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 apart, 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 hailstones. 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 are concentrated on it, which can be transparent or white. An opaque layer forms when air bubbles, and sometimes ice crystals, enter a hailstorm during rapid freezing in the cold upper tiers 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), and the last - the transparent layer of ice, often the thickest - is 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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    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. V… … 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 earth's surface (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 that falls 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. This release of moisture occurs every time 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). V…

Ministry of Education and Science

Russian Federation

Federal Agency for Education

Federal state budgetary educational institution

Higher professional education

"Chuvash State University named after I. N. Ulyanov"

Faculty of History and Geography

Department of Physical Geography and Geomorphology named after E.A. Archikova


Course work

"Atmospheric precipitation and their chemical composition"


Performed

student gr. IGF 22-12

Grigorieva O.V.

Supervisor:

Art. avenue Shlemp OA


Cheboksary 2012


Introduction

1.1 Types of precipitation

2.1 Precipitation falling on the earth's surface

Conclusion

Bibliography

Application

Introduction


The relevance of the study of atmospheric precipitation lies in the fact that precipitation is the main water-balance component of all types of natural waters and the main source of natural resources of groundwater. Atmospheric fallout constantly affects all components of the environment, is an unavoidable factor, and therefore, in the theory of risk, it belongs to the highest category.

Atmospheric precipitation as products of condensation and sublimation of water vapor in the atmosphere is an important climatic parameter that determines the mode of humidification of the territory. For the occurrence of atmospheric precipitation, it is necessary to have a moist air mass, ascending movements and condensation nuclei.

Therefore, by the amount and intensity of precipitation it is possible to indirectly judge the nature of vertical movements in the atmosphere, which are most difficult to assess in the energy cycle of the atmosphere.

The aim of the work is to study atmospheric precipitation and their chemical composition.

To achieve this goal, it is necessary to solve the following tasks:

.Consider the concept of atmospheric precipitation;

2.Explain the distribution of daily and annual precipitation;

.Consider the classification of atmospheric precipitation;

.Find out what chemical components are included in the composition of precipitation

Work structure. The course work consists of an introduction, six chapters, a conclusion, a bibliography and an application.

precipitation chemical composition

1. Precipitation and their types


Precipitation refers to moisture that has fallen to the surface from the atmosphere in the form of rain, drizzle, cereal, snow, hail. Precipitation falls from clouds, but not every cloud gives precipitation. The formation of precipitation from the cloud is due to the enlargement of the droplets to a size that can overcome the upward currents and air resistance. The enlargement of droplets occurs due to the merging of droplets, evaporation of moisture from the surface of droplets (crystals) and condensation of water vapor on others. Precipitation is one of the links in the moisture cycle on Earth.

The main condition for the formation of atmospheric precipitation is the cooling of warm air, leading to condensation of the vapor contained in it.


.1 Types of precipitation


Overburden precipitation - uniform, long-lasting, falling from stratus clouds;

Heavy rainfall - characterized by a rapid change in intensity and short duration. They fall from cumulonimbus clouds as rain, often with hail.

Drizzle - in the form of drizzle falls from stratus and stratocumulus clouds.

By origin, they are distinguished:

Convective precipitation is typical for the hot zone, where heating and evaporation are intense, but in summer they often occur in the temperate zone.

Frontal precipitation is formed when two air masses with different temperatures and other physical properties meet, fall out of the warmer air that forms cyclonic vortices, typical for temperate and cold zones.

Orographic precipitation falls on the windward slopes of mountains, especially high ones. They are abundant if the air comes from the warm sea and has a high absolute and relative humidity. (see Appendix 4)


2. Classification of atmospheric precipitation


.1 Precipitation falling on the earth's surface


They are characterized by monotonicity of dropout without significant fluctuations in intensity. They start and stop gradually. The duration of continuous precipitation is usually several hours (and sometimes 1-2 days), but in some cases light precipitation can last half an hour or an hour. They usually fall out of stratus or altostratus clouds; moreover, in most cases the cloudiness is continuous (10 points) and only occasionally significant (7-9 points, usually at the beginning or end of the precipitation period). Sometimes weak short-term (half an hour - an hour) heavy precipitation is noted from stratus, stratocumulus, altocumulus clouds, while the amount of clouds is 7-10 points. In frosty weather (the air temperature is below? 10 ... -15 °), light snow can fall from the cloudy sky.

