Precipitation is an example of their manifestation. Precipitation. Types of precipitation
Water that falls on the Earth's surface in the form of rain, snow, hail or condensed on objects as frost or dew is called precipitation. Precipitation can be heavy rainfall associated with warm fronts or showers associated with cold fronts.
The appearance of rain is due to the merging of small droplets of water in a cloud into larger ones, which, overcoming gravity, fall to the Earth. In the event that the cloud contains small particles of solids (dust particles), the condensation process proceeds faster, since they act as condensation nuclei. At negative temperatures, the condensation of water vapor in the cloud leads to snowfall. If snowflakes from the upper layers of the cloud fall into the lower ones with a higher temperature, which contains a large number of cold drops of water, 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 temperatures in the upper one. In this case, spherical snowballs with ascending air currents rise to the upper parts of the cloud with lower temperatures and freeze with the formation of spherical ice - hailstones. Then, under the influence of gravity, the hailstones fall to the Earth. They usually vary in size and can be as small as a pea to a chicken egg.
Types of precipitation
Such types of precipitation as dew, hoarfrost, hoarfrost, ice, fog, are formed in the surface layers of the atmosphere due to the 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. 
Precipitation is measured by the thickness of the water layer in millimeters. On our planet, on average, about 1000 mm of precipitation falls annually. A rain gauge is used to measure the amount of precipitation. For many years, observations have been made of the amount of precipitation in different regions of the planet, thanks 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, uneven precipitation is also noted. This is due to the peculiarities of the relief of a certain area and the prevailing wind direction. For example, on the western outskirts of the Scandinavian mountain range, 1000 mm falls per year, and on the eastern outskirts - more than two times less. Areas of land were identified, on which 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 observed in the southern regions of the Himalayas, in Central Africa (up to 10,000 mm per year).
Thus, the determining 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 climate features have a significant impact on many sectors of the human economy, including agriculture.
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For precipitation, there are different classifications.
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A distinction is made between heavy rainfall, which is associated with warm fronts, and heavy rainfall, which is associated with cold fronts.
Precipitation is measured in millimeters - the thickness of the layer of fallen water. On average, about 250 mm per year falls in high latitudes and deserts, and on the globe as a whole, about 1000 mm of precipitation per year.
Precipitation measurement is essential for any geographic survey. After all, precipitation is one of the most important links in the moisture cycle on the globe.
The determining characteristics for a particular climate are the average monthly, annual, seasonal and long-term precipitation, their daily and annual course, their frequency and intensity.
These indicators are extremely important for most sectors of the national (agricultural) economy.
Rain is a liquid precipitation - in the form of drops from 0.4 to 5-6 mm. Raindrops can leave a trace in the form of a wet spot on a dry object, on the surface of the water - in the form of a divergent circle.
There are different types of rain: icy, supercooled and rain with snow. Both supercooled rain and icy rain fall at negative air temperatures.
Supercooled rain is characterized by liquid precipitation, the diameter of which reaches 5 mm; after this type of rain, ice can form.
And freezing rain is represented by precipitation in a solid state - these are balls of ice, inside of which there is frozen water. Snow is called precipitation, which 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 variable phenomenon in the environment. Sometimes it starts to rain, sometimes it starts to wind, and after a few hours the sun will shine and the wind will subside.
But even in the variability of the weather there are regularities, despite the fact that a huge number of factors influence 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 force and cloud cover.
If we talk about the changeability of the weather, then most often it changes in temperate latitudes - in regions with a continental climate. And the weather is most stable in the polar and equatorial latitudes.
The change in weather is associated with the change of season, that is, the changes are periodic, and weather conditions repeat over time.
Every day we observe the diurnal change of the weather - the night follows the day, and for this reason the weather conditions change.
The concept of climate
The long-term weather regime is called the climate. The climate is determined in a particular area - thus, the weather regime must be stable for a certain geographical location.
In other words, climate can be called the average value of weather over a long period of time. Often this period is more than several decades.
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Heavy rainfall
Prolonged (from several hours to a day or more) atmospheric precipitation in the form of rain (common rain) or snow (common snow), falling over a large area with a fairly uniform intensity from nimbostratus and altostratus clouds on a warm front. Heavy rainfall keeps the soil moist.
Rain- liquid precipitation in the form of droplets with a diameter of 0.5 to 5 mm. Separate raindrops leave a trace in the form of a diverging circle on the surface of the water, and in the form of a wet spot on the surface of dry objects.
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. Supercooled rain is formed when falling snowflakes hit 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 through a thin layer of cold air above the earth's surface and become below freezing. However, the droplets themselves do not freeze, which is why this phenomenon is called supercooling (or the formation of "supercooled droplets").
freezing rain- solid precipitation falling at negative air temperature (most often 0 ... -10 °, sometimes up to -15 °) in the form of solid transparent ice balls with a diameter of 1-3 mm. Formed when raindrops freeze as they fall through a lower layer of sub-zero air. 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. With 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 (at the same time, snowfall intensifies gradually, so that visibility values of 1-2 km or less are observed no earlier than an hour after the start of snowfall). In frosty weather (air temperature below -10…-15°) light snow can fall from a cloudy sky. Separately, the phenomenon of wet snow is noted - mixed precipitation that falls at a positive air temperature in the form of flakes of melting snow.
Rain with snow- mixed precipitation falling (most often at positive air temperature) in the form of a mixture of drops and snowflakes.
Precipitation
If rain with snow falls at a negative air temperature, particles of precipitation freeze on objects and ice forms.
