many factors: the radiation regime, the general circulation of the atmosphere, the specific physical and geographical situation, etc. It is possible to outline several basic types of the annual course of precipitation and express them in the form of bar diagrams (Fig. 47).

Fig. 47. Types of the annual course of precipitation on the example of the Northern Hemisphere

Equatorial type - heavy rainfall falls fairly evenly throughout the year, there are no dry months, there are two small maxima - in April and October, after the equinox days, and two small minimums in July and January, after the solstice days.

Monsoon type - maximum precipitation in summer, minimum - in winter. It is characteristic of subequatorial latitudes, where the annual course of precipitation is very sharply expressed due to the dryness of winter, as well as the eastern coasts of the continents in subtropical and temperate latitudes. However, the annual amplitude of precipitation is somewhat smoothed here, especially in the subtropics, where frontal rains also fall in winter. At the same time, the annual amount of precipitation gradually decreases from the subequatorial to the temperate zone.

Mediterranean type - maximum precipitation in winter due to active frontal activity, minimum - in summer. It is observed in subtropical latitudes on the western coasts and inland.

In temperate latitudes, two main types of annual precipitation are distinguished: continental and marine. The continental (inland) type is distinguished by the fact that in summer it receives two to three times more precipitation than in winter, due to frontal and convective precipitation.

Marine type - precipitation is evenly distributed throughout the year with a slight maximum in autumn and winter. Their number is greater than in the previous type.

The Mediterranean and temperate continental types are characterized by a decrease in the total amount of precipitation as we move inland.

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Precipitation is one of the meteorological elements strongly dependent on a number of local landscape features.

Let us try, however, to trace what conditions influence their distribution.

First of all, it is necessary to note the value of the air temperature. Temperature decreases from the equator to the poles; consequently, both the evaporation rate and the moisture holding capacity of the air decrease in the same direction. In cold regions, evaporation is small, and cold air is not able to dissolve a lot of water vapor; therefore, during condensation, a large amount of precipitation cannot be released from it. In warm areas, strong evaporation and high moisture capacity of the air lead to abundant precipitation during condensation of water vapor. Thus, on Earth, a regularity should inevitably manifest itself, which consists in the fact that in warm regions there is especially a lot of precipitation, in cold regions there are few of them. This pattern actually manifests itself, but, like other phenomena in nature, it is complicated, and in some places it is completely obscured by a number of other influences, and above all by the circulation of the atmosphere, the nature of the distribution of land and sea, relief, height above ocean level and sea currents.

Knowing the conditions necessary for the condensation of water vapor, it is possible to predict how the circulation of the atmosphere affects the distribution of precipitation. Since air is a carrier of moisture, and its movement covers vast spaces on Earth, this inevitably leads to a smoothing out of differences in the amount of precipitation caused by the distribution of temperatures in areas where the air experiences uplifts (above the equator, in cyclones, on the windward slopes of mountain ranges). an environment favorable for precipitation is created, and all other factors become subordinate. In the same places where descending air movements prevail (at subtropical highs, in anticyclones in general, in the area of ​​trade winds, on leeward slopes of mountains, etc.), precipitation is much less.

It is generally accepted that the amount of precipitation in a given area is highly dependent on its proximity to the sea or distance from the sea. In fact, many examples are known when very dry areas of the Earth are located on the ocean coasts and, on the contrary, far from the sea, inside the country (as, for example, on the eastern slope of the Andes in the upper Amazon), a huge amount of precipitation falls. It is not so much a matter of distance from the sea as of the nature of the circulation of the atmosphere and the structure of the surface, that is, in the absence or presence of mountain ranges that interfere with the movement of air masses carrying moisture. During the southwestern monsoon in India, air masses pass over the Thar desert, not irrigating it with rains, since the flat relief does not impede the movement of air, and the heated desert has a rather drying effect on the air masses.

Types of precipitation.

But the same monsoon on the windward slope of the Western Ghats, not to mention the southern slopes of the Himalayas, leaves a huge amount of moisture.

The need to separate orographic sediments into a special type indicates the extremely large role of the structure of the earth's surface in the distribution of sediments. True, in this case, as in all the others, the relief is important not only in itself, as a mechanical obstacle, but in combination with the absolute height and circulation of the atmosphere.

The penetration of warm sea currents into high latitudes contributes to the formation of atmospheric precipitation due to the fact that cyclonic circulation of the atmosphere is associated with warm currents. Cold currents have the opposite effect, since spurs of high pressure usually develop above them.