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.

Supercooled rain - liquid precipitation in the form of drops with a diameter of 0.5 to 5 mm, falling out at negative air temperatures (most often 0 ... -10 °, sometimes up to? 15 °) - falling on objects, the drops freeze and ice forms.

Freezing rain- solid precipitation, falling out at negative air temperatures (most often 0 ... -10 °, sometimes up to? 15 °) in the form of solid transparent ice balls with a diameter of 1-3 mm. 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 positive air temperatures) in the form of a mixture of drops and snowflakes. If rain and snow falls at a negative air temperature, precipitation particles freeze onto objects and ice forms.

Drizzling precipitation

They are characterized by low intensity, monotony of loss without changing the intensity; start and stop gradually. The duration of continuous shedding is usually several hours (and sometimes 1-2 days). Fall out of stratus clouds or fog; moreover, in most cases the cloudiness is continuous (10 points) and only occasionally significant (7-9 points, usually at the beginning or end of the precipitation period). Often accompanied by reduced visibility (haze, fog).

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. Having settled 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 ice forms.

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.

Heavy rainfall

They are characterized by the suddenness of the beginning and end of the loss, a sharp change in intensity. The duration of continuous shedding is usually from several minutes to 1-2 hours (sometimes several hours, in the tropics - up to 1-2 days). They are often accompanied by a thunderstorm and a short-term increase in wind (squall). Fall out of cumulonimbus clouds, while the amount of clouds can be both significant (7-10 points) and small (4-6 points, and in some cases even 2-3 points). The main sign of heavy rainfall is not their high intensity (heavy rainfall can be weak), but the very fact of falling from convective (most often cumulonimbus) clouds, which determines the fluctuations in precipitation intensity. In hot weather, light rain showers can fall from powerful cumulus clouds, and sometimes (very weak rain showers) even from medium cumulus clouds.

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 0 ° and having the appearance of opaque white grains with a diameter of 2-5 mm; grains are fragile, easily crushed with 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 0 °, then falling on objects, the grains freeze and ice forms.

Hail- solid precipitation that falls in the warm season (at air temperatures above + 10 °) in the form of pieces of ice of various shapes and sizes: usually the diameter of the 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 to 20 minutes. In most cases, hail is accompanied by heavy rain and thunderstorms.

Unclassified precipitation

Ice needles- solid precipitation in the form of the smallest ice crystals floating in the air, formed in frosty weather (air temperature below? 10 ... -15 °). During the day they sparkle in the light of the rays of the sun, 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.

Zolation- precipitation in the form of rare and large (up to 3 cm) water bubbles. A rare phenomenon that occurs during light thunderstorms.

Precipitation formed on the surface of the earth and on objects

Dew -water droplets formed on the surface of the earth, plants, objects, roofs of buildings and cars as a result of condensation of water vapor in the air at positive air and soil temperatures, little cloudy skies and weak winds. Most often observed at night and early morning hours, may be accompanied by haze or fog. Abundant dew can cause a measurable amount of precipitation (up to 0.5 mm per night), water runoff from roofs to the ground.

Frost- white crystalline sediment formed on the surface of the earth, grass, objects, roofs of buildings and cars, snow cover as a result of desublimation of water vapor contained in the air at negative soil temperatures, little cloudy skies and weak winds. Observed in the evening, night and morning hours, may be accompanied by haze or fog. In fact, this is an analogue of dew, which forms at negative temperatures. On tree branches, wires, frost is deposited weakly (unlike rime) - on a wire of an ice machine (diameter 5 mm), the thickness of frost deposits does not exceed 3 mm.

Crystal rime- a white crystalline precipitate, consisting of small fine-structured shiny ice particles, formed as a result of desublimation of water vapor contained in the air on tree branches and wires in the form of fluffy garlands (easily crumbling when shaken). It is observed in low-cloud (clear, or upper and middle tier clouds, or broken-layered) frosty weather (air temperature below? 10 ... -15 °), with haze or fog (and sometimes without them) with weak wind or calm. Rime deposition occurs, as a rule, for several hours at night, during the day it gradually crumbles under the influence of sunlight, but in cloudy weather and in the shade it can persist throughout the day. On the surface of objects, roofs of buildings and cars, frost is deposited very little (unlike frost). However, frost is often accompanied by frost.