Drizzling precipitation
drizzle- liquid precipitation in the form of very small drops (less than 0.5 mm in diameter), as if floating in the air. A dry surface gets wet slowly and evenly. Settling on the surface of the water does not form diverging circles on it.
supercooled drizzle- liquid precipitation in the form of very small drops (less than 0.5 mm in diameter), as if floating in the air, falling out at negative air temperature (most often 0 ... -10 °, sometimes up to -15 °) - settling on objects, drops freeze and form ice.
snow grains- solid precipitation 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- accumulation of condensation products (droplets or crystals, or both), suspended in the air, directly above the earth's surface. Cloudiness of the air caused by such accumulation. Usually these two meanings of the word mist do not differ. In fog, horizontal visibility is less than 1 km. Otherwise, haze is called haze.
heavy rainfall
Shower- short-term precipitation, usually in the form of rain (sometimes - wet snow, cereals), characterized by high intensity (up to 100 mm / h). Occur in unstable air masses on a cold front or as a result of convection. Typically, heavy rain covers a relatively small area.
torrential rain- torrential rain.
shower 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) over a period of time from several minutes to half an hour (snow "charges").
Heavy rain with snow- Mixed precipitation of a shower character, falling out (most often at positive air temperature) in the form of a mixture of drops and snowflakes. If heavy rain with snow falls at a negative air temperature, particles of precipitation freeze on objects and ice forms.
snow grits- solid precipitation of a shower character, falling out at an air temperature of about zero ° and having the form of opaque white grains with a diameter of 2-5 mm; grains are fragile, easily crushed by fingers. It often falls before or at the same time as heavy snow.
ice grits- solid precipitation of a shower character, falling out at an air temperature of +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 is an opaque core. The grains are quite hard (they are crushed with fingers with some effort), and 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 the hailstones is 2-5 mm, but in some cases individual hailstones reach the size of a pigeon and even a chicken egg ( then hail causes significant damage to vegetation, car surfaces, breaks window panes, etc.). The duration of the hail is usually small - 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 tiny 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, going from the lanterns up into the sky. They are observed most often in clear or slightly cloudy skies, sometimes they fall 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 1197 cm. Cherrapunji in India arguably ranks second in terms of rainfall 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 rainfall in some cities around the world, London gets 61 cm of rain per year, Edinburgh about 68 cm and Cardiff about 76 cm. New York gets about 101 cm of rain. Ottawa in Canada gets 86 cm, Madrid about 43 cm and Paris 55 cm. So you see what a contrast Cherrapunji is.
The driest place in the world is probably Arica in Chile. Here the rainfall is 0.05 cm per year. The driest place in the US is Greenland Ranch in Death Valley. There, the average annual rainfall is less than 3.75 cm.
In some vast regions of the Earth, heavy rainfall occurs all year round. For example, almost every point along the equator receives 152 cm or more of precipitation each year. The equator is the junction of two great streams of air. Throughout the equator, air moving down from the north meets air moving up from the south.
There is a main upward movement of hot air mixed with water vapor. As the air rises to colder altitudes, a large amount of water vapor condenses and falls as rain.
Most of the rain falls on the windward side of the mountains. The other side, called the leeward side, receives much less precipitation. 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 the condensation of water vapor, which falls as 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 from convective cumulonimbus, and at the equator from cumulus clouds, and insignificant - early in the morning from stratus clouds, between them there are minima: at night and before noon.
What is precipitation? What types of precipitation do you know?
In the marine (coastal) type, there is one precipitation maximum at night (due to unstable air stratification and convection) and one minimum during the day. These types of daily precipitation patterns are observed throughout the year in the hot zone, while in the temperate zones they 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. This depends on many factors: the radiation regime, the general circulation of the atmosphere, the specific physical and geographical situation, etc. Several main types of annual precipitation can be identified and expressed in the form of bar charts (Fig. 47).
Rice. 47. Types of the annual course of precipitation on the example of the northern hemisphere
Equatorial type - heavy precipitation falls fairly evenly throughout the year, there are no dry months, two small maximums are noted - in April and October, after the days of the equinoxes, and two small minimums in July and January, after the days of the solstices.
Monsoon type - maximum precipitation in summer, minimum - in winter. It is characteristic of subequatorial latitudes, where the annual course of precipitation is very pronounced due to the dryness of winter, as well as the eastern coasts of continents in subtropical and temperate latitudes. However, the annual precipitation amplitude is somewhat smoothed here, especially in the subtropics, where frontal rains also fall in winter. The annual amount of precipitation at the same time 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 two to three times more precipitation falls here in summer than in winter, due to frontal and convective precipitation.
Marine type - precipitation is distributed evenly throughout the year with a small 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 one moves deeper into the continents.
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Atmospheric 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 air temperature. The temperature decreases from the equator to the poles; consequently, both the intensity of evaporation and the moisture capacity of the air decrease in the same direction. In cold regions, evaporation is small, and cold air is not able to dissolve much water vapor in itself; therefore, during condensation, a large amount of precipitation cannot be released from it. In warm regions, strong evaporation and a high moisture capacity of the air lead, when water vapor condenses, to abundant precipitation. Thus, a regularity must inevitably manifest itself on Earth, which consists in the fact that in warm regions there is especially a lot of precipitation, while in cold regions there is little of it. This regularity actually manifests itself, but, like other phenomena in nature, it is complicated, and in some places 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 areas on Earth, this inevitably leads to a smoothing of differences in the amount of precipitation caused by the distribution of temperatures in areas where 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 those places where descending air movements predominate (in subtropical maxima, in anticyclones in general, in the area of the trade winds, on the 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 its distance from the sea. In fact, many examples are known when very dry regions of the Earth are located on the ocean coasts and, conversely, far from the sea, inland (as, for example, on the eastern slope of the Andes in the upper reaches of the Amazon), a huge amount of precipitation falls. The point here is not so much in the distance from the sea, but in 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 without irrigating it with rain, since the flat relief does not impede the movement of air, and the heated desert has a rather drying effect on 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 single out orographic precipitation as a special type testifies to the exceptionally large role of the structure of the earth's surface in the distribution of precipitation. True, in this case, as in all others, the relief is important not only in itself, as a mechanical obstacle, but in combination with absolute height and atmospheric circulation.