Of course, none of these factors affects the distribution of precipitation independently of others. In each case, atmospheric moisture loss is regulated by a complex and sometimes contradictory interaction of both general and local agents. However, if we ignore the details, the main conditions that determine the placement of precipitation in the landscape envelope, it is nevertheless necessary to include temperature, general atmospheric circulation and relief.

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The main factor that has a significant impact on the progress of the flora and fauna of the planet Earth is the presence of a climate favorable for the development of life (temperature, humidity, various types of precipitation).

From this list, it is atmospheric phenomena that create numerous climatic zones, which, in turn, are distinguished by a variety of life forms.

All precipitation is inextricably linked with the water cycle in nature - this includes all phenomena that are formed on the basis of the physicochemical properties of water and its ability to be in three states of aggregation - liquid, solid and vapor (3 types of precipitation).

At school, this topic is held in grade 2 on the subject "The World Around".

What is precipitation

It is customary to give a strict definition of atmospheric precipitation in geography as follows. This term refers to such phenomena that occur in the Earth's atmosphere, which are based on the concentration of water in the air layer, and are also associated with the transition of water dispersion into various states of aggregation and fallout to the surface of the planet.

The main classification of precipitation is separation by temperature of atmospheric fronts:

  • oversized- associated with warm air currents;
  • showers- associated with cold air masses.

To account for the amount of precipitation that falls on the Earth's surface in a certain region, meteorologists use special equipment - rain gauges, which provide data measured in the thickness of a layer of liquid water that falls on a solid surface. Units of measurement are millimeters per year.

Natural precipitation plays a key role in the formation of the earth's climate and forms the circulation of water in nature.

Types of precipitation

It is possible to conditionally divide the types of precipitation on the basis of the aggregate state of water in which it falls on the Earth. In principle, this is possible in only two versions - solid and liquid form.

Based on this, the classification is as follows:

  • liquid- (rain and dew);
  • solid- (snow, hail and frost).

Let's figure out what each type of such precipitation is.

The most common type of precipitation is rain(refers to convective precipitation). This phenomenon is formed under the influence of the sun's radiant energy, which heats the moisture on the Earth's surface and evaporates it.

Getting into the upper layers of the atmosphere, which are noticeably colder, water condenses, forming an accumulation of tiny droplets. As soon as the amount of condensate reaches a large mass, then water is poured onto the ground in the form of a heavy rain.

The types of rain are classified according to the size of the droplets, which, in turn, is related to the flow and temperature of the air.

A kind of rain is formed like this - if the air is warm, then it forms larger drops, and if it is cold, then a drizzling light rain can be observed (supercooled rain). When the temperature drops, it will rain and snow.

Another condensation-related process is dew loss. This physical phenomenon is based on the fact that in a certain volume of air there can be a strictly defined amount of steam at a given temperature.

Until the maximum volume of steam is reached, condensation does not occur, but as soon as the amount exceeds the required value, the excess falls into a liquid state. We can observe this in the early morning on the street, looking at dew, flowers and other solid objects.

Another common type of precipitation is snow. In principle, its formation is similar to the formation of rain, however, rain differs from snow in that when it falls to the ground, drops are significantly cooled by air jets, which have a negative temperature, and microscopic ice crystals are formed.

Since the process of formation of snowflakes occurs in the air and under the influence of different temperatures, this causes a large number of forms and crystals of snowflakes.

If the temperature is very low, then heavy snow is formed, if closer to zero, then heavy snow. Wet snow forms at temperatures slightly above freezing.

One of the dangerous atmospheric phenomena is hail. Its formation occurs mainly in summer, when heated air currents carry vaporous moisture into the upper atmosphere, where, supercooling, the water freezes, forming ice pieces.

They do not have time to melt when flying to the earth's surface and are often the reason for the destruction of crops or damage to buildings.

Condensation of water from steam is also possible in winter. This is mainly due to the very low relative humidity of the air.

At the same time, given the negative temperature, the condensed moisture immediately freezes on hard surfaces, forming frost.

Types of precipitation by seasons

A characteristic based on the seasonality of precipitation is often used.

So, there are:

  • precipitation falling mainly during the warm season- rain, drizzle (rain subtype), dew, hail;
  • precipitation that occurs during the cold season- snow, groats (a subspecies of snow), hoarfrost, rime, ice.

Types of precipitation by height of formation

More accurate is the classification, which takes into account the height at which the condensate was transformed into one of the types of precipitation:

  • precipitation that forms in the upper and middle layers of the atmosphere include rain, drizzle, hail, cereal and snow - falling out of clouds;
  • precipitation that forms in the immediate vicinity of the earth's surface (orographic precipitation) includes mainly condensation phenomena (examples are dew, frost, rime and ice) - falling out of the air.

