Precipitation falling from clouds. Precipitation falling from clouds The main stage. Independent work of task groups
Under certain conditions, precipitation falls out of the clouds, i.e., droplets or crystals of such large sizes that they can no longer be held in suspension in the atmosphere. The most famous and important are rain and snow. However, there are several other types of precipitation that differ from the typical forms of rain and snow.
Both rain and snow fall mainly from upslip clouds and from convection clouds. Depending on this, the nature of precipitation will be different.
From clouds of upward sliding (nimbostratus and highly stratified) associated with fronts, heavy precipitation falls. These are long-term precipitation of medium intensity. They fall immediately over large areas, on the order of hundreds of thousands of square kilometers, relatively evenly and for a sufficiently long time (hours and tens of hours). Precipitation is recorded at all stations or at most stations over a large area; in this case, the sums of precipitation at individual stations do not differ too much from one another. The largest percentage in the total amount of precipitation in temperate latitudes is precisely precipitation.
From cumulonimbus clouds associated with convection, showers fall, intense, but of short duration. Immediately after the start, they can get more intense, but just as abruptly they break off. Their comparative short duration is explained by the fact that they are associated with individual clouds or with narrow zones of clouds. In cold air masses moving over a warm earth's surface, individual heavy rains sometimes last only a few minutes over each given point. During local convection over land in the summer, when cumulonimbus clouds are especially extensive, or during the passage of fronts, showers sometimes last for hours. According to observations in the United States, the average area simultaneously covered by the same heavy rain is about 20 km 2.
With short-term precipitation, heavy rainfall can also provide a small amount of water. Their intensity fluctuates greatly. Even in the same case of rain, the amount of precipitation can vary by 50 mm at a distance of only 1-2 km. Showers are the main type of precipitation in low tropical and equatorial latitudes.
In addition to continuous and torrential precipitation, drizzling precipitation is also distinguished. These are intramass precipitation falling from stratus and stratocumulus clouds, typical of warm or locally stable air masses. The vertical power of these clouds is small; therefore, in the warm season, precipitation can fall out of them only as a result of the mutual merging of droplets. The falling liquid precipitation - drizzle - consists of very small droplets. In winter, at low temperatures, these clouds may contain crystals. Then, instead of drizzle, small snowflakes and so-called snow grains fall out of them.
As a rule, drizzling precipitation does not provide significant daily amounts. In winter, they do not noticeably increase the snow cover. Only in special conditions, such as in the mountains, can drizzle be more intense and plentiful.
Precipitation forms
Rain consists of droplets with a diameter of more than 0.5 mm, but not more than 8 mm. With larger droplets, they break into pieces when falling. In torrential rains, the size of the drops is larger than in continuous ones, especially at the beginning of the rain. At negative temperatures, rain sometimes falls in a supercooled form; in contact with the earth's surface, supercooled drops freeze, covering it with an ice crust.
Drizzle consists of droplets with a diameter of about 0.5-0.05 mm with a very low rate of precipitation; they are easily carried by the wind in a horizontal direction. Snow is made up of complex ice crystals (snowflakes). Their forms are very diverse depending on the conditions of their formation. The main form of snow crystals is a six-pointed star. Stars are obtained from hexagonal plates because the sublimation of water vapor occurs most rapidly at the corners of the plates, where the rays grow; on these rays, in turn, branches are created. The diameters of the falling snowflakes can be very different, in general, on the order of millimeters. Snowflakes, when falling, often stick together into large flakes. At temperatures close to zero and above zero, sleet or snow with rain falls. It is characterized by large flakes.
From the stratified-nimbus and cumulonimbus clouds at low temperatures, more grains fall out, snow and ice. It has the appearance of rounded (sometimes cone-shaped) nucleoli with a diameter of 1 mm or more. Most often, croup is observed at temperatures not very far from zero, especially in autumn and spring. Snow groats have a snow-like structure: grains are easily compressed by fingers. Nucleoli of ice pellets have an icy surface; it is difficult to crush them; when they fall to the ground, they jump.
In winter, instead of drizzle, snow grains fall out of stratus clouds - small grains less than 1 mm in diameter, resembling semolina.
At low winter temperatures, ice needles sometimes fall out of the clouds of the lower or middle tier - crystals in the form of hexagonal prisms and plates without branching. During significant frosts, such crystals can occur in the air near the earth's surface; they are especially well seen when they sparkle with their faces, reflecting the sun's rays. Clouds of the upper tier are also built from similar ice needles.