The penetration of warm sea currents into high latitudes contributes to the formation of 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 the others. In each case, the precipitation of atmospheric moisture is regulated by a complex and sometimes contradictory interaction of both general and local agents. However, leaving aside the details, the main conditions that determine the distribution of precipitation in the landscape envelope still include temperature, general atmospheric circulation, and topography.
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Recently, in different parts of the world, problems associated with the amount and nature of precipitation have increasingly arisen. This year in Ukraine there was a very snowy winter, but at the same time in Australia there was an unprecedented drought. How does precipitation occur? What determines the nature of the fallout and many other issues are relevant and important today. Therefore, I chose the topic of my work "Formation and types of precipitation."
Thus, the main goal of this work is to study the formation and types of precipitation.
In the course of work, the following tasks are distinguished:
- Definition of the concept of precipitation
- Investigation of existing types of precipitation
- · Consideration of the problem and consequences of acid rain.
The main method of research in this work is the method of research and analysis of literary sources.
Atmospheric precipitation (Greek atmos - steam and Russian to precipitate - fall to the ground) - water in liquid (drizzle, rain) and solid (grain, snow, hail) form, falling out of clouds as a result of condensation of vapor rising in mainly from the oceans and seas (evaporated water from land is about 10% of precipitation). Precipitation also includes frost, hoarfrost, dew, deposited on the surface of terrestrial objects during the condensation of vapors in moisture-saturated air. Atmospheric precipitation is a link in the general moisture cycle of the Earth. With the onset of a warm front, heavy and drizzling rains are common, and with a cold front, showers. Atmospheric precipitation is measured using a precipitation gauge at meteorological stations with the thickness of the water layer (in mm) that fell during the day, month, year. The average amount of atmospheric precipitation on the Earth is about 1000 mm / year, but in deserts less than 100 and even 50 mm / year falls, and up to 12000 mm / year in the equatorial zone and on some windward slopes of mountains (Charranuja weather station at an altitude of 1300 m). Atmospheric precipitation is the main supplier of water to streams that feed the entire organic world into soils.
The main condition for the formation of precipitation is the cooling of warm air, leading to the condensation of the vapor contained in it.
When warm air rises and cools, clouds are formed, consisting of water droplets. Colliding in a cloud, the drops are connected, their mass increases. The bottom of the cloud turns blue and it rains. At negative air temperatures, water droplets in the clouds freeze and turn into snowflakes. Snowflakes stick together into flakes and fall to the ground. During a snowfall, they can melt a little, and then it snows. It happens that air currents repeatedly lower and raise frozen drops, at which time ice layers grow on them. Finally, the drops become so heavy that they fall to the ground like hail. Sometimes hailstones reach the size of a chicken egg. In summer, when the weather is clear, the earth's surface cools. It cools the surface layers of air. Water vapor begins to condense on cold objects - leaves, grass, stones. This is how dew forms. If the surface temperature was negative, then the water droplets freeze, forming frost. Dew usually falls in summer, frost in spring and autumn. At the same time, both dew and frost can form only in clear weather. If the sky is covered with clouds, then the earth's surface cools slightly and cannot cool the air.
According to the method of formation, convective, frontal and orographic precipitation are distinguished. The general condition for the formation of precipitation is the upward movement of air and its cooling. In the first case, the reason for the rise of air is its heating from a warm surface (convection). Such precipitation falls all year round in the hot zone and in summer in temperate latitudes. If warm air rises when it interacts with colder air, then frontal precipitation is formed. They are more characteristic of temperate and cold zones, where warm and cold air masses are more common. The reason for the rise of warm air may be its collision with the mountains. In this case, orographic precipitation is formed. They are characteristic of the windward slopes of mountains, and the amount of precipitation on the slopes is greater than on the adjacent parts of the plains.
The amount of precipitation is measured in millimeters. On average, about 1100 mm of precipitation falls on the earth's surface per year.
Precipitation falling from clouds: rain, drizzle, hail, snow, grains.
Distinguish:
- heavy precipitation associated mainly with warm fronts;
- showers associated with cold fronts. Precipitation from the air: dew, frost, frost, ice. Precipitation is measured by the thickness of the layer of fallen water in millimeters. On average, about 1000 mm of precipitation per year falls on the globe, and less than 250 mm per year in deserts and at high latitudes.
Precipitation measurement is carried out by rain gauges, precipitation gauges, pluviographs at meteorological stations, and for large areas - with the help of radar.
Long-term, average monthly, seasonal, annual precipitation, their distribution over the earth's surface, annual and daily course, frequency, intensity are the defining characteristics of the climate, which are essential for agriculture and many other sectors of the national economy.
The greatest amount of precipitation on the globe should be expected where atmospheric humidity is high and where there are conditions for raising and cooling the air. The amount of precipitation depends: 1) on latitude, 2) on the general circulation of the atmosphere and related processes, 3) on the relief.