How precipitation is measured

Often in the weather forecast, you can hear that 2 millimeters of precipitation fell per day. Such data are determined by meteorologists and forecasters at meteorological stations using special equipment - rain gauges.

These are graduated buckets (on which the conventional signs are applied), made in a certain standard size, which are installed on the street.

Every day, in the time interval from 9-00 to 21-00 (the time is taken according to the GMT 0 time zone), the meteorologist collects all the moisture that accumulates in the bucket and pours it into a measuring cylinder (the cylinder divisions are in mm).

The obtained values ​​are entered into the accounting log, forming a precipitation table. If the precipitation was solid, then it is allowed to melt it.

To build a visual picture, points with the measured amount of precipitation are indicated on the map. These points are connected in a diagram with lines - isohyets, and the space is painted over with the colors of precipitation with increasing intensity.

How precipitation affects aviation

There are a number of very important atmospheric factors that impede the operation of aviation. First of all, this is related to ensuring flight safety.

The main ones are:

  1. First of all, this is a deterioration in visibility for aircraft pilots. Reduced visibility in heavy rain or snow storm occurs up to 1.5-2 km, which makes it difficult to visually control the course.
  2. During takeoff or landing, condensation of moisture on glass or optical reflectors can lead to distorted perception of information by the pilot.
  3. A large amount of water fine dust, if it enters the engine, can impede and disrupt its operation.
  4. When the aerodynamic elements of the aircraft (wings, steering elements) are iced, there is a loss of flight performance.
  5. When a significant amount of precipitation falls, contact with the runway surface becomes difficult.

Thus, all precipitation in relation to aviation is extremely unfavorable.

Precipitation is a key factor contributing to the formation of the Earth's climate and geographic zones. The conditional division is carried out depending on the seasonality, however, it should be remembered that combinations can occur in the off-season. Also, precipitation is the most important element of water circulation on the planet.

What is water vapor? What properties does it possess?

Water vapor is the gaseous state of water. Has no color, taste or smell. Contained in the troposphere. Formed by water molecules during evaporation. When cooled, water vapor turns into water droplets.

What seasons of the year does it rain in your area? What kind of snowfall?

It rains in summer, autumn, spring. Snowfalls - winter, late autumn, early spring.

Using Figure 119, compare the average annual precipitation in Algeria and in Vladivostok. Is precipitation equally distributed over the months?

The annual precipitation in Algeria and Vladivostok is practically the same - 712 and 685 mm, respectively. However, their distribution throughout the year is different. In Algeria, maximum precipitation occurs in late autumn and winter. The minimum is for the summer months. In Vladivostok, most of the precipitation falls in summer and early autumn, at least in winter.

Consider the picture and talk about the alternation of belts with different annual rainfall.

In the distribution of precipitation in general, changes are observed in the direction from the equator to the poles. In a wide strip along the equator, their greatest number falls - over 2000 mm per year. In tropical latitudes, precipitation is very little - on average 250-300 mm, and in temperate latitudes, it again becomes more. With further approach to the poles, the amount of precipitation decreases again to 250 mm per year or less.

Questions and tasks

1. How is precipitation formed?

Atmospheric precipitation is water that has fallen to the ground from clouds (rain, snow, hail) or directly from the air (dew, frost, rime). Clouds are made up of tiny water droplets and ice crystals. They are so small that they are held in by currents of air and do not fall to the ground. But droplets and snowflakes can merge with each other. Then they increase in size, become heavy and fall to the ground in the form of precipitation.

2. Name the types of precipitation.

Precipitation is liquid (rain), solid (snow, hail, grains) and mixed (snow and rain)

3. Why does the collision of warm and cold air lead to precipitation?

When colliding with cold air, warm air displaced by heavy cold air rises and begins to cool. Water vapor condenses in warm air. This leads to the formation of clouds and precipitation.

4. Why doesn't precipitation always fall on cloudy weather?

Precipitation falls only if the air is saturated with moisture.

5. How can you explain that there is a lot of precipitation near the equator, and very little in the regions of the poles?

A large amount of precipitation falls near the equator, because due to high temperatures, a large amount of moisture evaporates. The air quickly becomes saturated and precipitation falls. At the poles, low air temperatures prevent evaporation.

6. What amount of precipitation falls per year in your area?

In the European part of Russia, on average, about 500 mm will fall out per year.