Ice rain has a special character in the form of transparent ice balls from 1 to 3 mm in diameter. These are raindrops frozen in the air. Their loss clearly indicates the presence of a temperature inversion. Somewhere above the earth's surface there is a layer of air with a positive temperature, in which the crystals falling from above melted and turned into droplets, and below it there is a layer with a negative temperature, where the droplets froze.
In summer, in fairly hot weather, sometimes hail falls in the form of more or less large pieces of irregularly shaped ice (hailstones), from a pea to 5-8 cm in diameter, sometimes more. The weight of hailstones in some cases exceeds 300 g. Often they show an inhomogeneous structure, namely, they consist of successive transparent and cloudy layers of ice. Hail falls from cumulonimbus clouds during thunderstorms and usually along with heavy rain.
The type and size of hailstones indicate that during their "life" hailstones are repeatedly carried up and down by strong convection currents, increasing their size by colliding with supercooled drops. In descending currents, they descend into layers with positive temperatures, where they melt from above; then they rise up again and freeze from the surface, etc.
For the formation of hailstones, a large water content of clouds is necessary, which is why hail falls only in the warm season at high temperatures near the earth's surface. The most frequent hail fall in temperate latitudes, and the most intense - in the tropics. Hail is not observed in polar latitudes. It happened that the hail remained lying on the ground for a long time in a layer of tens of centimeters. It often harms crops and even destroys them (hail damage); in some cases, animals and even people can suffer from it.
Precipitation formation
Precipitation occurs when at least some of the elements that make up the cloud (droplets or crystals) become larger for some reason. When the cloud elements become so heavy that air resistance and upward movement can no longer hold them in suspension, they fall out of the cloud as precipitation.
Enlargement of droplets to the desired size cannot occur by condensation. As a result of condensation, only very small droplets are obtained. For the formation of larger droplets, the condensation process would have to continue for an excessively long time. Larger droplets that fall out of a cloud as rain or drizzle can occur in other ways.
First, they can be the result of mutual coalescence of droplets. If the droplets are charged with opposite electric charges, this favors their merging. The difference in droplet sizes is also of great importance. With different sizes, they fall at different speeds and therefore more easily collide with each other. Collisions of droplets are also facilitated by turbulence. It is in this way that drizzle sometimes falls from stratus clouds, and fine and low-intensity rain from powerful cumulus clouds, especially in the tropics, where the content of liquid water in the clouds is high.
But heavy precipitation cannot arise by merging drops. For them to fall out, it is necessary that the clouds be mixed, that is, that they contain supercooled droplets and crystals side by side. These are the Altostratus, Strato-Nimbo and Cumulonimbus clouds. If supercooled drops and crystals are in mutual neighborhood, the humidity conditions are such that we have saturation for droplets, and supersaturation for crystals. But in this case, the crystals will grow rapidly by sublimation, the amount of water vapor in the air will decrease and for the droplets it will become unsaturated. Therefore, simultaneously with the growth of crystals, the evaporation of droplets will occur, i.e., there will be a distillation of water vapor from droplets to crystals.
Enlarged crystals usually begin to fall out from the upper part of the cloud, where they are predominantly located. Along the way, they continue to grow larger by sublimation, and in addition, they collide with supercooled droplets, freeze them to themselves and increase in size even more. Droplets frozen in contact with crystals and fragments of crystals greatly increase the number of particles on which crystallization occurs. Thus, large crystals appear in the lower part of the cloud or cloud layer. If the temperature in this lower part of the cloud is above zero, the crystals melt, turning into drops, which fall out of the cloud as rain. The resulting droplets with different falling speeds can coagulate (merge) with each other and with other cloud droplets. In other cases, the crystals melt already under the base of the cloud and rain also falls. Finally, if the temperature below the clouds is negative to the very surface of the earth, precipitation falls in the form of snow or grains. More difficult conditions occur if the precipitation falls in the form of hail or freezing rain, essentially the same phenomenon.
Precipitation can also fall from purely icy clouds, also due to sublimation coarsening of crystals. But usually these clouds are high (in the upper tier) and the precipitation from them evaporates before reaching the earth's surface. "Brooms" and "tails" of some types of cirrus clouds, in essence, are precisely the bands of falling precipitation.