Grainy rime- white loose snow-like sediment formed as a result of the settling of small droplets of supercooled fog on tree branches and wires in cloudy foggy weather (at any time of the day) at air temperatures from 0 to −10 ° and moderate or strong winds. With the enlargement of fog droplets, it can turn into ice, and with a decrease in air temperature, combined with a weakening of the wind and a decrease in the amount of cloudiness at night, into crystalline frost. The growth of granular hoarfrost lasts as long as fog and wind lasts (usually several hours, and sometimes several days). Preservation of the deposited granular hoarfrost can last for several days.

Ice- a layer of dense glassy ice (smooth or slightly bumpy), formed on plants, wires, objects, the surface of the earth, as a result of freezing of precipitation particles (supercooled drizzle, supercooled rain, freezing rain, ice grains, sometimes rain and snow) in contact with the surface having a negative temperature. It is observed at an air temperature most often from 0 to –10 ° (sometimes up to –15 °), and with a sharp warming (when the earth and objects still maintain a negative temperature) - at an air temperature of 0 ... + 3 °. It greatly impedes the movement of people, animals, transport, can lead to wire breaks and breaking off tree branches (and sometimes to a massive fall of trees and masts of power lines). The accumulation of ice lasts as long as supercooled precipitation lasts (usually several hours, and sometimes with drizzle and fog - several days). Preservation of the deposited ice can last for several days.

Ice- a layer of lumpy ice or icy snow formed on the surface of the earth due to the freezing of melt water, when, after a thaw, the temperature of the air and soil decreases (transition to negative temperatures). Unlike ice, ice is observed only on the earth's surface, most often on roads, sidewalks and paths. The preservation of the formed ice cover can last for many days in a row until it is covered from above with freshly fallen snow cover or melts completely as a result of an intense increase in air and soil temperature.

3. Chemical composition of atmospheric precipitation


Prevailing in atmospheric precipitation: НСО3-, SO42-, Cl-, Ca2 +, Mg2 +, Na +. They enter the sediments due to the dissolution of air gases, bringing salt from the sea with the wind, dissolution of salts and dust of continental origin, volcanic exhalations and other sources. The total amount of dissolved substances, as a rule, does not exceed 100 mg / l, often it is less than 50 mg / l. These are ultra-fresh waters, but in some places the mineralization of sediments rises to 500 mg / l and more. The pH of rainwater is usually 5-7. Rainwater also contains some hydrogen peroxide.

As a result of the physical evaporation of salts, as well as the splashing of sea water during waves in the surf zone and the subsequent evaporation of water droplets, the sea air is enriched with elements of sea water, and the winds blowing from the sea bring sea salts to the land. Most of the Cl, Li, Na, Rв, Cs, B, I in river waters are probably of marine origin. These are the so-called "cyclic salts", which fall on land with atmospheric precipitation and then again enter the ocean with runoff. According to V.D. Korzh and V.S. Sayenko, on average, up to 15% of river runoff salts are brought into rivers from the ocean through the atmosphere.

In atmospheric precipitation of the sea coasts, the Cl - content can exceed 100 mg / l (in the inland regions, 2-3 mg / l). However, already at a distance of several tens of kilometers from the coast, the content of sea salts in atmospheric precipitation sharply decreases to 1-3 mg / l.

In the atmospheric precipitation of the inland regions, not Cl - and Na +, but - SO42-, Ca2 + prevail. In the humid inland areas, the mineralization of sediments is low, about 20-30 mg / l, they are dominated by HCO3 - and Ca2 + ions of continental origin.

4. Regularities of distribution of atmospheric precipitation


The following regularities in the distribution of atmospheric precipitation are noted. Most often, precipitation falls over the ocean. Over continents, the degree of sediment mineralization is determined by the climatic factor. Maximum sediment mineralization is typical for desert landscapes. Technogenic processes increase the mineralization of precipitation over large industrial centers and change the properties of atmospheric water. However, it is not always possible to determine the content of incoming salts by the amount of precipitation. In humid tropical forests, where there is little dust in the air, atmospheric precipitation has a lower mineralization, precipitation in the taiga zone is higher. However, the total amount of salts supplied with atmospheric precipitation will be higher in the humid tropics than in the taiga, since the amount of precipitation is 2-3 times greater.