The greatest amount of precipitation both on land and on the sea falls near the equator, in the zone between 10 ° N. sh. and 10°S sh. Further north and south, precipitation decreases in the trade winds, with precipitation minima more or less coinciding with subtropical pressure maxima. At sea, precipitation minima are located closer to the equator than on land. However, the figures illustrating the amount of precipitation at sea cannot be particularly trusted due to the small number of observations.
From the subtropical pressure maxima and precipitation minima, the amount of these latter increases again and reaches a second maximum at approximately 40-50° latitudes, and from here decreases towards the poles.
A large amount of precipitation under the equator is explained by the fact that here, due to thermal causes, an area of low pressure is created with ascending currents, air with a high content of water vapor (on average e = 25 mm), rising, cools and condenses moisture. The low rainfall in the trade winds is due to these last winds.
The lowest amount of precipitation observed in the area of subtropical pressure maxima is explained by the fact that these areas are characterized by downward movement of air. As the air descends, it heats up and becomes dry. Further to the north and south, we enter the area of prevailing southwestern and northwestern winds, i.e. winds moving from warmer to colder countries. Here, in addition, cyclones often occur, therefore, conditions are created that are favorable for raising the air and cooling it. All this entails an increase in precipitation.
As for the decrease in the amount of precipitation in the polar region, it must be borne in mind that they refer only to measured precipitation - rain, snow, croup, but frost deposition is not taken into account; meanwhile, it must be assumed that the formation of hoarfrost in polar countries, where, due to the low temperature, the relative humidity is very high, occurs in large quantities. Indeed, some polar travelers observed that condensation occurs here mainly from the lower layers of air in contact with the surface in the form of frost or ice needles, settling on the surface of snow and ice and significantly increasing their power.
Relief has a huge influence on the amount of moisture falling out. Mountains, forcing the air to rise, cause its cooling and condensation of vapors.
One can especially clearly trace the dependence of the amount of precipitation on height in such settlements, which are located on the slopes of mountains, and their lower quarters are at sea level, and the upper ones are located quite high. Indeed, in each locality, depending on the totality of meteorological conditions, there is a certain zone, or height, at which the maximum condensation of vapor occurs, and above this zone the air becomes drier. So, on Mont Blanc, the zone of greatest condensation lies at an altitude of 2600 m, in the Himalayas on the southern slope - an average of 2400 m, in the Pamirs and Tibet - at an altitude of 4500 m. Even in the Sahara, mountains condense moisture.
According to the time of maximum precipitation, all countries can be divided into two categories: 1) countries with prevailing summer and 2) countries with prevailing winter precipitation. The first category includes the tropical region, the more continental regions of temperate latitudes, and the northern land margins of the northern hemisphere. Winter precipitation prevails in subtropical countries, then in the oceans and seas, as well as in countries with a maritime climate in temperate latitudes. In winter, the oceans and seas are warmer than the land, the pressure decreases, favorable conditions are created for the occurrence of cyclones and increased precipitation. We can establish the following divisions on the globe based on the distribution of precipitation.
Types of precipitation. Hail - called a special kind of ice formations that sometimes fall out of the atmosphere and are classified as precipitation, otherwise hydrometeors. The type, structure and size of hailstones are extremely diverse. One of the most common forms is conical or pyramidal with sharp or slightly truncated tops and a rounded base. The upper part of such is usually softer, matte, as if snowy; medium - translucent, consisting of concentric, alternating transparent and opaque layers; the lower one, the widest one, is transparent.
No less common is a spherical shape, consisting of an inner snow core (sometimes, although less often, the central part consists of transparent ice) surrounded by one or more transparent shells. The phenomenon of hail is accompanied by a special characteristic noise from the impact of hailstones, reminiscent of the noise that comes from the spilling of nuts. Most of the hail falls during the summer and during the day. Hail at night is a very rare occurrence. It lasts several minutes, usually less than a quarter of an hour; but there are times when it lasts longer. The distribution of hail on earth depends on latitude, but mainly on local conditions. In tropical countries, hail is a very rare phenomenon, and there it falls almost only on high plateaus and mountains.
Rain - liquid precipitation in the form of droplets with a diameter of 0.5 to 5 mm. Separate raindrops leave a trace in the form of a diverging circle on the surface of the water, and in the form of a wet spot on the surface of dry objects.
Supercooled rain - liquid precipitation in the form of drops with a diameter of 0.5 to 5 mm, falling at negative air temperatures (most often 0 ... -10 °, sometimes up to -15 °) - falling on objects, the drops freeze and ice forms. Supercooled rain is formed when falling snowflakes hit 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 through a thin layer of cold air above the earth's surface and become below freezing. However, the droplets themselves do not freeze, which is why this phenomenon is called supercooling (or the formation of "supercooled droplets").
Freezing rain - solid precipitation that falls 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. Formed when raindrops freeze as they fall through a lower layer of sub-zero air. There is unfrozen water inside the balls - falling on objects, the balls break into shells, water flows out and ice forms. Snow - solid precipitation that falls (most often at negative air temperatures) in the form of snow crystals (snowflakes) or flakes. With 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 (at the same time, snowfall intensifies gradually, so that visibility values of 1-2 km or less are observed no earlier than an hour after the start of snowfall). In frosty weather (air temperature below -10…-15°) light snow can fall from a cloudy sky. Separately, the phenomenon of wet snow is noted - mixed precipitation that falls at a positive air temperature in the form of flakes of melting snow. Rain with snow - mixed precipitation that falls (most often at a positive air temperature) in the form of a mixture of drops and snowflakes. If rain with snow falls at a negative air temperature, particles of precipitation freeze on objects and ice forms.
Drizzle - liquid precipitation in the form of very small drops (less than 0.5 mm in diameter), as if floating in the air. A dry surface gets wet slowly and evenly. Settling on the surface of the water does not form diverging circles on it.
