Know little about clouds

Cloud is a visible polymer floating in the air, which is condensed by small water droplets or small ice crystals liquefied by water vapor in the atmosphere when it is cold. Clouds are the tangible result of the huge water cycle on the earth.

The sun shines on the surface of the earth, and water evaporates to form water vapor. Once the water vapor is supersaturated, water molecules will gather around the dust (condensation nucleus) in the air, and the generated water droplets or ice crystals will scatter sunlight in all directions, thus creating the appearance of clouds. Moreover, clouds can form various shapes, and they are divided into many kinds because of their different heights and shapes in the sky.

Clouds absorb heat from the ground and reflect it back, which helps to keep the earth warm. However, clouds also reflect sunlight directly back into space, which has a cooling effect.

The water surface of rivers, lakes and seas, as well as the moisture of soil, animals and plants, evaporates into the air and becomes water vapor. After water vapor enters the atmosphere, it turns into clouds and causes rainfall.

Extended data:

Judging the weather by clouds: 1 "There are clouds hanging in the sky and rain is dripping on the ground", and the hanging clouds refer to cirrus clouds hooked. Behind this cloud, there are often fronts (especially warm fronts), low pressure or low pressure troughs moving, which indicates that rain is coming. 2. "Battery cloud, it's raining". Battery cloud refers to fort-shaped altocumulus or fort-shaped stratocumulus, which appears in front of the trough with low pressure, indicating that the air is unstable, and thunderstorms usually come every 8- 10 hours.

3. "Clouds are horizontal and oblique, and it rains" means that the moving directions of the upper and lower clouds are inconsistent, that is to say, the height and wind direction of the clouds are inconsistent, which often occurs near the front or low pressure, so it indicates rain, and sometimes the wind direction of the clouds is opposite to the ground, so there is a saying that "if you go against the wind, the sky will change". 4. "* * * crossing the river, it's raining cats and dogs", * * * refers to the broken rain clouds in nimbostratus. The appearance of this cloud indicates that there is a lot of water vapor in nimbostratus, and a rainstorm is coming.

Sometimes broken rain clouds are blown to cloudless places by strong winds, and it is also a precursor to rain to see clouds floating across the "Galaxy" at night. 5. "Cotton cloud, rain is coming". Cotton clouds refer to flocculent cumulus clouds. The appearance of such clouds indicates that the middle atmosphere is very unstable. If there is enough water vapor in the air and there is upward movement, cumulonimbus clouds will form and thunderstorms will come.

6. "Gray cloth hangs in the sky, and the rain will continue", and the gray cloth cloud refers to nimbostratus, which is mostly formed by thickening and transforming high-level clouds. The range is very large and thick, and the water vapor in the cloud is sufficient, which often produces continuous precipitation. Baidu encyclopedia-cloud.

2. Knowledge about the cloud

Cloud is a visible polymer floating in the air, which is condensed by small water droplets or small ice crystals liquefied by water vapor in the atmosphere when it is cold. Clouds are the tangible result of the huge water cycle on the earth.

The sun shines on the surface of the earth, and water evaporates to form water vapor. Once the water vapor is supersaturated, water molecules will gather around the dust (condensation nucleus) in the air, and the generated water droplets or ice crystals will scatter sunlight in all directions, thus creating the appearance of clouds. Moreover, clouds can form various shapes, and they are divided into many kinds because of their different heights and shapes in the sky.

Clouds absorb heat from the ground and reflect it back, which helps to keep the earth warm. However, clouds also reflect sunlight directly back into space, which has a cooling effect. The water surface of rivers, lakes and seas, as well as the moisture of soil, animals and plants, evaporates into the air and becomes water vapor. After water vapor enters the atmosphere, it turns into clouds and causes rainfall.

Extended data:

See the weather from the clouds:

1, "Hook cloud is hanging in the sky, and rain is dripping on the ground". Hook cloud refers to a kind of hooked cirrus cloud. Behind this cloud, there are often fronts (especially warm fronts) and troughs of low pressure moving, which indicates that rain is coming.