PRECIPITATION

PRECIPITATION, in meteorology - all forms of water, liquid or solid, falling from the atmosphere to the earth. Precipitation differs from CLOUDS, MIST, DEW and FROST in that it falls and reaches the ground. Includes rain, drizzle, SNOW and hail. Measured by the thickness of the layer of precipitated water and are expressed in millimeters. Precipitation occurs due to the CONDENSATION of cloud water vapor into small water particles, which merge into large droplets with a diameter of about 7 mm. Precipitation also forms from melting ice crystals in clouds. Drizzle consists of very small droplets, and snow is made of ice crystals, mainly in the form of hexagonal plates and six-rayed stars. Groats is formed when raindrops freeze and turn into small balls of ice, and hail - when concentric layers of ice in cumulonimbus clouds freeze up, forming rather large rounded pieces of irregular shape, from 0.5 to 10 cm in diameter.

Precipitation. Thin clouds and clouds in the tropics do not reach freezing height, therefore ice crystals do not form in them (A). Instead, a larger-than-normal water particle in the cloud can combine with several million other water particles to achieve the size of a raindrop. Electric charges can promote the pooling of water particles if they have opposite charges. Some droplets break into pieces, forming water particles large enough to cause a chain reaction, generating a stream of raindrops. Most mid-latitude rains, however, are the result of falling snowflakes that melt before they reach land (B). Many millions of small water particles and ice crystals must combine to form one drop or snowflake heavy enough to fall from the cloud to the ground. However, a snowflake can grow out of ice crystals in as little as 20 minutes. In order for large hailstones to form, strong air flows (C) are required (hailstones with a diameter of 30 mm are formed at an air flow rate of 100 km / h). Vortex air currents during a thunderstorm transform frozen water particles into initial hail. Abundant supercooled moist water particles easily freeze to its surface. The air currents are thrown from side to side, as a result of which numerous dense layers of ice, which can be transparent or white, are concentrated on it. An opaque layer forms when air bubbles, and sometimes ice crystals, enter the hailstone during rapid freezing in the cold upper layers of the cloud. Transparent layers form in the warmer lower tiers of the cloud, where the water freezes much more slowly. The hailstones can be up to 25 or more layers (D), with the last - the transparent layer of ice, often the thickest - formed when the hail falls through the moist and warm lower the edge of the cloud. The largest city was registered on September 3, 1970 in Coffyville, Kansas. Its diameter was 190 mm and its weight was 766 g.


Scientific and technical encyclopedic dictionary.

Synonyms:

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    Modern encyclopedia

    Atmospheric water in a liquid or solid state (rain, snow, grains, ground hydrometeors, etc.), falling out of clouds or deposited from the air on the earth's surface and on objects. Precipitation is measured by the thickness of the precipitated water layer in mm. IN… … Big Encyclopedic Dictionary

    Krupa, snow, drizzle, hydrometeor, lotions, rain Dictionary of Russian synonyms. precipitation n., number of synonyms: 8 hydrometeor (6) ... Synonym dictionary

    Precipitation- atmospheric, see Hydrometeors. Ecological encyclopedic dictionary. Chisinau: Main editorial office of the Moldavian Soviet Encyclopedia. I.I. Grandpa. 1989. Precipitation water coming from the atmosphere to the surface of the earth (in liquid or solid ... Ecological Dictionary

    Precipitation- atmospheric, water in a liquid or solid state, falling out of clouds (rain, snow, grains, hail) or settling on the earth's surface and objects (dew, frost, frost) as a result of condensation of water vapor in the air. Precipitation is measured ... ... Illustrated Encyclopedic Dictionary

    In geology, loose formations deposited in a suitable environment as a result of physical, chemical and biological processes ... Geological terms

    Precipitation, ov. Atmospheric moisture falling to the ground in the form of rain, snow. Abundant, weak o. No precipitation today (no rain, no snow). | adj. sedimentary, oh, oh. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Ozhegov's Explanatory Dictionary

    - (meteor.). This name is customary to denote the moisture that falls on the surface of the earth, being separated from the air or from the soil in a liquid or solid droplet form. Such a release of moisture occurs every time when water vapor, constantly ... ... Encyclopedia of Brockhaus and Efron

    1) atmospheric water in a liquid or solid state, falling out of clouds or deposited from the air on the surface of the earth and on objects. O. falls from the clouds in the form of rain, drizzle, snow, sleet, snow and ice grains, snow grains, ... ... Emergency Dictionary

    PRECIPITATION- meteorological, liquid and solid bodies released from the air to the surface of soil and solid objects due to the thickening of water vapor contained in the atmosphere. If O. fall from a certain height, then hail and snow are obtained for rain; if they… … Great medical encyclopedia

Books

  • Precipitation and Thunderstorms from December 1870 to November 1871, A. Voeikov. Reproduced in the original author's spelling of the 1875 edition (St. Petersburg publishing house). IN…

In meteorology, precipitation is subdivided into the following types:

Rain- liquid droplet precipitation (droplet diameter is usually 0.5 - 0.7 mm, sometimes more) .

