L. Tarasov

Like fogs, clouds arise from the condensation of water vapor into liquid and solid states. Condensation occurs either as a result of an increase in absolute air humidity or as a result of a decrease in air temperature. In practice, both factors are involved in cloud formation.

Cloud formation as a result of convection.

Formation of clouds above a warm atmospheric front.

Cloud formation over a cold front.

The decrease in air temperature is caused, firstly, by the rise (upward movement) of air masses and, secondly, by the advection of air masses - their movement in the horizontal direction, due to which warm air can appear above the cold earth's surface.

Let us limit ourselves to discussing the formation of clouds caused by a decrease in air temperature during upward movement. Obviously, such a process is significantly different from the formation of fog - after all, the fog practically does not rise upward, it remains directly at the earth's surface.

What makes air rise? Let us note four reasons for the upward movement of air masses. The first reason is air convection in the atmosphere. On a hot day, the sun's rays strongly warm the earth's surface, it transfers heat to the surface air masses - and their rise begins. Cumulus and cumulonimbus clouds most often have a convective origin.

The process of cloud formation begins with the fact that some air mass rises upward. As you rise, the air will expand. This expansion can be considered adiabatic, since the air rises relatively quickly, and therefore, if its volume is sufficiently large (and a really large volume of air is involved in the formation of a cloud), heat exchange between the rising air and environment It just doesn’t have time to happen during the ascent. During adiabatic expansion, air, without receiving heat from the outside, does work only due to its own internal energy, and then cools. So, the air rising will be cooled.

When the initial temperature T 0 of the rising air drops to the dew point T p, corresponding to the elasticity of the steam contained in it, the process of condensation of this steam will become possible. If there are condensation nuclei in the atmosphere (and they are almost always present), this process actually begins. The height H at which steam condensation begins determines the lower boundary of the forming cloud. This is called the condensation level. In meteorology, an approximate formula for height H is used (the so-called Ferrel formula):

H = 120(T 0 -T r),

where H is measured in meters.

The air that continues to flow from below crosses the condensation level, and the process of steam condensation occurs above this level - the cloud begins to develop in height. The vertical development of the cloud will stop when the air, having cooled, stops rising. In this case, a vaguely defined upper boundary of the cloud will form. It is called the level of free convection. It is located slightly above the level at which the temperature of the rising air becomes equal to the temperature of the surrounding air.

The second reason for the rise of air masses is due to the terrain. The wind blowing along the earth's surface may encounter mountains or other natural elevations along its path. Overcoming them, air masses are forced to rise upward. Formed in in this case clouds are called clouds of orographic origin (from Greek word oros, meaning "mountain"). It is clear that such clouds do not develop significantly in height (it is limited by the height of the elevation overcome by the air); in this case, stratus and nimbostratus clouds appear.

The third reason for the rise of air masses is the emergence of warm and cold atmospheric fronts. Cloud formation occurs especially intensely over a warm front - when a warm air mass, advancing on a cold air mass, is forced to slide up a wedge of retreating cold air. The frontal surface (the surface of the cold wedge) is very flat - the tangent of its angle of inclination to the horizontal surface is only 0.005-0.01. Therefore, the upward movement of warm air differs little from the horizontal movement; As a result, the cloudiness that appears above the cold wedge develops weakly in height, but has a significant horizontal extent. Such clouds are called ascending clouds. In the lower and middle tiers these are nimbostratus and altostratus clouds, and in the upper tier these are cirrostratus and cirrus (it is clear that the clouds of the upper tier are formed far behind the atmospheric front line). The horizontal extent of ascending slip clouds can be measured in hundreds of kilometers.

Cloud formation also occurs above a cold atmospheric front - when an advancing cold air mass moves under a mass of warm air and thereby lifts it. In this case, along with ascending clouds, clouds may also appear. Cumulus clouds.

The fourth reason for the rise of air masses is cyclones. Air masses, moving along the surface of the earth, swirl towards the center of the depression in the cyclone. Accumulating there, they create a vertical pressure difference and rush upward. The intense rise of air up to the boundary of the troposphere leads to powerful cloud formation - clouds of cyclonic origin appear. These can be nimbostratus, altostratus, or cumulonimbus clouds. All these clouds produce precipitation, creating the rainy weather characteristic of a cyclone.

Based on the book by L. V. Tarasov “Winds and thunderstorms in the Earth’s atmosphere.” - Dolgoprudny:Publishing house "Intellect", 2011.
Information about books from the Intellect publishing house is on the website

Clouds fly across the sky, high above our heads. They often attract the attention of adults and children. It is not surprising that you may have many questions about how clouds appear, what they are made of, how they float in the sky, what they are like, etc. In this article you will get answers to all these questions and satisfy your curiosity.