2. "Battery cloud, it's raining". Battery cloud refers to fort-shaped altocumulus or fort-shaped stratocumulus, which appears in front of the trough with low pressure, indicating that the air is unstable, and thunderstorms usually come every 8- 10 hours.

3. "Clouds are horizontal and oblique, and it rains" means that the moving directions of the upper and lower clouds are inconsistent, that is to say, the height and wind direction of the clouds are inconsistent, which often occurs near the front or low pressure, so it indicates rain, and sometimes the wind direction of the clouds is opposite to the ground, so there is a saying that "if you go against the wind, the sky will change".

4. "* * * crossing the river, it's raining cats and dogs", * * * refers to the broken rain clouds in nimbostratus. The appearance of this cloud indicates that there is a lot of water vapor in nimbostratus, and a rainstorm is coming. Sometimes broken rain clouds are blown to cloudless places by strong winds, and it is also a precursor to rain to see clouds floating across the "Galaxy" at night.

5. "Cotton cloud, rain is coming". Cotton clouds refer to flocculent cumulus clouds. The appearance of such clouds indicates that the middle atmosphere is very unstable. If there is enough water vapor in the air and there is upward movement, cumulonimbus clouds will form and thunderstorms will come.

6. "Gray cloth hangs in the sky, and the rain will continue", and the gray cloth cloud refers to nimbostratus, which is mostly formed by thickening and transforming high-level clouds. The range is very large and thick, and the water vapor in the cloud is sufficient, which often produces continuous precipitation.

Sogou Encyclopedia-Cloud

3. Ask for information about the cloud

Visible polymer suspended in the atmosphere, consisting of a large number of tiny water droplets or ice crystals.

Generally, it doesn't touch the ground. If it touches the ground, it's called fog. Because the atmospheric pressure decreases with the increase of height, the air will expand and cool when it rises, and the saturated water vapor pressure will also decrease. When the water vapor in the air reaches saturation and condenses into a large number of tiny water droplets, clouds will form.

Clouds with temperatures below 0℃ are often composed of small water droplets (supercooled water droplets) and ice crystals. The appearance of clouds is varied, and its changes often reflect the structure of the atmosphere and the evolution of weather, such as the vertical temperature of the atmosphere, cloudy, sunny and cloudy weather conditions such as rainstorm, hail, tornado and typhoon. Cloud precipitation is an important water source to sustain life.

The movement of clouds can indicate the direction and speed of air flow. The cover of clouds affects the sun's radiation to the ground, thus affecting the climate and the growth of crops.

The refraction and scattering of solar light by clouds and precipitation will form colorful atmospheric light images such as halo, China, rainbow, neon and Emei Baoguang. Sometimes violent discharge occurs between clouds, leading to lightning and lightning strikes.

People often predict the weather changes in local areas according to the appearance of clouds and their photoelectric phenomena. As early as the beginning of19th century, L Howard of Britain divided clouds into different types according to their appearance.

Up to now, the name of cloud proposed by him has been adopted in meteorological observation. As for the microscopic nature of the cloud, it was determined by observing it with a microscope at the end of 19.

With the development of science and technology, people use balloons and airplanes to directly observe its microstructure, use radar to observe its macro-evolution, and use satellite images to understand the distribution and evolution of cloud systems around the world, which makes their understanding of clouds more and more comprehensive and in-depth. Classification of Clouds In meteorological observation, according to the height and shape of clouds, clouds can be divided into four categories: high clouds, middle clouds, low clouds and straight clouds, and ten genera: cirrus, cirrocumulus, cirrostratus, high cumulus, high stratus, stratus, nimbostratus, cumulus and cumulonimbus.

In cloud and precipitation physics, clouds are classified according to physical characteristics: ① according to dynamic characteristics. The vertically developing clouds formed by air convection are called convective clouds or cumulus clouds; When a large range of air gathers and rises slowly, a horizontally extending and evenly layered cloud is formed, which is called layered cloud.

② Classification according to temperature characteristics. Clouds with a temperature higher than 0℃ are called warm clouds. Clouds with temperatures below 0℃ are called Leng Yun.