Fog is an accumulation of condensation products (droplets or crystals, or both) suspended in the air, directly above the surface of the earth. Cloudiness of the air caused by such accumulation. Usually these two meanings of the word mist do not differ. In fog, horizontal visibility is less than 1 km. Otherwise, haze is called haze.
Downpour - short-term precipitation, usually in the form of rain (sometimes - wet snow, cereals), characterized by high intensity (up to 100 mm / h). Occur in unstable air masses on a cold front or as a result of convection. Typically, heavy rain covers a relatively small area. Shower snow - snow of a shower character. 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) over a period of time from several minutes to half an hour (snow "charges") . Snow groats - solid precipitation of a shower character, falling out at an air temperature of about zero ° and having the form of opaque white grains with a diameter of 2-5 mm; grains are fragile, easily crushed by fingers. It often falls before or at the same time as heavy snow. Ice pellets - solid precipitation of a shower character, falling out at an air temperature of +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 is an opaque core. The grains are quite hard (they are crushed with fingers with some effort), and 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.
Dew (Latin ros - moisture, liquid) - atmospheric precipitation in the form of water droplets deposited on the surface of the earth and ground objects when the air cools.
Hoarfrost - loose ice crystals that grow on tree branches, wires and other objects, usually when drops of supercooled fog freeze. It is formed in winter, more often in quiet frosty weather as a result of sublimation of water vapor with a decrease in air temperature.
Hoarfrost is a thin layer of ice crystals that form on cold, clear and quiet nights on the surface of the earth, grasses and objects with a negative temperature, and lower than the air temperature. Frost crystals, like frost crystals, are formed by sublimation of water vapor.
Acid rain was first recorded in Western Europe, in particular Scandinavia, and North America in the 1950s. Now this problem exists throughout the industrial world and has acquired particular importance in connection with the increased technogenic emissions of sulfur and nitrogen oxides. precipitation acid rain
When power plants and industrial plants burn coal and oil, huge amounts of sulfur dioxide, particulate matter and nitrogen oxides are emitted from their stacks. In the United States, power plants and factories account for 90 to 95% of sulfur dioxide emissions. and 57% nitrogen oxides, with almost 60% sulfur dioxide emitted by tall pipes, which facilitates their transport over long distances.
As discharges of sulfur dioxide and nitric oxide from stationary sources are carried by the wind over long distances, they form secondary pollutants such as nitrogen dioxide, nitric acid vapors and droplets containing solutions of sulfuric acid, sulfate and nitrate salts. These chemicals reach the earth's surface in the form of acid rain or snow, but also in the form of gases, veils, dew or particulate matter. These gases can be directly absorbed by the foliage. The combination of dry and wet precipitation and the absorption of acids and acid-forming substances from near or on the earth's surface is called acid precipitation or acid rain. Another cause of acid rain is the release of nitric oxide to large numbers of cars in large cities. This type of pollution poses a threat to both urban and rural areas. After all, water droplets and most solid particles are quickly removed from the atmosphere, acid precipitation is more of a regional or continental problem than a global one.
Effects of acid rain:
- Damage to statues, buildings, metals and car trim.
- · Loss of fish, aquatic plants and microorganisms in lakes and rivers.
- Weakening or loss of trees, especially conifers that grow at high altitudes, due to the leaching of calcium, sodium and other nutrients from the soil Damage to the roots of trees and the loss of numerous fish species due to the release of aluminum ions from soils and milk precipitation, lead, mercury and cadmium
- · Weakening trees and increasing their susceptibility to diseases, insects, droughts, fungi and mosses that bloom in an acidic environment.
- · Decreased growth of crops such as tomatoes, soybeans, beans, tobacco, spinach, carrots, broccoli and cotton.
Acid precipitation is already a major problem in northern and central Europe, the northeastern United States, southeastern Canada, parts of China, Brazil and Nigeria. They are beginning to pose a growing threat in the industrial regions of Asia, Latin America and Africa and in some places in the western United States (mainly due to dry precipitation). Acid precipitation also falls into the ranks of tropical regions, where industry is practically not developed, mainly due to the release of nitrogen oxides during the combustion of biomass. Most of the acid-forming substances produced by a water country are transported by predominant surface winds to the territory of another. More than three-quarters of acid precipitation in Norway, Switzerland, Austria, Sweden, the Netherlands and Finland is brought to these countries by wind from the industrial regions of Western and Eastern Europe.
List of used literature
- 1. Akimova, T. A., Kuzmin, A. P., Khaskin, V. V., Ecology. Nature - Man - Technique: A textbook for universities. - M .: UNITI - DANA, 2001. - 343s.
- 2. Vronsky, V. A. Acid rains: an ecological aspect / / Biology at school. - 2006. - No. 3. - p. 3-6
- 3. Isaev, A. A. Ecological climatology. - 2nd ed. correct and additional .- M .: Scientific world, 2003.- 470s.
- 5. Nikolaykin, N. I., Nikolaykina N. E., Melekhova O. P. ecology. - 3rd ed. revised and additional .- M .: Bustard, 2004.- 624 p.
- 6. Novikov, Yu. V. Ecology, environment, man: Textbook.- M.: Grand: Fair - press, 2000.- 316s.
Precipitation called drops of water and ice crystals falling from clouds or settling from the air to the earth's surface. Precipitation from clouds provides more than 99% of the total amount of water coming from the atmosphere to the earth's surface; less than 1% is precipitation from the air.