Within the continent, by natural zones, the deposition of salts depends on the amount of precipitation, air humidity, and dustiness of the atmosphere.

In each landscape zone, the mineralization of atmospheric precipitation depends on the seasons: in winter, spring and in the humid summer period, the mineralization of precipitation is lower than in dry one. The movement of the air mass formed over the ocean inland leads to its gradual depletion in chemical elements as precipitation falls. With precipitation on the sea coasts, 47 mg / l of salts fall out; within the continent, at a distance of 200 km from the coast, the amount of precipitated salts decreases to 28 mg / l.

M.A. Glazovskaya proposed two coefficients for characterizing atmospheric migration: the coefficient of atmogeochemical activity (CA) and the coefficient of hydrogeochemical activity (CA). CA is the ratio of the amount of an element supplied with precipitation per year to their amount consumed by plants per year. KI is the ratio of the number of elements carried out by the ionic runoff per year to their amount arriving with atmospheric precipitation.


5. Distribution of daily and annual precipitation


The daily course of precipitation coincides with the daily course of cloudiness. There are two types of daily variation of precipitation - continental and marine (coastal). The continental type has two highs (in the morning and afternoon) and two lows (at night and before noon). Marine type - one maximum (at night) and one minimum (during the day).

The annual course of precipitation is different at different latitudes and even within the same zone. It depends on the amount of heat, thermal regime, air circulation, distance from the coast, the nature of the relief. (see appendix 1)

The most abundant precipitation is in equatorial latitudes, where their annual amount (GKO) exceeds 1000-2000 mm. On the equatorial islands of the Pacific Ocean the rainfall is 4000-5000 mm, and on the leeward slopes of tropical islands up to 10000 mm. Heavy rainfall is caused by powerful ascending currents of very humid air. To the north and south of the equatorial latitudes, precipitation decreases, reaching a minimum by 25-35º, where the average annual value does not exceed 500 mm and decreases in the inland regions to 100 mm or less. In temperate latitudes, the amount of precipitation increases slightly (800 mm). At high latitudes, GKO is insignificant.

The maximum annual precipitation was recorded in Cherrapunji (India) - 26461 mm. The minimum recorded annual precipitation is in Aswan (Egypt), Iquique (Chile), where in some years there is no precipitation at all. (see appendix 2)

The annual course of precipitation, i.e. the change in their number by months, in different places of the Earth is not the same. Several basic types of annual precipitation can be outlined and expressed in the form of bar graphs.

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

· Monsoon type - maximum precipitation in summer, minimum in winter. It is characteristic of subequatorial latitudes, as well as the eastern coasts of continents in subtropical and temperate latitudes. At the same time, the total amount of precipitation gradually decreases from the subequatorial to the temperate zone.

· Mediterranean type - maximum precipitation in winter, minimum in summer. It is observed in subtropical latitudes on the western coasts and inland. Annual precipitation gradually decreases towards the center of the continents.

· Continental type of precipitation in temperate latitudes - in the warm period, precipitation is two to three times more than in the cold one. As the continentality of the climate in the central regions of the continents increases, the total amount of precipitation decreases, and the difference between summer and winter precipitation increases.

· Marine type of temperate latitudes - precipitation is distributed evenly throughout the year with a small maximum in autumn-winter. Their number is greater than that observed for this type. (see appendix 3)

Conclusion


Atmospheric precipitation is one of the main factors in the formation of surface and ground waters. Atmospheric waters are the least studied chemically, which is associated with the difficulty of taking sufficient samples for chemical analysis and insufficient attention to atmospheric precipitation as a factor in the formation of the chemical composition of surface and underground.

The chemical composition of atmospheric precipitation and dry fallout is an integral characteristic of the content of pollutants in the cloudy and subcloud layers of the atmosphere. The processes of wet deposition of substances can lead to a change in the chemical composition of soils, water of rivers and reservoirs, and this, in turn, affects the vital activity of their inhabitants. Chemical substances in atmospheric precipitation, depending on the composition, have a stimulating or depressing effect on the development of plants. Therefore, knowledge of the quantitative chemical composition of atmospheric precipitation is necessary to assess the state and forecast the consequences of environmental pollution.