What are clouds made of?

Clouds are made up of many tiny water droplets or ice crystals floating in the sky at different altitudes.

How are clouds formed?

As the Sun heats the water, it turns into a gas called water vapor. This process is called evaporation. As water vapor rises to the sky, it cools. The higher you go, the cooler the air. Eventually, the steam becomes cool enough and condenses into water droplets, forming the clouds we see in the sky.

How do clouds float across the sky?

Clouds are lighter than the surrounding air. This means they can literally float across the sky. At the same time, air flows can increase their speed.

When clouds accumulate a lot of moisture and become heavy, it begins to rain, hail or snow.

Where do the clouds meet?

Diagram of the main layers of the Earth's atmosphere

All major types of clouds float in the troposphere; this is the lowest part closest to the Earth. Above the troposphere is the stratosphere, and above are the mesosphere, thermosphere and exosphere.

Why are the clouds different?

There are 10 main types of clouds:

Cumulus clouds

They look like fluffy cotton balls. Typically, cumulus clouds occur on calm, clear days and indicate good weather. However, under certain conditions they can become thunderstorm.

Stratus clouds

These are flat, gray, featureless layers that often lie close to the Earth's surface, obscuring the clouds above. Sometimes they can cause light rain. Fog is simply a layered cloud that has descended to ground level. And when you walk in foggy weather, you are actually walking through clouds.

Stratocumulus clouds

Stratus clouds can break up to form cumulus clouds. Or several cumulus clouds are able to join together to form layers. The distance between them characterizes this type as stratocumulus clouds.

Altostratus clouds

Altostratus clouds are found in the middle of the troposphere. They are usually thinner and lighter than laminated ones. If you look closely at the sky, you can see the sun's rays through such a cloud.

Altocumulus clouds

Like altostratus clouds, altocumulus clouds are found in the middle of the troposphere. However, there is a difference, altocumulus clouds are much smaller than cumulus clouds and consist of both ice crystals and water droplets.

Spindrift clouds

Cirrus clouds are the clouds of high level consisting entirely of ice crystals. These are thin clouds that look like a horse's tail.

Cirrocumulus clouds

These are cumulus clouds at the height of cirrus. Cirrocumulus clouds are composed entirely of ice crystals. They look like little fish scales in the sky.

Cirrostratus clouds

Cirrostratus clouds are high in the sky. They can produce wonderful optical phenomena such as Halos. The sun still shines brightly through these layers, even though the sky may be completely covered in them.

Nimbostratus clouds

Nimbostratus clouds produce persistent rain or snow that can be light to moderate. These high stratus clouds exist at low to mid-levels in the troposphere.

Cumulonimbus clouds

Also known as “cloud kings,” cumulonimbus clouds are responsible for very heavy rain and hail. Precipitation occurs over a short period of time.

They are also the only clouds that can generate lightning and thunder. Cumulonimbus clouds are very high and often extend over different layers sky.

How to distinguish between cumulus, altocumulus and cirrocumulus clouds in the sky?

You can distinguish between these types of clouds using your hand. Extend your hand towards the cloud and clench your fingers into a fist. If the cloud is larger than a fist, it is a cumulus cloud.

If the cloud is smaller than your fist, move it aside thumb. When the cloud is larger than a finger, it is altocumulus, and if it is smaller, it is most likely a cirrocumulus cloud.

Why are the clouds white?

Clouds are white because the droplets inside them are larger than the particles around them. This makes the cloud droplets capable of scattering and breaking up light into different colors, which are then combined into white.

Clouds appear gray when they become dense enough to block sunlight.

What is an airplane contrail?

Condensation trails form when planes pass through cool air. The release of warm, moist air from an airplane's exhaust pipe creates a trail of clouds in its path.

How to determine the weather by clouds?

It's difficult to accurately predict the weather using clouds, but there are some signs that can help! If the clouds are high, dark and cover the entire sky, the rain will continue. In case most of The sky is blue, light rain can be expected.

If cumulus clouds get higher and higher, you may experience sudden showers in the evening or even thunder and lightning. However, this often occurs on hot and humid days.