Ice and icing
Of particular practical importance is the formation of an ice coating on the earth's surface and on objects as a result of drizzle or rain and during the deposition of heavy fog. This phenomenon is called ice. Ice, thus, is not released from the air by direct sublimation on ground objects, as the types of solid hydrometeors discussed above. For its formation, the precipitation of supercooled droplets that have arisen in the atmosphere is necessary.
Ice occurs at not too low negative temperatures (from 0 to -10 - -15 °). In this case, precipitation falls in the form of supercooled droplets, but upon contact with the earth's surface or objects, they freeze, covering them with an ice layer. Distinguish ice transparent and cloudy (opaque). The latter occurs with smaller droplets (drizzle) and at lower temperatures. The crust of frozen ice can reach a thickness of several centimeters (and sometimes many centimeters) and cause breakage of branches and breakage of wires; telegraph poles can fall under the weight of ice that has settled on the wires. Streets and roads can turn into solid skating rinks. Ice is plentiful in the mountains in a maritime climate; spruces in mountain forests sometimes turn into shapeless lumps of ice.
Glaze is often observed in winter in the south of the European territory of Russia. The damage caused by ice to communications and transport makes it necessary to pay special attention to its forecast.
The main amount of precipitation in the middle latitudes is given by nimbostratus clouds. But in the initial phase of their development, precipitation does not come from the clouds, in the mature stage they give extensive precipitation (i.e., over a large area at the same time), and in the stage of destruction, precipitation stops again. http://www.sgu.ru/ie/geo/meteo/R3.htm According to the physical conditions of precipitation formation, it is customary to divide it into three major genetic types: 1. Overlying, frontal2. Storm, intramass 3. Drizzling Precipitation is divided into liquid, solid and mixed depending on the type. They fall from nimbostratus, high soloist and cumulonimbus clouds. The longest continuous precipitation occurs during the passage of occlusion fronts and a warm front. Heavy precipitation usually lasts for a day or more and covers vast territories, on the order of hundreds of thousands of square kilometers. Practically at all meteorological stations located on the flat territory, approximately the same number is noted. Heavy precipitation falls in the form of rain and snow and is observed mainly in temperate and high latitudes at any time of the year. Heavy precipitation occurs mainly due to the development of intramass convection in unstable stratified air masses. Showers also form in cloud systems of cold and sometimes warm fronts. Heavy rainfall is characterized by high intensity and relatively short duration. Even showers falling from frontal cumulonimbus clouds last no more than a few hours. An exception to the above regarding the duration of showers are those falling from the cumulonimbus clouds of the Intertropical Convergence Zone, as well as during monsoons. Showers of this type continue for days and weeks, sometimes weakening, and then intensifying again. For intra-mass rainfall in temperate latitudes, even over flat areas, a very large spatial heterogeneity is characteristic. The spatial heterogeneity of heavy rainfall is manifested both in the very fact of their fallout and in the intensity and quantity. This is due to the horizontal scales of the convective cells that form the cumulonimbus cloud, as well as the structure of the cumulonimbus clouds. The maximum dimensions of convective cells, sometimes referred to as "supercells", rarely exceed 100 km. Within these limits of linear dimensions, the spatial heterogeneity of intramass rainfall is formed. Showers in temperate latitudes fall in the warm season, and in tropical latitudes all the time. Heavy precipitation falls in the form of rain, snow, hail, snow pellets. Rainfall is characterized by a rapid increase in their intensity at the beginning, large fluctuations and a sharp cessation. The intensity of heavy rainfall is maximum, in the tropics and subtropics it can reach 25-30 mm/min. Drizzling precipitation falls in the form of very fine droplets, snow grains and fine snow. They belong to intramass precipitation, sometimes precede the passage of a warm front, falling out of altostratus clouds. Drizzling precipitation falls from stratus or stratocumulus clouds. The drops, snowflakes or ice crystals that fall out of them are very small and the speed of their fall is so small that they seem to be suspended in the air. Drizzling precipitation is formed in stably stratified air masses when they are cooled to the dew point due to radiative cooling, when air masses mix over areas of the earth's surface that have different temperatures, during advection of warm air onto a cold underlying surface. In this case, fog is formed, i.e. stratus clouds, the lower boundary of which coincides with the surface, and drizzle falls from them. http://meteoweb.ru/phen040.php
Clouds are a great predictor of upcoming weather changes if there is no TV or radio nearby. It's not even worth talking about getting a forecast by cell phone - this is a deception of cell operators.