Bibliography


1.Precipitation [Electronic resource] - Access mode: # "center"> Application


Annex 1


Rice. 1. Distribution of annual precipitation (mm)


Appendix 2


Table 1. Distribution of precipitation by continents as a percentage (%) of the total amount

EuropeAsiaAfricaAustraliaSouth AmericaNorth America Below 500 mm476754665216500-1000 mm49181822308 Above 1000 mm41528121876

Appendix 3


Rice. 2 Types of annual precipitation:

Equatorial, 2 - monsoon, 3 - Mediterranean, 4 - continental temperate latitudes, 5 - maritime temperate latitudes


Appendix 4


Sediment types by origin: - convective, II - frontal, III - orographic; TV - warm air, HV - cold air.


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Water molecules are constantly evaporating from the surface of lakes, seas, rivers and oceans - they enter the atmosphere, where they are converted into water vapor, and then into various types of precipitation... There is always water vapor in the air, which is usually impossible to see, but the humidity of the air depends on its amount.

Air humidity is different in all regions of the world, in heat it rises when evaporation into the atmosphere from the surface of water bodies increases. Low humidity is usually observed over desert areas, as there is little water vapor, so the air in deserts is very dry.

Water vapor overcomes many challenges before falling to the ground in the form of rain, snow or frost.

The surface of the earth is heated by the sun's rays, and the resulting heat is transferred to the air. Since heated air masses are much lighter than cold ones, they rise. Tiny water droplets that formed in the air continue to travel further with it in type of precipitation.

Types of precipitation, fog and clouds.

To imagine how the further transformation of water vapor in the atmosphere takes place, a fairly simple experiment can be carried out. It is necessary to take a mirror and bring it closer to the spout of a boiling kettle. After a few seconds, the cool surface of the mirror will fog up, then large water droplets will form on it. The released steam turned into water, which means that a phenomenon called condensation has occurred.

A similar phenomenon occurs with water vapor at a distance of 2-3 km from the ground. Since the air at this distance is colder than near the surface of the earth, vapor condensation occurs in it and water droplets are formed, which can be observed from the ground in the form of clouds.

When flying in an airplane, clouds can sometimes be seen below the aircraft. And you can even find yourself among the clouds if you climb a high mountain with low clouds. At this moment, the surrounding objects and people will turn into invisible people, who are swallowed up by a thick veil of fog. Fog is the same clouds, but only located near the earth's surface.

If the drops in the clouds begin to grow and become heavier, then the snow-white clouds gradually darken and turn into clouds. When heavy droplets are no longer able to stay in the air, then rain falls from thunderclouds onto the ground in type of precipitation.

Dew and frost as types of precipitation.

In summer, near water bodies, a lot of steam is formed in the air and it becomes very saturated with water pores. With the onset of night, coolness comes and at this time less steam is required to saturate the air. Excess moisture condenses on the ground, leaves, grass and other objects, and such type of precipitation called dew. Dew can be observed in the early morning when transparent small droplets can be seen covering various objects.

With the arrival of late autumn, the temperature during the night can drop below 0 ° C, then the dew drops freeze and turn into amazing transparent crystals called frost.

In winter, ice crystals freeze and settle on window panes in the form of frosty patterns of extraordinary beauty. Sometimes frost simply covers the surface of the earth, like a thin layer of snow. Fancy patterns are best seen on rough surfaces such as:

  • tree branches;
  • loose surface of the earth;
  • wooden benches.

Snow and hail as types of precipitation.

Hail are irregularly shaped pieces of ice that fall to the ground with rain in summer. There is also "dry" hail, it falls without rain. If you carefully cut the hailstone, you can see on the cut that it consists of alternating opaque and transparent layers.

When air currents bring water vapor to a height of about 5 km, then water droplets begin to settle on the dust particles, and they instantly freeze. The formed ice crystals begin to increase in size, and, having reached a large weight, I begin to fall. But a new stream of warm air emanates from the earth and it returns them back to the cold cloud. The gravels begin to grow again and try to fall, this process is repeated several times, as soon as they have gained enough heavy weight, they fall to the ground.