Meteo. Clouds in the form of thick white puffs... Dictionary of many expressions

Cumulus clouds- (cumulus)Cumulus, a cloud formation consisting of rounded shapes piled one on top of the other... Countries of the world. Dictionary

Altocumulus clouds, photo of U.S. National Oceanic and Atmospheric Administration Altocumulus clouds (lat. ... Wikipedia

- (lat. Stratocumulus, Sc) large gray ridges of plates or x ... Wikipedia

- (lat. Cirrocumulus, Cc) thin clouds consisting of small waves, flakes or ripples ... Wikipedia

stratocumulus clouds- Low clouds (symbol: Sc), predominantly stratus in the form of gray or white layers and ridges lying upwind, sometimes producing light precipitation in the form of rain, snow or drizzle... Dictionary of Geography

cirrocumulus clouds- Layers or banks of thin white clouds in the upper troposphere (above 6000 m) without shadows, consisting of small elements that look like flakes or ripples (symbol: Cc) ... Dictionary of Geography

Altocumulus clouds- (altocumulus)Altocumulus, clouds of the middle layers of the troposphere, representing rounded masses in the form of layers and ridges and consisting of tiny drops and ice crystals ... Countries of the world. Dictionary

Cirrocumulus clouds- (cirrocumulus), Cirrocumulus is the usual form of high clouds, consisting of small, round, curly clouds adjacent to each other. This kind of cloudiness is called a lamb's sky... Countries of the world. Dictionary

CLOUDS, a visible mass of water particles or ice crystals suspended in the lower atmosphere. Clouds form when water on the Earth's surface turns into steam through the process of EVAPORATION. As the steam rises into the atmosphere it cools and... Scientific and technical encyclopedic Dictionary

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Low level clouds (symbol: St) in the form of a light gray or uniform cloud layer with a fairly uniform base, usually do not produce precipitation, but sometimes they produce small particles of drizzle, ice crystals or tiny snow grains... Dictionary of Geography

Cirrostratus Cirrostratus clouds (lat. Cirrostratus) a type of cloud that is a thin, whitish cover, sometimes almost invisible ... Wikipedia

cirrostratus clouds- One of the main types of upper level clouds (above 6000 m), having the appearance of a whitish translucent veil, usually fibrous, can cover the entire sky and often causes a halo phenomenon, preceding the passage of a warm front (symbol: Cs) ... Dictionary of Geography

Highly stratus clouds- (altostratus)Altostratus, clouds of the middle layers of the troposphere with a flat, sometimes slightly wavy surface, consisting of droplets and ice crystals ... Countries of the world. Dictionary

Cirrostratus clouds- (cirrostratus),Cirrostratus are thin and usually tall white cloud formations formed by ch. o.made from tiny ice crystals; halo phenomena are associated with them... Countries of the world. Dictionary

CLOUDS, a visible mass of water particles or ice crystals suspended in the lower atmosphere. Clouds form when water on the Earth's surface turns into steam through the process of EVAPORATION. As the steam rises into the atmosphere it cools and... Scientific and technical encyclopedic dictionary

- (Clouds) a collection of tiny water droplets, ice crystals or snowflakes suspended in the air at a higher or lower altitude. The smallest droplets that make up clouds are released when moist air cools, which happens... ... Marine Dictionary

They resemble ragged cumulus clouds or ragged stratus clouds in appearance, but appear in daylight, i.e., in transmitted light, gloomy gray against the background of a lighter layer of nimbostratus or altostratus clouds. At night, above... ... Marine Dictionary

This term has other meanings, see Cloud (meanings). Clouds are products of condensation of water vapor suspended in the atmosphere, visible in the sky from the surface of the earth. Clouds are made up of tiny droplets of water and/or ice crystals... ... Wikipedia

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Hello friends! Clouds, white-maned horses... Oh, what am I talking about🙂Actually, I want to talk about how clouds form, where they form and what are the reasons for this, and also what types of clouds there are...

Masses of water vapor transported through the air are clouds. At any given time, about 50% of the earth's surface is covered by clouds. Clouds are also part of the process that provides fresh water to all living things on Earth.

As the steam rises, it cools and turns back into a solid (ice) or liquid (water) state, forming clouds (invisible masses). In the form that is carried away by streams and rivers, moisture returns to the Earth, and the cycle repeats.

How are clouds formed?

Clouds are made of ice and/or water. Everywhere there is water vapor that evaporates from the oceans and seas. The “absolute humidity” of air determines the amount of vapor in a given volume of air. The higher the temperature, the more water vapor can be contained in the air.

If the air contains the maximum amount of water vapor possible for a given temperature, it is considered “saturated” and its “relative humidity” is 100%. The "dew point" is the corresponding temperature. The process of water vapor changing into a solid or liquid state that occurs when air containing the vapor cools and becomes saturated is called condensation.

Air cooling.

As a result of the rise, the air can cool, for example when flowing over hills. At the same time, using part of its heat, it expands due to a drop in pressure (“adiabatic expansion”). Clouds form when excess water vapor condenses into water droplets when the temperature drops to a certain point.

The main reasons for rising air, which lead to its cooling, the formation of clouds and condensation: the first is turbulence caused by a sharp change in wind speed and direction and creating all the necessary conditions for cloud formation.