Upper clouds
Clouds of the upper tier include three subspecies of clouds. The common name of the group is pinnate.
Spindrift clouds. Such clouds never carry precipitation. But if they are present in the sky, it must be remembered that in the period from 12 hours to two days a significant change in weather and rain is possible.
Cirrocumulus. When such clouds appear, remember that a thunderstorm with heavy rain is expected in a maximum of eight hours.
Cirro-layered. If such a sign appears, then during the next three days one can expect a strong change in the weather in the direction of cooling, which is preceded by rain.
Middle clouds
Cumulus and stratus clouds of the middle tier are located at a height of 2 to 6 kilometers from the earth's surface. The probability of precipitation from them is extremely small, but at the same time, when they appear, certain conclusions can be drawn.
Altocumulus clouds. O they predict worsening weather, wind and prolonged rains with thunderstorms.
Altostratus clouds. In summer, it threatens us with a little “mushroom” rain, but in winter it will definitely bring snowfall with it.
Lower clouds
These are heavy, "lead" clouds. They are clumsy and heavy, so they do not rise above 2 kilometers from the ground.
Stratocumulus. Often such clouds bring us drizzle and fog, and in winter small grains of snow.
stratus clouds. In summer, a slight drizzle and bad weather are sometimes possible, and in winter you should not expect any precipitation at all.
Nimbostratus.
Their height is from 100 meters to 1 kilometer. Its appearance is preceded by a strong gusty wind, followed by powerful downpours and a sharp cooling of the air masses.
Cumulus clouds. These are true friends of good weather. If you saw them in the sky, tomorrow it will be sunny and nice.
Cumulonimbus clouds. They will surely bring a thunderstorm with possible hail and a sharp storm wind, there is a possibility of the formation of air vortices.
The probability of predicting by clouds, although not 100 percent, rarely fails.
Precipitation falling from the clouds
atmospheric phenomena
As already mentioned, atmospheric phenomena are precipitation (rain, snow, drizzle, hail), dew, hoarfrost, ice, fog, haze, haze, dust storm, thunderstorm, tornado, etc.
Precipitation falling from the clouds
Rain is precipitation that falls in the form of drops. Separate drops of rain, falling into the water, always leave a trace in the form of a divergent circle, and on a dry deck - a trace in the form of a wet spot.
obligatory rain - precipitation falling from nimbostratus clouds. It is characterized by a gradual beginning and end, continuous fallout or with short breaks, but without sharp fluctuations in intensity, while clouds in most cases cover the entire sky with a continuous uniform cover. Sometimes weak and short continuous rain can also fall from altostratus, stratocumulus and other clouds.
torrential rain - rain, characterized by the suddenness of the beginning and end of the fall, a sharp change in intensity. The name "shower rain" refers to the nature of the rain, not the amount of precipitation, which may be negligible. View of the sky during heavy rain; clouds are predominantly cumulonimbus, sometimes blue-lead in color, there are temporary clearings. Heavy rain is often accompanied by thunderstorms.
drizzle - precipitation in the form of very fine droplets. The droplets are so small that their fall is almost imperceptible to the eye; they are suspended in the air and participate even in its weak movement. Drizzle should not be confused with light rain, the drops of which, although very small, can still be observed falling: drops of drizzle slowly settle and their fall is imperceptible. With drizzle, circles on the water are not observed. Drizzle usually falls from stratus clouds or fog.
Snow - precipitation in the form of individual snow crystals or flakes, sometimes reaching large sizes
Covering snow Precipitation falling from nimbostratus clouds continuously or with short breaks.
Clouds cover most of the sky. solid uniform cover. Extensive snow can also fall from altostratus, stratocumulus, stratus, etc.
shower snow- snow, characterized by the suddenness of the beginning and end of precipitation, sharp fluctuations in intensity and the short duration of its most severe precipitation. The appearance of the sky during heavy snow: gray or dark gray cumulonimbus clouds, alternating with short-term clearings.
In the polar seas, frequent, very short, but heavy snowfalls are often observed, which are called snow loads.