The size of such types of precipitation(grains) is usually 1 to 5 mm in diameter. Although there were cases when the size of the hailstones exceeded a hen's egg, and the weight reached about 400-800 g.

The hail can cause great damage to agriculture, it damages vegetable gardens and crops, and also leads to the death of small animals. Large hailstones can damage cars and even pierce the skin of aircraft.

To reduce the likelihood of hail falling on the ground, scientists are constantly developing new substances that, using special rockets, are thrown into thunderclouds and thus disperse them.

With the arrival of winter, a snow-white blanket envelops the earth, consisting of the smallest ice crystals called snow. Due to low temperatures, water droplets freeze and ice crystals form in the clouds, then new water molecules are attached to them, and as a result, a separate snowflake is born. All snowflakes have six corners, but the patterns woven on them by frost are different from each other. If the wind blows on the snowflakes, they stick together and form snowflakes. Walking through the snow in frosty weather, we often hear a crunch under our feet, it is ice crystals breaking in snowflakes.

Such types of precipitation How snow brings a lot of problems, snow makes it difficult to move on the roads, power lines are torn under its weight, and melting snows leads to floods. But due to the fact that the plants are covered with a snow blanket, they are able to withstand even severe frosts.

First of all, let us define the very concept of "precipitation". In the "Meteorological Dictionary, this term is interpreted as follows:" Precipitation is 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. "

According to the above definition, atmospheric precipitation can be divided into two groups: precipitation emitted directly from the air - dew, hoarfrost, rime, 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, tree leaves, roofs, etc.). Dew forms at night or in the evening in clear, calm weather.

Frost appears on surfaces cooled below 0 ° C. It is a thin layer of crystalline ice, the particles of which resemble snowflakes in shape.

Rime- This is the deposition of ice on thin and long objects (tree branches, wires), which forms at any time of the day, usually in cloudy, foggy weather at negative temperatures (below -15 ° C). Rime can be crystalline and granular. On vertical objects, frost is deposited mainly from the windward side.

Among the sediments that stand out on the earth's surface, of particular importance is ice... It is a layer of dense transparent or cloudy ice that grows on any objects (including trunks and branches of trees, bushes) and on the surface of the earth. Formed at an air temperature of 0 to -3 ° C due to freezing drops of supercooled rain, drizzle or fog. The frozen ice crust can be several centimeters thick and cause branching to break off.

Precipitation falling out of clouds is subdivided into drizzling, overlying and showers.

Drizzle (drizzle) consist of very small water droplets with a diameter of less than 0.5 mm. They are of low intensity. These precipitations usually fall from stratus and stratocumulus clouds. The droplets are falling so slowly that they appear suspended in the air.

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

Heavy rainfall it is distinguished by great intensity. These are coarse droplets and irregular precipitation, both liquid and solid (snow, groats, hail, sleet). The downpour can last from several minutes to several hours. The area covered by a rainstorm is usually small.

Hail, which is always observed during a thunderstorm, usually together with heavy rain, forms in cumulonimbus (thunderstorm) clouds of vertical development. It usually falls in a narrow strip in spring and summer, and most often between 12 and 17 hours. The duration of the hail is calculated in minutes. Within 5-10 minutes, the ground can be covered with a layer of hail 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 not hard 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, ie 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. This is what 10 mm of rainfall is for a typical garden plot.

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Precipitation is commonly understood to mean water that falls from the atmosphere to the earth's surface. They are measured in millimeters. For measurements, special devices are used - precipitation gauges or weather radars, which make it possible to measure different types of precipitation over a large area.

On average, the planet receives about a thousand millimeters of precipitation per year. All of them are not evenly distributed over the Earth. The exact level depends on the weather, relief, climatic zone, proximity to water bodies and other indicators.

What are the precipitation

From the atmosphere, water enters the earth's surface in two states: liquid and solid. Because of this feature, all types of precipitation are divided into:

  1. Liquid. These include rain, dew.
  2. Solid ones are snow, hail, frost.

There is a qualification of types of precipitation in terms of shape. So, rain is emitted with drops of 0.5 mm or more. Anything less than 0.5 mm refers to drizzle. Snow is ice crystals with six corners, but round solid precipitation is croup. It is a rounded nucleus of different diameters, which are easily squeezed in the hand. Most often, such precipitation occurs at temperatures close to zero.