Precipitation x is characterized by quantity and intensity. Precipitation measured by the thickness (expressed in mm or cm) of the layer of water they would form on the surface of the earth in the absence of seepage, runoff and evaporation. Intensity - this is the amount of precipitation falling per unit of time (per minute or per hour).
A necessary condition for the formation of precipitation is the enlargement of cloud elements to such a size that the rate of fall of these elements becomes greater than the rate of ascending flows. The consolidation process occurs mainly for the following reasons:
a) due to the recondensation of water vapor from water droplets to ice crystals or from
small drops into large ones. This is because the saturation elasticity over ice crystals is less than over water drops, and over large drops is less than over small ones.
b) due to the merging (coagulation) of water drops during their collision as a result of turbulent air movements and different falling velocities of large and small drops. These collisions lead to the absorption of small droplets by large ones.
Droplet growth due to condensation prevails until the droplet radius becomes 20–60 µm, after which coagulation becomes the main process of cloud element enlargement.
Clouds of varnish that are homogeneous in their structure, i.e. consisting only of the same
droplet sizes or only from ice crystals, do not give precipitation. Such clouds include cumulus and altocumulus, consisting of small water droplets, as well as cirrus, cirrocumulus and cirrostratus, consisting of ice crystals.
In clouds consisting of droplets of different sizes, larger drops slowly grow at the expense of smaller ones. However, as a result of this process, only small drops of rain are formed. Such a process occurs in stratus and sometimes in stratocumulus clouds, from which precipitation can fall in the form of drizzle.
c) the main types of precipitation fall from mixed clouds, in which cloud elements grow larger due to the freezing of supercooled droplets on ice crystals. The enlargement of cloud elements proceeds rapidly and is accompanied by rain or snow. These clouds include cumulonimbus, nimbostratus, and altostratus.
Precipitation from clouds can be liquid, solid or mixed.
The main forms of precipitation are:
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Wet snow– precipitation consisting of melting snow at a temperature of – 0°…+5°С.
snow grits- soft milky-white opaque rounded grains with a diameter of 2 ... 5 mm.
ice grits - transparent grains with a dense white core in the center. Grain diameter less than 5 mm. It is formed in those cases when raindrops or partially melted snowflakes freeze when falling through the lower layer of air with a negative temperature.hail– precipitation in the form of pieces of ice of various sizes. Hailstones have an irregular or spherical (close to spherical) shape, their size ranges from 5 mm to 10 cm or more. Therefore, the weight of hailstones can be very large. In the center of the hailstones there is a whitish translucent grain covered with several layers of transparent and opaque ice.
freezing rain– small transparent spherical particles with a diameter of 1…3 mm. They are formed when raindrops freeze, falling through the lower layer of air with a negative temperature (rain at a temperature of 0° ... 5°C).
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According to the nature of the drop, depending on the physical conditions of education,
duration and intensity, precipitation is divided into three types:
1. Heavy rainfall - these are long-term, medium-intensity precipitation in the form of rain drops or snow flakes, which are observed simultaneously over a large area. These precipitations fall from the system of frontal nimbostratus and altostratus clouds.
2. heavy rainfall - these are short-term, high intensity and precipitation in the form of large drops, large flakes of snow, sometimes ice pellets or hail, which are usually observed over small areas. They fall out of cumulonimbus, and sometimes powerful cumulus (in the tropics) clouds. Usually they begin suddenly, do not last long, but in some cases they can be repeatedly renewed. Heavy rainfall is often accompanied by thunderstorms and squalls.
3. Drizzling precipitation - very small drops, the smallest snowflakes or snow grains, settling from the clouds to the ground almost imperceptibly to the eye. They are observed simultaneously over a large area, their intensity is very low and is usually determined not by the amount of precipitation, but by the degree of deterioration of horizontal visibility. They fall out of stratus and stratocumulus clouds.
Precipitation released directly from the air include: dew, frost, frost, liquid or solid deposits on the windward side of vertically arranged objects.
Dew- this is liquid precipitation in the form of small droplets of water that form on summer nights and in the morning on objects located near the surface of the earth, plant leaves, etc. Dew is formed when moist air comes into contact with cooled objects, which causes water vapor to condense.
Frost- this is a white fine-crystalline deposit formed as a result of the sublimation of water vapor in those cases when the temperature of the surface air and the underlying surface is below 0 ° C;
High moisture content, slightly cloudy weather and weak wind contribute to the formation of dew and hoarfrost. This process involves a layer of air with a thickness
200 ... 300 m and more. Frost that forms on the surface of an aircraft on the ground must be carefully removed before departure, as this can lead to serious consequences due to the deterioration of the aerodynamic qualities of the aircraft.
frost It is white, loose, snow-like ice. It is formed in foggy frosty weather with a very weak wind on the branches of trees and shrubs, wires and other objects. The formation of frost is mainly associated with the freezing of the smallest supercooled droplets colliding with various objects. The snowy bang of rime rime can be the most bizarre shape. It easily crumbles when shaken off, but with an increase in temperature and a new cold snap, it can freeze and freeze.
Liquid and solid plaque It is formed on the windward part and vertically located objects cooled to a temperature below the ambient air temperature. In warm weather, a liquid coating is formed, and at surface temperatures below 0°C, white translucent ice crystals are formed. This type of precipitation can form at any time of the day with sharp warming in the cold season.
Snowstorms are a special form of precipitation transport. There are three types of blizzards:
snow drift, blowing snow, and general snowstorm.
snow drift and blowing snow are formed during the transfer of dry snow over the surface of the earth. A snow drift is formed when the wind is 4…6 m/s, the snow rises to heights up to 2 m above the ground. A blowing snow blizzard is formed when the wind is 6 m / s or more, the snow rises to a height of more than 2 m above the ground. At common blizzard (does not have its own icon) there is snowfall from the clouds, wind of 10 m/s or more, the rise of previously fallen snow from the ground and visibility less than 1000 m.