③ Classification by microstructure. Clouds composed entirely of water droplets are called water clouds; A cloud composed entirely of ice crystals is called ice cloud; Clouds composed of water droplets and ice crystals are called mixed clouds.

The size of water droplets (cloud droplets) in the microstructure of clouds is different, and their radii range from a few microns to 100 microns. The distribution of cloud droplet number per unit volume with cloud droplet size is called cloud droplet spectrum.

The total number of cloud droplets per unit volume, called cloud droplet concentration, is generally101~103/cm3. In the continental air mass, the average radius of cloud droplets is small and the concentration is large; In the ocean air mass, the average radius of cloud droplets is large and the concentration is small.

There are also water droplets with a radius greater than 100 micron in the cloud, which are actually raindrops that have not fallen off from the cloud. As for the shapes of ice crystals, snow crystals and other solid particles in the cloud, they change with different growth conditions.

The concentration of ice crystals in clouds ranges from less than one per liter to several hundred per liter. The total amount of water contained in water droplets or ice crystals per unit volume of the cloud is called the water content of the cloud, which is generally10-1~100g/m3.

The water content varies greatly with the type, development stage and location of the cloud. The water content of pure ice crystal clouds can be less than 10- 1g/m3, and the water content of cumulonimbus clouds can reach100-1g/m3.

Knowledge content of cloud: Cloud cluster refers to a large-scale cloud area existing in tropical areas, and its diameter is about 4 latitudes or more, which is called cloud cluster. This is a tropical weather system.

Many tropical weather systems, such as intertropical convergence zone and tropical storms, are composed of or developed by tropical clouds. Clouds can be generally divided into: general clouds with a horizontal range of 2- 12 latitude.

A cloud consists of many cumulonimbus clouds, with cirrus complexes and popcorn clouds at the top, and the area is less than 10 square centimeter. Clouds are composed of several cumulonimbus clouds. This kind of cloud cluster is mostly found in the monsoon cloud cluster in China's * * region and the South American continent, and appears in Southeast Asia and adjacent waters from June to September. With the advance of monsoon, clouds explosively develop northward.

At 10-20 north latitude and 70- 100 east longitude, it is often covered by seasonal clouds of 1-2, making it the largest cloud cluster on the earth. The north-south width varies from several latitudes to 10 latitudes.

The east-west length can reach 20-40 radial degrees, which is closely related to the southwest monsoon activity, so it is called monsoon cloud cluster. Cloud chamber is a box-type device that can control air pressure, temperature and humidity to form clouds, which is called cloud chamber.

This is a laboratory device for cloud precipitation physics. As far as the temperature of cloud formation is concerned, cloud chamber can be divided into warm cloud chamber (cloud temperature is higher than 0℃) and Leng Yun chamber (cloud temperature is lower than 0℃). As far as cloud-making methods are concerned, they can be generally divided into expansion type, diffusion type, constant temperature type and mixed cloud chamber type. Cloud room generally consists of a main box and a set of auxiliary equipment. The main box can be cylindrical, hexahedron, cuboid, etc. Made of copper or stainless steel, or made of plastic or plexiglass.

Auxiliary equipment often includes refrigeration, cloud making, catalysis, observation and other systems. Some cloud rooms can also control airflow and are equipped with wind tunnels. The size of the cloud chamber varies greatly. The largest cloud chamber has a volume of more than 3,000 cubic meters, and the smallest cloud chamber has a volume of only tens of cubic centimeters.

Cloud chamber is often used to simulate and study the generation, growth and transformation of cloud and precipitation particles and their accompanying photoelectric phenomena under different conditions, detect the concentration of cloud nuclei and ice nuclei, and test the properties of artificial ice nuclei and hygroscopic nuclei. There are many ways to generate clouds in the cloud chamber: ① Adiabatic expansion and cooling make water vapor saturated and condense into cloud droplets; (2) The Leng Yun chamber wall descends, which leads to the decrease of humidity in the cloud chamber, reaching saturation and condensation of cloud droplets; (3) directly spraying tiny water droplets into the cloud chamber to form a cloud; (4) The cloud chamber is supersaturated to produce condensation.