Wet snow - precipitation falling in the form of melting snow or snow with rain.
Snow groats - precipitation falling in the form of opaque snow grains of white or dull white color of spherical shape with a diameter of 2 to 5 mm. Grains sometimes have the shape of a cone with a base in the form of a segment. They are small, fragile and easily crushed by fingers. Snow groats fall mainly at a temperature of about 0 ° C, often before or simultaneously with snow. In spring and autumn, snow groats often fall from cumulonimbus clouds in short showers during squalls in cold air masses.
Snow grains - precipitation in the form of sticks or grains, similar to snow pellets, but much smaller than it, dull white in color. Grain diameter does not exceed 1 mm. Snow grains usually fall in small quantities and mostly from stratus clouds.
Ice pellet - precipitation that falls in the form of small transparent ice grains, in the center of which there is a small white opaque core. The diameter of the grains does not exceed 3mm . The grains are hard and require little force to crush them. At air temperatures above 0 ° C, their surface is wet. Ice pellets usually fall from cumulonimbus clouds, often along with rain, and are observed mainly in spring and autumn.
hail- Precipitation falling in the form of pieces of ice of various shapes. Hailstone cores are usually opaque, sometimes surrounded by a transparent layer or several transparent and opaque layers. The diameter of the hailstones is about 5 mm, in rare cases it reaches several centimeters. Large hailstones reach a weight of several grams, and in exceptional cases - several tens of grams. Hail falls mainly in the warm season from cumulonimbus clouds and is usually accompanied by heavy rain. Abundant large hail is almost always associated with thunderstorms and strong winds.
freezing rain- Precipitation, which is small, hard, completely transparent ice balls with a diameter of 1 to 3 mm, formed from raindrops when they freeze in the lower atmosphere. They differ from ice pellets in the absence of an opaque white core.
Clouds heralding a change in the weather
Cirrostratus fibratus (Cs fib)
Cirrostratus fibratus (Cs fib) - a white veil with a weak wavy structure. The main feature of the clouds is their arrangement in the form of parallel, seemingly converging ridges. Cloud cover usually covers the entire sky. The height of the base in the middle latitudes is about 6-8 km, the thickness of the layer is from 100 meters to several kilometers. Often there is a bright halo around the sun and moon. The blue sky shines through them, and bright stars at night. Sometimes Cs are so thin and uniform that they can only be detected by the presence of a halo. Precipitation from Cs does not reach the ground, only at very low temperatures gives light snow or ice needles. They are formed as a result of adiabatic cooling of air during its upward movement in the upper troposphere in the zones of atmospheric fronts. The appearance of cloudiness Cs fib may portend a change in the weather, in the middle latitudes - rains.
Cumulus powerful - Cumulus congestus (Cu cong)
Powerful cumulus - Cumulus congestus (Cu cong) clouds strongly developed vertically. Some of them are partially torn, shaggy, in the form of towers tilted to the side. The thickness of the clouds is 1.5 - 2 times the base of the cloud. The top of the cloud is dazzling white, swirling, the base is darkened. In the central part, cumulus clouds completely cover the sun, while the edges are translucent, and crowns often form. Precipitation usually does not fall. They are formed mainly as a result of powerful ascending air currents caused by uneven heating of the underlying surface. The development of Cu cong in the summer leads to the development of cumulonimbus clouds and torrential rainfall.
Altocumulus Altocumulus (Ac)
Altocumulus Altocumulus (Ac) is a typical warm season cloud cover. It is located, as a rule, above the slopes facing the sun. Sometimes they reach the stage of powerful cumulus clouds.
Cirrus uncinus (Ci un)
Cirrus claw-shaped - Cirrus uncinus (Ci un). These are relatively small parallel strands of clouds with a comma-shaped bend at the end. They usually consist of ice crystals that form from supercooled water droplets. They differ in greater length and in that they do not fill the entire sky. Most often, clouds are observed in the presence of an ascending air flow during the onset of a warm front. Ci un are harbingers of changes in the weather. The height of the base in temperate latitudes is 7-10 km, in the tropics they reach 17-18 km. The clouds are transparent, the sun, the moon and bright stars shine through them, and sometimes the blue sky. During the day they do not reduce illumination.