The second is an “orthographic rise” of air when passing over mountains and hills. In this case, there may be various types clouds: cloud cap, mountain fog, vortex, flag-like and lenticular clouds.

When moist air cools to its dew point before reaching the summit, mountain fog appears. Everything is perceived as something that has fallen into such a cloud and clings to the top and windward side.

When the air is fairly dry and cools after rising above the mountain top to the dew point, a cloud cap forms. It seems as if the cloud is hanging motionless over the top of the mountain, even despite the wind. This is not the same cloud, strictly speaking, it constantly forms on the windward side and evaporates on the leeward side.

Pennant-like, flag-like clouds form over mountain peaks when air is forced to flow around the peak on both sides, creating turbulent lift that is enough to cause a cloud and vortices to form in the moist air currents on the leeward side of the mountain.

The cloud that appeared behind the peak flows with the wind and eventually evaporates. Lenticular wavy clouds often form on the crests of undulating air currents that pass over rough terrain.

A vortex cloud in the shape of an elongated cylinder can form, located parallel to a mountain ridge on its leeward side in a turbulent vortex.

Convergence.

Inside huge weather systems - “cyclones” (areas of low pressure) air masses can also rise.

When, “fighting” for free space, warm moist masses “converge” (converge) with cold air masses - large ridges of clouds are formed. Lighter and warmer air is displaced upward - denser and colder. Often such a “front” brings prolonged rains and heavy precipitation.

The nature of the upward movement of air masses determines the shape of the clouds. Slowly rising air currents (5 - 10 cm/sec.) usually form stratus clouds, and warm air - cumulus clouds, which rise from the surface at least 100 times faster than stratus clouds.

Scientists have discovered that in these clouds, air currents can rise at speeds of up to 100 km/h, and how high they rise depends largely on the "instability" or "stability" of the air through which they pass.

The air in the cloud cools by 1°C for every 100 m rise. “Stable” conditions are when the ambient air temperature drops at a high speed, but the flow continues to rise.

"Unstable conditions" - this is when the surrounding air cools more slowly, and the updrafts soon reach the same temperature and the rise stops.

Classification of clouds.

Clouds, influenced by the many processes involved in their formation, come in different shapes, colors and sizes. Ancient scientists, long before they began to understand the reasons for the formation of clouds, tried to classify and describe their diversity.

Jean Baptiste Lamarck (1744 - 1829), the French founder of the theory of evolution, as well as a naturalist, was one of the first among them.

He proposed classifying clouds into five types and three tiers in 1802. Lamarck believed that clouds form as a result of a number of circumstances (although he did not know exactly which ones), and not by chance.

The English chemist Luke Howard, in the same 1802, developed a classification that included three main types of clouds, and also gave them Latin names: Stratus – stratus, Cirrus – cirrus and Cumulus – cumulus.

And today these basic terms are also used. The first "international cloud atlas" was published in 1896. At that time, clouds were still considered to be non-evolving, permanent masses. But the fact that every cloud has its own life cycle became clear by the 1930s.

Today, the World Meteorological Organization (WMO) distinguishes 10 main types of clouds according to their shape and height. Each type has a generally accepted abbreviation.

Soaring in the heights.

TO upper clouds include cirrostratus (Cs), cirrocumulus (Cc) and cirrus (Ci). They consist of ice crystals, are found at altitudes of 6 to 18 km, and are not a source of precipitation falling on the Earth.

Cirrus clouds have the shape of individual thin white hairs. Wavy plates or white patches resemble cirrocumulus clouds. And cirrostratus clouds look like a transparent veil thrown onto the sky.

Mid-level clouds – altostratus (As) and altocumulus (Ac) – consist of a mixture of ice crystals and water droplets, and are located at an altitude of 3 – 6 km. Altocumulus clouds look like white-gray torn plates, and altostratus clouds look like gray-blue solid sheets. Very little precipitation falls from mid-level clouds.

Low clouds (up to 3 km altitude) include stratocumulus (Cs), cumulus (Cu), nimbostratus (Ns), stratus (St) and cumulonimbus (Cb). Cumulus, stratocumulus and stratus are made up of droplets, while nimbostratus and cumulonimbus are made up of a mixture of ice and water.

Stratus and stratocumulus clouds are similar to the gray sheet, but the former are a homogeneous layer, while the latter are more fragmented. They may fall with drizzle or light rain. Nimbostratus clouds look like a dark gray layer; they carry snow or continuous rain.

Vertically rising cumulus clouds have clear outlines and a dense structure. They may be accompanied by showers. Cumulonimbus are dark, large, dense clouds (sometimes with a flat, anvil-topped cloud) associated with thunderstorms and heavy rain.

Now, by looking at the sky, you can understand what kind of clouds are there and what weather to expect...