Leng Yun, the mechanism of cold cloud precipitation refers to the cloud whose upper temperature is lower than 0℃ and whose lower temperature can still be higher than 0℃. The upper part of the cloud is often an ice mass, and there are supercooled water droplets and water vapor. How did Leng Yun grow up in a short time and cause rain or snowfall and hail? Its theoretical basis is the Bergeron process: temperature.

4. Scientific knowledge about the cloud, urgent

The formation of clouds is mainly caused by water vapor condensation.

As we all know, the closer to the ground, the higher the temperature in the atmosphere more than 10 kilometers from the ground, and the denser the air. The higher the altitude, the lower the temperature and the thinner the air. On the other hand, the water surface of rivers, lakes and seas, as well as the moisture of soil, animals and plants, evaporate into the air at any time and become water vapor.

After water vapor enters the atmosphere, it turns into clouds to cause rainfall, or condenses into frost dew, and then returns to the ground, permeates the soil or flows into rivers, lakes and seas. Later evaporation (sublimation) condensation (condensation) drops.

It goes on and on. After the water vapor enters the lower atmosphere from the evaporation surface, the temperature here is high and there is much water vapor. If the hot and humid air is lifted, the temperature will gradually decrease, and when it reaches a certain height, the water vapor in the air will reach saturation.

If the air continues to be lifted, there will be excess water vapor. If the temperature there is higher than 0℃, the excess water vapor will condense into small water droplets.

5. Common sense of life

When the water temperature reaches 4 degrees Celsius, the density of water is the highest.

Because the dog's Han gland is on the tongue.

When dust, ice crystals and other substances in the air roll in the cloud, they are positively charged and negatively charged through some complicated processes. After exercise, heavier substances with the same charge will reach the lower part of the cloud (generally negative charge), and lighter substances with the same charge will reach the upper part of the cloud (generally positive charge). In this way, the collection of charges of the same sex forms some charge centers. When the air between the charged centers of the opposite sex is broken down by its strong electric field, "cloud discharge" (that is, lightning) is formed.

When negatively charged clouds approach the ground downwards, the protrusions and metals on the ground will be induced to be positively charged. With the gradual enhancement of the electric field, Lei Yun will form a downward guide, and objects on the ground will form an upward flashover. When they meet, they will form a discharge to the ground. This is easy to cause lightning disasters.

Lightning is formed in the process of atmospheric movement, which is caused by intense triboelectricity and the cutting of magnetic lines by clouds.

The most common shape of lightning is dendritic, in addition to spherical, flaky and banded. The forms of lightning are cloud lightning, cloud lightning and cloud lightning. When lightning strikes between clouds, the friction between clouds forms lightning.

The formation of thunderstorm clouds

People usually call lightning clouds Lei Yun. In fact, several kinds of clouds are related to lightning, such as stratocumulus, nimbostratus, cumulonimbus, cumulonimbus, and the most important one is cumulonimbus. Lei Yun in general professional books refers to cumulonimbus clouds.

The process of cloud formation is a process in which water vapor in the air reaches saturation or supersaturation through various reasons and condenses. Water vapor saturation in the air is a necessary condition for cloud formation. The main ways are as follows:

(1) The water vapor content is unchanged, and the air is cooled;

(2) keeping the temperature constant and increasing the water vapor content;

(3) Not only the water vapor content is increased, but also the temperature is reduced.

But for the formation of clouds, the cooling process is the most important process. In the process of cooling, the cooling effect brought by ascending movement is the most common.

Cumulonimbus cloud is a kind of cloud formed in the process of strong vertical convection. Because the ground absorbs much more solar radiation heat than the air layer, the ground temperature rises more during the day, especially in summer. Therefore, due to heat conduction and heat radiation, the atmospheric temperature near the ground rises, the gas temperature inevitably expands, the density decreases, and the pressure also decreases. According to the principle of mechanics, it will rise, and the density of the air layer above it is relatively high, and it will sink. In the rising process, the hot airflow expands and depressurizes, and at the same time, it exchanges heat with the high-altitude low-temperature air, so the water vapor in the rising air mass condenses, and water droplets appear, forming clouds. In the process of strong convection, the fog droplets in the cloud further cool down and become supercooled water droplets, ice crystals or snowflakes, and gradually increase with the height. At the freezing height (-10℃), due to the latent heat released by the freezing of supercooled water, the cloud top suddenly develops upward and spreads horizontally near the tropopause, forming a cloud anvil, which is a remarkable feature of cumulonimbus clouds.