Precipitation from these clouds does not fall. The formation of cirrus clouds occurs due to air cooling during the upward movement in the middle troposphere in the zone of atmospheric fronts. In the cooling air, water vapor sublimes and ice crystals form. Small ice crystals fall very slowly and can be transported to higher levels by ascending air movements.
In the evening, after sunset, Ci un remain illuminated for a long time, taking on a silvery, then golden or reddish color. In the morning, before sunrise, they are the first to be colored by the sun.
Cumulus flat Cumulus humulus (Cu hum)
Cumulus flat Cumulus humulus (Cu hum) - scattered across the sky, fairly dense clouds with clear horizontal bases, little developed vertically. They are observed mainly in the warm season. They usually appear in the morning, reach their maximum development around noon, and spread out in the evening, turning into stratocumulus evening clouds. Occasionally observed in temperate latitudes in winter. The presence of Cu hum indicates good weather and the clouds are called "good weather clouds"
High - cumulus flaky - Altocumulus floccus (Ac fl)
High - cumulus flaky - Altocumulus floccus (Ac fl) - are white flakes of clouds, broken at the edges, relatively quickly changing their outlines. They are formed at a height of 2-6 km due to the convective movement of air in a layer above 2 km. Precipitation can fall in the form of individual drops or snowflakes. Unlike cirrocumulus clouds, they can have shaded parts, which, as a rule, consist of water droplets.
Altocumulus clouds usually form as a result of the rise of warm air masses, as well as the onset of a cold front, which displaces warm air upwards. Therefore, the presence of altocumulus clouds on a warm and humid summer morning often portends the imminent appearance of thunderclouds or a change in the weather.
According to the international classification, there are 10 main types of clouds of different tiers.
> UPPER CLOUDS(h>6km) 
Spindrift clouds(Cirrus, Ci) - these are separate clouds of a fibrous structure and a whitish hue. Sometimes they have a very regular structure in the form of parallel threads or stripes, sometimes on the contrary, their fibers are tangled and scattered across the sky in separate spots. Cirrus clouds are transparent because they are made up of tiny ice crystals.
Often the appearance of such clouds portends a change in the weather. From satellites, cirrus clouds are sometimes difficult to distinguish.
cirrocumulus clouds(Cirrocumulus, Cc) - a layer of clouds, thin and translucent, like cirrus, but consisting of individual flakes or small balls, and sometimes, as it were, of parallel waves.
These clouds usually form, figuratively speaking, a "cumulus" sky. Often they appear together with cirrus clouds. They are visible before storms.
Cirrostratus clouds(Cirrostratus, Cs) - a thin, translucent whitish or milky cover, through which the disk of the Sun or Moon is clearly visible. This cover can be homogeneous, like a layer of fog, or fibrous. On cirrostratus clouds, a characteristic optical phenomenon is observed - a halo (bright circles around the Moon or the Sun, a false Sun, etc.). Like cirrus, cirrostratus clouds often indicate the approach of inclement weather.
> MIDDLE CLOUDS(h=2-6 km)
They differ from similar cloud forms of the lower layer by their high height, lower density, and higher probability of the presence of an ice phase. 
Altocumulus clouds(Altocumulus, Ac) - a layer of white or gray clouds, consisting of ridges or separate "blocks", between which the sky is usually translucent. The ridges and "clumps" that form the "feathery" sky are relatively thin and arranged in regular rows or in a checkerboard pattern, less often in disorder. Cirrus skies are usually a sign of pretty bad weather.
Altostratus clouds(Altostratus, As) - a thin, less often dense veil of a grayish or bluish hue, in some places heterogeneous or even fibrous in the form of white or gray patches throughout the sky. The sun or the moon shines through it in the form of bright spots, sometimes quite weak. These clouds are a sure sign of light rain.
> LOWER CLOUDS(h
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Slides captions:
geography teacher Khabarova N.V. PRECIPITATION
rain snow hail hoarfrost dew frost ice falling from clouds falling from the air
Why doesn't rain fall from every cloud? If the cloud consists of the smallest droplets of water, then they are so light that they cannot fall on the earth's surface. The water droplets in the cloud are constantly in motion. They collide, stick together and gradually become larger and heavier. When the droplets become so heavy that they cannot stay in the air, it starts to rain. Raindrops should be at least 0.5-5mm in diameter
why does it snow? For snow to form, the temperature in the cloud must be 0 degrees.
