Why is Mount Everest so cold?

The radiation source of troposphere is not atmospheric radiation, but ground radiation, so the closer to the ground, the stronger the radiation.

Our atmosphere is divided into many layers, such as troposphere, stratosphere and upper atmosphere, which are distributed from low to high.

We know that the main components of the troposphere are water vapor, carbon dioxide and solid dust, which can absorb long-wave radiation. According to the principle of physics, objects with relatively low temperature emit long-wave radiation and objects with relatively high temperature emit short-wave radiation.

The sun radiates. The sun radiates. Because the temperature of the sun is high, solar radiation is short-wave radiation. Solar radiation cannot be absorbed by carbon dioxide, water vapor, solid dust and other substances in the troposphere, so it comes to the ground and is absorbed by the ground. Because the ground is relatively low, it emits long-wave radiation. At this time, the atmosphere can absorb the long-wave radiation from the ground, so the heat in the troposphere mainly comes from the ground. The closer to the ground, the higher the temperature will be.

There is an ozone layer in the stratosphere. Ozone can absorb short-wave radiation, so it can be directly radiated by the sun. So the stratosphere is closer to the ground and the temperature is lower.

The upper troposphere is cold and the lower troposphere is hot, which leads to the rise of hot air and the decline of cold air. In this case, air convection is active, so it is called troposphere, so the cloud and rain phenomenon in this layer is active, because the essence of cloud and rain phenomenon is convective movement.

The stratosphere makes air convection difficult and the atmosphere stable, so the plane flies in this layer.

After receiving ground radiation, the atmosphere will emit long-wave radiation because of its low temperature, which is called atmospheric inverse radiation.

The principle of greenhouse effect is that there is too much carbon dioxide in the atmosphere, which makes it easier to absorb long-wave radiation on the ground and then emit long-wave radiation. Therefore, farmers use fire to prevent frost, which is to increase the concentration of carbon dioxide and produce more atmospheric reverse radiation.

Water vapor in the clouds can also enhance the atmospheric inverse radiation, so it is hotter on cloudy nights than on sunny nights.

For this knowledge, you can check the section of atmospheric thermal conditions in the geography book "Atmospheric Environment" of senior one.

The following is my lecture notes as a tutor, and the relevant parts are pasted as follows:

3. Questions to understand:

3. 1. Difference of tropospheric thickness:

The thickness of troposphere is related to the intensity of atmospheric convection. Because the heat in the troposphere mainly comes from the ground, the thickness of the troposphere varies with latitude: in low latitudes, there is much heat, high temperature and strong convection, and the thickness of the troposphere can reach17 ~18 km; At high latitudes, there is little heating, weak convection and small troposphere thickness, only 8 ~ 9km；; The thickness of troposphere in mid-latitude area is about 10 ~ 12 km. In addition, in the same area, the thickness of troposphere in summer is greater than that in winter.

3.2. Weather conditions and daily temperature range:

In sunny days, the reflection of the atmosphere on solar radiation is weak, and the solar radiation reaching the ground is more and the temperature is higher; At night, the atmospheric inverse radiation is weak, the ground loses a lot of heat, the temperature is low, and the temperature range in sunny days is much different.

On cloudy days, during the day, the clouds reflect strongly on solar radiation, and the solar radiation reaching the ground is less and the temperature is lower; At night, the atmospheric inverse radiation is strong, the ground loses less heat, the temperature is high and the temperature difference between sunny days is small.

3.3. The relationship between atmospheric vertical distribution and atmospheric thermal conditions;

3.3. 1. Solar radiation stage: The ozone layer in the stratosphere plays the role of absorbing solar radiation.

3.3.2. Atmospheric radiation stage: water vapor and carbon dioxide in the troposphere absorb long-wave radiation on the ground and release long-wave radiation such as atmospheric radiation and atmospheric reverse radiation.

3.4. The significance of atmospheric greenhouse effect:

The weakening effect of the earth's atmosphere on solar radiation and the heat preservation effect of the ground not only reduce the maximum temperature during the day, but also increase the minimum temperature at night, thus narrowing the daily temperature difference and forming a temperature environment suitable for human survival.

3.5. The process of greenhouse effect

3.6. The fundamental reasons for the changes of various indicators in various layers of the atmosphere:

The main characteristics of vertical stratification

Troposphere 1. The temperature decreases with the increase of altitude (with the increase of 100m, the temperature decreases by about 0.6℃). Reason: The ground is the main direct heat source of the troposphere atmosphere, and the closer it is to the ground, the more it is heated.

2. The obvious reason of air convection: the upper part of this layer is cold and the lower part is hot, which is beneficial to air convection.

3. The weather phenomenon is complex and changeable: almost all water vapor and solid impurities are concentrated in this layer, and convective movement is easy to cause rainfall.

Stratosphere 1. The lower layer temperature does not change much with height; Above 30km, it rises rapidly with the increase of height. Reason: This layer of ozone absorbs a lot of solar ultraviolet rays.

2. The airflow is mainly advection.

3. Reasons conducive to high-altitude flight: this layer of atmosphere is hot and cold, and the atmosphere is stable; Less water vapor impurities, no clouds and rain, good visibility and smooth airflow.

The upper atmosphere is 1. The air pressure is low and the air density is very low.

There are several ionospheres at a height of 2.80 ~ 500 kilometers, which can reflect radio waves. The reason is that the ionosphere is highly ionized under the action of solar ultraviolet rays and cosmic rays.

3.7. The main factors affecting the intensity of solar radiation:

3.7. 1. midday sun altitude angle: area and distance.

3.7.2. Weather conditions:

The size and thickness of cloud cover have great influence on solar radiation. The thicker the cloud cover, the greater the cloud cover, the weaker the solar radiation, and the smaller the solar radiation intensity, so the solar radiation is stronger on sunny days than on cloudy days.

3.7.3. Terrain: air density, distance

3.8. Relationship between the atmosphere and human activities:

3.8. 1. Troposphere:

The troposphere is the main space for human activities, and it has the closest relationship with people living in the bottom of the troposphere.

Fossil fuels increase the content of carbon dioxide in the troposphere, causing the "greenhouse effect".

3.8.2. Stratosphere:

The ozone layer is the natural barrier of human beings;

Stable airflow, mainly horizontal movement, is conducive to high-altitude flight;

With the development of refrigeration industry, a large number of HCFCs are discharged, and the content of HCFCs in the atmosphere increases, destroying ozone.

3.8.3. Upper atmosphere:

Ionosphere plays an important role in wireless communication.

4. Several important data:

4. 1. Proportion of nitrogen, oxygen and carbon dioxide in dry and clean air

4.2. Three quarters of the atmospheric quality is concentrated in the troposphere.

4.3. Tropospheric height:

Low latitude:17 ~18km

Mid latitude:10 ~12km

High latitude: 8 ~ 9 kilometers

4.4. Stratospheric height: tropopause to 50 ~ 50 ~ 55km.

4.5. Height of ozone layer: 22 ~ 27km.

4.6. Ionospheric height: 80 ~ 500km.

4.7. Upper atmospheric limit: 2000 ~ 3000 km.