All types of precipitation complicate flight operations. The effect of precipitation on flights depends on their type, the nature of precipitation and air temperature.
1. In precipitation, visibility deteriorates and the lower boundary of the clouds decreases. In moderate rain, when flying at low speed, horizontal visibility deteriorates to 4–2 km, and at high flight speed, to 2–1 km. A significant deterioration in horizontal visibility is observed when flying in a snowfall zone. In light snow, visibility usually does not exceed 1–2 km, and in moderate and heavy snow it deteriorates to several hundred meters. In torrential precipitation, visibility deteriorates sharply to several tens of meters. The lower boundary of clouds in the precipitation zone, especially at atmospheric fronts, drops to 50–100 m and can be located below the decision height.
2. Precipitation in the form of hail causes mechanical damage to aircraft. At high speed and flight, even small hailstones can make significant dents and destroy the cockpit glazing. Hail is sometimes found at a considerable height: small hail is observed at a height of about 13 km, and large hail is observed at a height of 9.5 km. The destruction of the glazing at a high altitude can lead to depressurization, which is very dangerous.
3. When flying in a freezing rain zone, intense icing is observed
aircraft.
4. Prolonged heavy precipitation in the warm season a causes waterlogging of the soil and puts unpaved airfields out of action for one time or another, disrupts the regularity of departure and reception of aircraft.
5. Heavy rainfall degrades the aerodynamic qualities of the aircraft, which can lead to stall. In this regard, they landed in heavy rainfall with a visibility of less than 1000 m forbidden .
6. During VFR flights in the snowfall zone over a snow-covered surface, the contrast of all objects on the earth's surface is significantly reduced and, therefore, orientation deteriorates greatly.
7. When landing on a wet or snow-covered runway, the length of the run of the aircraft increases. Slip on a runway covered with snow is 2 times greater than on a concrete runway.
8. When an aircraft takes off from a runway covered with slush, hydroplaning may occur. The wheels of the aircraft throw off powerful jets of water and slush, there is a strong deceleration and an increase in the length of the takeoff run. Conditions may be created that the aircraft will not reach liftoff speed and a dangerous situation will arise.
9. Snow falling in winter requires additional work on its cleaning and compaction on runways, taxiways and parking areas where aircraft and other machines and mechanisms are serviced.
Precipitation- water in a liquid or solid state, falling out of clouds or deposited from the air on the earth's surface.
Rain
Under certain conditions, cloud drops begin to merge into larger and heavier ones. They can no longer be retained in the atmosphere and fall to the ground in the form rain.
hail
It happens that in summer the air rises quickly, picks up rain clouds and carries them to a height where the temperature is below 0 °. Raindrops freeze and fall out as hail(Fig. 1).
Rice. 1. Origin of hail
Snow
In winter, in temperate and high latitudes, precipitation falls in the form of snow. Clouds at this time do not consist of water droplets, but of the smallest crystals - needles, which, when combined together, form snowflakes.
dew and frost
Precipitation that falls on the earth's surface not only from clouds, but also directly from the air, is dew and frost.
The amount of precipitation is measured by a rain gauge or rain gauge (Fig. 2).
Rice. 2. The structure of the rain gauge: 1 - outer case; 2 - funnel; 3 - a container for collecting oxen; 4 - measuring tank
Classification and types of precipitation
Precipitation is distinguished by the nature of precipitation, by origin, by physical condition, seasons of precipitation, etc. (Fig. 3).
According to the nature of the precipitation, there are torrential, continuous and drizzling. Rainfall - intense, short, capture a small area. Overhead precipitation - medium intensity, uniform, long (can last for days, capturing large areas). Drizzling precipitation - fine-drop precipitation falling over a small area.
By origin, precipitation is distinguished:
- convective - characteristic of the hot zone, where heating and evaporation are intense, but often occur in the temperate zone;
- frontal - formed when two air masses with different temperatures meet and fall out of warmer air. Characteristic for temperate and cold zones;
- orographic - fall on the windward slopes of mountains. They are very abundant if the air comes from the warm sea and has a high absolute and relative humidity.
Rice. 3. Types of precipitation
Comparing the annual amount of precipitation in the Amazonian lowland and in the Sahara Desert on the climate map, one can be convinced of their uneven distribution (Fig. 4). What explains this?
Precipitation is brought by moist air masses that form over the ocean. This is clearly seen in the example of territories with a monsoon climate. The summer monsoon brings a lot of moisture from the ocean. And over land there are continuous rains, as on the Pacific coast of Eurasia.
Constant winds also play a large role in the distribution of precipitation. Thus, the trade winds blowing from the continent bring dry air to northern Africa, where the largest desert in the world, the Sahara, is located. Western winds bring rain from the Atlantic Ocean to Europe.
Rice. 4. Average annual distribution of precipitation on the Earth's land
As you already know, sea currents affect precipitation in the coastal parts of the continents: warm currents contribute to their appearance (Mozambique current off the eastern coast of Africa, Gulf Stream off the coast of Europe), cold ones, on the contrary, prevent precipitation (Peruvian current off the western coast of South America) .
The relief also affects the distribution of precipitation, for example, the Himalayan mountains do not allow moist winds blowing from the Indian Ocean to the north. Therefore, up to 20,000 mm of precipitation sometimes falls a year on their southern slopes. Humid air masses, rising along the slopes of the mountains (ascending air currents), cool, saturate, and precipitation falls from them. The territory north of the Himalayan mountains resembles a desert: only 200 mm of precipitation falls there per year.