In the process of cumulonimbus cloud formation, positive and negative charges are accumulated in different parts of the cloud under the simultaneous action of atmospheric electric field, temperature difference electrification effect and debris electrification effect. When the charge accumulates to a certain extent, it will discharge between clouds or between clouds and the ground, which is what people usually call "lightning".

Lightning has brought great disasters to human society with its great destructive power, especially in recent years, lightning disasters have occurred frequently, and the harm to the national economy has become increasingly serious. It is necessary to strengthen the awareness of lightning protection, actively cooperate with meteorological departments, do a good job of prevention, and minimize the losses caused by lightning.

6. There is little knowledge about rain

The basic process of rain formation is that the water vapor in the air condenses at high altitude to form small water droplets or ice crystals, which collide with each other and become larger and larger. When the air can't hold up, it will fall down. When the low-altitude temperature is higher than 0℃, it is rain.

Clouds composed of liquid water droplets (including supercooled water droplets) are called water clouds. If the conditions for cloud droplets to grow into raindrops are met in the water cloud, and the raindrops have a certain falling speed, then it is rain or Mao Mao rain that falls.

Clouds composed of ice crystals are called ice cloud, and clouds composed of water droplets (mainly supercooled water droplets) and ice crystals are called mixed clouds. Ice crystals or snowflakes falling from ice cloud or mixed clouds fall into the gas layer above 0℃, and after melting, they also fall to the ground as raindrops, forming rainfall.

In the process of rain formation, large water droplets play an important role. When the radius of water droplets increases to 2-3 mm, it is difficult to maintain such a large water droplet by the attraction between water molecules, and it is easy to be split by the impact of airflow on the way down, through a "chain reaction."

Make big water droplets fall, and small water droplets continue to exist, forming new big water droplets. This is an important reason for the formation of rain in water clouds and mixed clouds with strong updraft.

7. Primary school students' scientific knowledge: Why do clouds in the sky have different colors?

There are clouds of different colors in the sky, some as white as floc, some as black, some as gray, some as red and purple. Here, the thickness of the cloud determines the color. The thickness of various clouds we see varies greatly, from 7-8 kilometers thick to only tens of meters thin. There are many kinds of layered clouds, isolated cumulus clouds and fluctuating clouds. Thick layered clouds, or cumulonimbus clouds, the light from the sun and the moon is difficult to transmit, and the clouds look black; Slightly thinner layered clouds and wave clouds look gray, especially in wave clouds, and the edges of the clouds are grayer; Very thin clouds, light can easily penetrate, especially thin clouds made of ice crystals. Clouds are especially bright and silky in the sun. Even if there are such layered clouds in the sky, objects on the ground will still reflect shadows under the illumination of the sun and the moon. Sometimes the clouds are so thin that you can hardly see them, but as long as you find one or several big rings near the sun and the moon, you can still tell that there are clouds. This cloud is called "cirrostratus with a thin curtain". Isolated cumulus clouds, because the clouds are thick, almost all the light is reflected to the sunny side, so it looks white;

On the backlight side and its bottom, the light is not easily transmitted and looks gray and black. At sunrise and sunset, because sunlight is oblique and passes through the thick atmosphere, molecules, water vapor and impurities in the air are scattered a lot in the short-wave part of light; However, the long-wave part of red orange is not scattered much, so when it hits the lower atmosphere, long-wave light, especially red light, accounts for an absolute majority. At this time, not only the sky in the direction of sunrise and sunset is red, but also the bottom and edge of the cloud illuminated by it become red. Because clouds are composed of water droplets, ice crystals and a mixture of the two, when the sun and the moon pass by, they will also create various beautiful light rings or rainbows.