On which layer of the atmosphere do rain clouds appear?

Rain clouds appear in the troposphere of the atmosphere.

I. Meaning of the atmosphere

The atmosphere, also known as the atmosphere, is a layer of mixed gas that surrounds the earth due to gravity. It is the outermost gas layer of the earth, surrounding the ocean and land.

There is no exact upper limit for the atmosphere. There are still thin gases and elementary particles at the height of 2000~ 16000 km above the surface. There is also a small amount of gas in the ground, soil and some rocks, which can also be regarded as a part of the atmosphere. The main components of the earth's atmosphere are nitrogen, oxygen, argon, carbon dioxide and trace gases with a proportion less than 0.04%. These mixed gases are called air.

Second, the composition of the atmosphere?

The main component of the atmosphere is nitrogen, accounting for 78.1%; Oxygen accounts for 20.9%; Argon accounts for 0.93%; There are also a small amount of carbon dioxide, rare gases (helium, neon, argon, krypton, xenon, radon) and water vapor. The air density of the atmosphere decreases with the increase of altitude. The higher the air, the thinner the air. The thickness of the atmosphere is about 1000 km, but there is no obvious boundary.

Third, the characteristics of atmospheric stratification?

The whole atmosphere shows different characteristics with different heights, which is divided into troposphere, stratosphere, ozone layer, mesosphere, thermosphere and escape layer, and then interstellar space.

Detailed introduction of troposphere

I. Definition

The troposphere is located at the bottom of the atmosphere, extending from the earth's surface to the top of the troposphere and the starting point of the stratosphere. The average thickness is about 12km, and its thickness varies from 8km above the poles of the earth to 17km above the equator. It is the densest layer in the atmosphere, where about 75% of the air quality and more than 90% of the water vapor quality are concentrated.

The lower troposphere is connected with the ground, and the height of the upper troposphere varies with geographical latitude and season. Its height varies with latitude, with the average height at low latitude 17 ~ 18km, mid latitude 10 ~ 12km and high latitude 8 ~ 9km, which is higher in summer than in winter.

Second, the characteristics

1, the temperature decreases with the increase of height: because the troposphere can not directly absorb the short-wave radiation of the sun, it can absorb the long-wave radiation reflected from the ground and heat the atmosphere from the underlying surface. So the air near the ground is heated more, and the air far from the ground is heated less. With every increase of 1 km, the temperature drops by about 6.5 degrees.

2. Air convection: Because the surface of lithosphere and hydrosphere is heated by the sun, and the lower air is heated by thermal radiation, vertical convection occurs between cold and hot air. Moreover, because the ground is divided into land and ocean, the temperature in different regions is different due to the difference of day and night and latitude, which forms the horizontal movement of air.

3. The horizontal distribution of temperature, humidity and other factors is uneven: the atmosphere is in contact with the surface, and toxic substances produced by human activities enter the air layer. Therefore, in addition to the vertical and horizontal movement of airflow, the chemical process in this layer is very active, the air mass becomes cold or hot, and water vapor forms a series of weather phenomena such as rain, snow, hail, frost, dew, clouds and fog.