Drizzle- sediments consisting of small homogeneous cough (diameter 0.05-0.5 mm), falling imperceptibly.

Freezing rain- precipitation in the form of ice balls (diameter from 1 to 3 mm).

Hail- sediments with pieces of ice of various sizes and shapes (diameter from 4-5 to 50 mm, sometimes more).

Snow- solid precipitates in the form of crystals, stars or flakes.

Wet snow- precipitation in the form of melting snow and rain. Snow pellets - precipitation in the form of white round snow balls (diameter from 2 to 5 mm).

Snow grains- small snow grains (diameter less than 1 cm).

Ice needles- suspended thin ice sticks, sparkling in the sunlight of a frosty day. "

By the nature of precipitation, they are divided into three types: overburden, heavy rainfall and drizzling (drizzle).

Overhead precipitation fall out of stratus and high-stratus clouds for a long time over a large area. Their intensity ranges from 0.5 to 1 mm / min. Heavy rainfall can fall in the form of rain and snow (sometimes wet).

Heavy rainfall fall out of cumulonimbus clouds in a confined space in large numbers and in a short period of time. Their intensity is from 1 to 3.5 mm / min and more (there were showers in the Hawaiian Islands - 21.5 aphids min). Heavy rainfall is often accompanied by thunderstorms and squalls. As well as overburden, heavy rainfall can fall in the form of rain and snow. In the latter case, they are called "snow charges".

Drizzle (drizzle) are small droplets (snowflakes) with a very low falling speed. Dropped by stratus clouds or fog. Their intensity is insignificant (less than 0.5 mm / min).

Snowstorm is a special form of precipitation. In a blizzard, the wind carries snow along the earth's surface over long distances. A blizzard occurs when the wind is strong enough. There are three types of blizzards: general (with heavy snowfall and wind from 7 m / sec), downstream (without snowfall, with a wind of 10-12 m / sec) and drifting snow (no snowfall, with wind 6 m / sec and more).

Measurement of precipitation

The amount of precipitation is measured rain gauge, which is a bucket closed with a lattice, installed on a pole and protected from the wind by a special device. The deposited precipitation is poured into a beaker and measured. Precipitation is expressed as the height of the water layer in millimeters, formed as a result of precipitation on a horizontal surface in the absence of evaporation, seepage and runoff.

Usually taken into account amount of precipitation per day, as well as monthly, seasonal and annual precipitation. Precipitation intensity represents the amount of precipitation in millimeters that falls in one minute (mm / min). The amount of snowfall is determined by measuring the height of the snow cover in centimeters from the ground using snow gauge with centimeter divisions.

Impact of precipitation on aviation operations

Precipitation has an extremely adverse effect on aviation operations, namely:

In precipitation, visibility from the aircraft is impaired. In light to moderate rain or light snow, horizontal visibility deteriorates to 4-2 km, and at high flight speed - up to 1-2 km. In heavy rain, as well as in moderate and heavy snowfall, visibility sharply deteriorates to several tens of meters.

In addition, the water film on the glass of the cockpit canopy causes optical distortion of visible objects, which is dangerous during takeoff and especially during landing.

In flight in the precipitation zone, in addition to the deterioration of visibility, there is a decrease in the height of the clouds.

In heavy rain, the speed indicator may be underestimated, sometimes up to 100 km / h. This is due to the partial blockage of the air pressure receiver hole by water drops.

Heavy rainfall can enter the engine and impede or disrupt engine operation.

In flight in the area of ​​supercooled rain, there is a very dangerous intensive icing of the aircraft.

Precipitation has a significant impact on the condition and operation of aerodromes:

Precipitation on the runway reduces the coefficient of friction, which impairs runway controllability and increases the take-off and roll-off distances.

Water, snow, slush thrown by the bow or main wheels can be sucked into the engines, causing damage to their structure or loss of thrust, possibly clogging of small air intakes, slots in the controls, mechanization, chassis, various doors and hatches, SHS receivers, which leads to obstruction or damage to the relevant aircraft systems.

Prolonged or heavy rains can lead to the soaking of unpaved airfields.

The snow cover formed at the airfield due to snowfalls requires special work on its cleaning or rolling in order to ensure normal flights.