There is a relationship between belts and rainfall. At the equator - in the low pressure belt - constantly heated air; as it rises, it cools and becomes saturated. Therefore, in the region of the equator, a lot of clouds form and there are heavy rains. A lot of precipitation also falls in other areas of the globe where low pressure prevails. At the same time, air temperature is of great importance: the lower it is, the less precipitation falls.
Downward air currents predominate in high pressure belts. The air, descending, heats up and loses the properties of the state of saturation. Therefore, at latitudes of 25-30 °, precipitation is rare and in small quantities. High-pressure areas near the poles also receive little precipitation.
Absolute maximum precipitation registered on about. Hawaii (Pacific Ocean) - 11,684 mm / year and Cherrapunji (India) - 11,600 mm / year. Absolute minimum - in the Atacama Desert and the Libyan Desert - less than 50 mm / year; sometimes precipitation does not fall at all for years.
The moisture content of an area is moisture factor- the ratio of annual precipitation and evaporation for the same period. The moisture coefficient is denoted by the letter K, the annual rainfall is denoted by the letter O, and the evaporation rate is denoted by I; then K = O: I.
The lower the humidity coefficient, the drier the climate. If the annual precipitation is approximately equal to evaporation, then the moisture coefficient is close to unity. In this case, moisture is considered sufficient. If the moisture index is greater than one, then the moisture excess, less than one - insufficient. If the moisture coefficient is less than 0.3, moisture is considered meager. Zones with sufficient moisture include forest-steppes and steppes, while zones with insufficient moisture include deserts.
The main factor that has a significant impact on the progress of the flora and fauna of 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 taught in the 2nd grade in the subject "World around".
What is precipitation
A strict definition of precipitation in geography is usually given 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 to various states of aggregation and precipitation on the surface of the planet.
The main classification of precipitation is division by temperature of atmospheric fronts:
- obligatory– associated with warm air currents;
- storm 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 the layer of liquid water that has fallen on a solid surface. The 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 state of aggregation of water in which it enters 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 represents.
The most common type of precipitation is rain(applies to convective precipitation). This phenomenon is formed under the influence of the radiant energy of the Sun, which heats the moisture on the surface of the Earth and evaporates it.
Getting into the upper layers of the atmosphere, which are noticeably colder, water condenses, forming a cluster of tiny droplets. As soon as the amount of condensate reaches a large mass, the water spills onto the ground in the form of heavy rain.
Types of rain are classified according to the size of the drops, which in turn is related to the currents and air temperature.
A variety of rains is formed as follows - if the air is warm, then it forms larger drops, and if it is cold, then drizzling light rain (supercooled rain) can be observed. When the temperature drops, it rains with snow.
Another process related to condensation is dew drop. 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 limiting volume of vapor is reached, condensation does not occur, but as soon as the amount exceeds the desired value, the excess precipitates into a liquid state. We can observe this in the early morning on the street, looking at the 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 on the ground, the drops are significantly cooled by air jets that have a negative temperature, and microscopic ice crystals form.
Since the process of formation of snowflakes occurs in the air and under the influence of different temperatures, this causes a large number of shapes and crystals of snowflakes.
If the temperature is very low, then blanket snow forms, if it is closer to zero, then heavy snow. Wet snow forms at temperatures slightly above freezing.
One of the dangerous atmospheric phenomena is deg. Its formation occurs mainly in summer, when heated air flows carry vaporous moisture to the upper layers of the 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 cause of 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 solid surfaces, forming frost.
Types of precipitation by seasons of the year
Often a characteristic based on the seasonality of precipitation is used.
So, there are:
- precipitation falling mainly during the warm season- rain, drizzle (subtype of rain), dew, hail;
- precipitation that occurs during the cold season- snow, groats (a subspecies of snow), hoarfrost, frost, ice.
Types of precipitation by formation height
More accurate is the classification, which takes into account at what height the condensate turned into one of the types of precipitation:
- precipitation that forms in the upper and middle layers of the atmosphere includes rain, drizzle, hail, grains and snow - falling from clouds;
- Precipitation that forms in the immediate vicinity of the earth's surface (orographic precipitation) includes mainly condensation phenomena (examples are dew, hoarfrost, frost 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 weather forecasters at weather stations using special equipment - precipitation gauges.
These are graduated buckets (on which 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 (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 graduated cylinder (cylinder divisions are made in mm).
The obtained values are recorded in the log book, forming a table of precipitation. If the precipitates were solid, then it is allowed to melt them.
To build a visual picture, points with measured precipitation are marked on the map. These points are connected into a diagram by lines - isohyets, and the space is painted over with the colors of precipitation with increasing intensity.
How precipitation affects aviation operations
There are a number of very important atmospheric factors that hinder the operation of aviation. First of all, it is connected with ensuring flight safety.
The main ones are:
- First of all, this is a deterioration in visibility for aircraft pilots. The decrease in visibility in heavy rain or a snowstorm occurs up to 1.5-2 km, which makes it difficult to visually control the course.
- During takeoff or landing, moisture condensation on windows or optical reflectors can lead to a distorted perception of information by the pilot.
- A large amount of water fine dust, if it enters the engine, can make it difficult and disrupt its operation.
- When the aerodynamic elements of the aircraft (wings, steering elements) are iced, there is a loss of flight characteristics.
- When a significant amount of precipitation falls, contact with the runway coating is 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, as well as geographic zones. Conditional separation is carried out depending on seasonality, however, it should be remembered that combinations can occur in the off-season. Precipitation is also the most important element of water circulation on the planet.