Hail and ice pellets are of great interest to scientists. These two types of sediment are difficult to crush with your fingers. The croup has an icy surface; when it falls, it hits the ground and bounces off. Hail is a large ice that can reach a diameter of eight or more centimeters. Usually this type of precipitation forms in cumulonimbus clouds.

Other species

The smallest type of precipitation is dew. These are tiny droplets of water that form during condensation on the soil surface. When they come together, dew can be seen on various objects. Favorable conditions for its formation are clear nights when terrestrial objects are cooled. And the higher the thermal conductivity of an object, the more dew is formed on it. If the ambient temperature drops below freezing, a thin layer of ice crystals or frost appears.

In the weather forecast, precipitation is most often understood as rain and snow. However, not only these types are included in the concept of precipitation. It also includes liquid plaque, which forms in the form of water droplets or in the form of a continuous film of water in cloudy, windy weather. This type of precipitation is observed on the vertical surface of cold objects. At sub-zero temperatures, the plaque becomes hard, thin ice is most often observed.

The loose white sediment that forms on wires, ships and more is called frost. This phenomenon is observed in foggy frosty weather with light winds. Frost can build up quickly, breaking wires and light ship rigging.

Freezing rain is another unusual species. It occurs at negative temperatures, most often from -10 to -15 degrees. This type has some peculiarity: the drops look like balls, outside covered with ice. When dropped, their shell breaks, and the water inside is sprayed. Under the influence of negative temperatures, it freezes, forming ice.

The classification of precipitation is carried out according to other criteria. They are divided by the nature of the loss, by origin and not only.

The nature of the loss

According to this qualification, all precipitation is divided into drizzling, heavy rainfall, overburden. The latter are intense, uniform rains that can last for a long time - a day or longer. This phenomenon covers quite large areas.

Drizzling precipitation falls on small areas and is represented by small drops of water. Heavy rain refers to heavy rainfall. It goes on intensively, does not last long, and captures a small area.

Origin

By origin, frontal, orographic and convective sediments are distinguished.

Orographic falls on the slopes of the mountains. They go most abundantly if warm air of relative humidity comes from the sea.

The convective type is characteristic of the hot zone, where heating and evaporation occurs with high intensity. The same species is found in the temperate zone.

Frontal precipitation is formed when air masses with different temperatures meet. This species is concentrated in cold, temperate climates.

Quantity

Meteorologists have been observing precipitation for a long time, its amount, indicating their intensity on climatic maps. So, if you look at the annual maps, you can trace the unevenness of precipitation throughout the world. It rains most intensively in the Amazon River region, but there is little rainfall in the Sahara Desert.

The unevenness is explained by the fact that precipitation brings humid air masses that form over the oceans. This is most clearly seen in an area with a monsoon climate. Most of the moisture comes in the summer with monsoons. It rains continuously over land, such as on the Pacific coast in Europe.

Winds play an important role. Blowing from the continent, they carry dry air to northern Africa, home to the world's largest desert. And in the countries of Europe, the winds bring rains from the Atlantic.

The precipitation in the form of heavy rains is influenced by the sea current. The warm one contributes to their appearance, and the cold one, on the contrary, prevents them.

The relief of the area plays an important role. The Himalayan mountains do not allow wet winds from the ocean to the north, which is why up to 20 thousand millimeters of precipitation falls on their slopes, and on the other hand, they practically do not happen.

Scientists have found that there is a relationship between atmospheric pressure and rainfall. On the territory of the equator in the low-pressure belt, the air is constantly heated, it forms clouds and heavy rains. A large amount of precipitation occurs in other areas of the Earth. However, where the air temperature is low, precipitation is not often in the form of freezing rain and snow.

Fixed data

Scientists are constantly recording rainfall across the globe. Most of all recorded precipitation in the Hawaiian Islands, located in the Pacific Ocean, in India. Over 11,000 millimeters fell in these territories during the year. The minimum was registered in the Libyan Desert and in the Atakami - less than 45 millimeters per year, sometimes there is no precipitation in these territories for several years.