why does hail fall? Hailstones form in cumulonimbus clouds. Droplets of water in a cloud under the action of moving air either rise up or fall down. At the same time, they fall into the upper part of the cloud, where t is below 0. The droplet turns into an ice floe. The piece of ice sinks to the bottom of the cloud and is covered with water. Then it rises again, a layer of ice freezes on it. In the end, the hailstone becomes so heavy. that falls on the earth's surface. The sizes of the hailstones are very different.
precipitation. frost falling from the air frost A thin layer of ice crystals deposited from water vapor on a chilled surface of soil, grass, objects. It usually forms on quiet, clear nights in autumn or spring. Deposition of ice in the form of crystals on tree branches, wires that occur during fog, usually in calm, frosty weather.
precipitation falling from the air dew ice Deposition of a dense layer of ice on tree branches, wires, poles when supercooled drops of rain or fog freeze. Formed at t from 0 to -3 near the earth's surface. NOT TO BE CONFUSED WITH ICE!!! (Slippery road) Due to the cooling of the air, water vapor condenses on objects near the ground and turns into water droplets. This usually happens at night. A sufficiently strong cooling of the lower layers of air occurs when, after sunset, the surface of the earth is rapidly cooled by thermal radiation.
measuring the amount of precipitation The amount of precipitation is measured with a rain gauge. The rain gauge is like a bucket. It is installed on a pole and surrounded by special protection so that the wind does not carry precipitation to the side. When determining precipitation, water from the rain gauge is poured into a special measuring glass and the thickness of the water layer is determined in millimeters. How to determine how much snow has fallen?
Precipitation charts The sum of precipitation for all months of the year is the annual precipitation. The average long-term precipitation and the mode of their occurrence are reflected in the diagrams of the amount of precipitation. determine: 1. Annual amount of precipitation 2. Precipitation regime 3. In which month did more precipitation fall? 4. Which month had the least rainfall?
nature of precipitation. Showers are intense, short-lived, and cover a small area. Drizzling precipitation (small droplets, as if suspended in the air) Gives little moisture. convective precipitation. Characteristic of the hot zone. Where strong heating and evaporation. Heavy precipitation (of medium intensity) is uniform and covers large areas.
nature of precipitation Frontal precipitation is formed when two air masses with different temperatures and other properties meet; they fall out of warmer air, which forms cyclonic vortices. Orographic precipitation falls on the windward slopes of mountains, especially high ones. They are plentiful if the air comes from the warm sea.
Homework: Make a diagram in your notebook “Types of Precipitation” Paragraph 41
Subject, class
Geography, 6th grade
Brief summary of the project
The project was developed while studying the topic "Atmosphere". For two weeks, children collect information material, make a presentation, a booklet, and prepare messages. When working on a project, various types of independent work and knowledge control are used. Children work in a group on problematic issues, conduct research, practical work. At the end of the project, they defend their work in the form of a round table.
Questions guiding the project
Fundamental question
Will it snow or rain tomorrow?
Problematic issues
Why doesn't rain fall from every cloud?
What conditions affect precipitation?
How to determine the weather according to folk signs?
Study questions
List the types of precipitation that you know?
What is a cloud?
What is fog?
Where does precipitation fall the most?
What is the precipitation in our area?
Project plan
Acquaintance with the main theoretical issues.
Distribution of topics of students' design work, formation of a research plan for the problem.
Search work of students. Making a report in the form of a presentation, booklet
Preparatory stage.
Preparation of the necessary printed materials: (reminders on working with reference literature, searching for information on the Internet and saving information objects to external media)
Children answer questions, clarify information, discuss the task, make a general decision on the topic.
Make bookmarks for the necessary Internet resources
Main stage. Independent work of task groups
To acquaint students with the criteria for assessing intermediate and final work.
To organize the implementation of independent research by students.
Analyze the collected material.
Making presentations, compiling brochures.
Excursion to the weather station.
The final stage. Results
Thanks to everyone who helped with the project.
Place information about the project and its results on the wiki page.
Present the presentation of the project to the students.
Take a photo of the final session.
Reward the most outstanding students.
Final session
Evaluation of the work of participants
The correspondence of the content to the declared topic, the selection of materials, the logic and sequence of the presentation of the material are assessed.
Introductory presentation (publication) of the teacher
Materials for formative and final assessment
= At the beginning of the project
Questions for conversation