Why does it get hot?

Introduction to the greenhouse effect The greenhouse effect refers to the heat preservation effect caused by the lack of heat exchange between the enclosed space transmitting sunlight and the outside world, that is, the short-wave radiation of the sun can penetrate into the ground through the atmosphere, but the long and short radiation released after the ground warms is absorbed by substances such as carbon dioxide in the atmosphere, thus producing the effect of atmospheric warming. Carbon dioxide in the atmosphere is like a thick layer of glass, which makes the earth a big greenhouse. It is estimated that if there is no atmosphere, the average surface temperature will drop to -23℃, while the actual average surface temperature is 15℃, which means that the greenhouse effect will increase the surface temperature by 38℃. In addition to carbon dioxide, methane, ozone, chlorofluorocarbons, water vapor and other gases that play an important role in the greenhouse effect. With the rapid increase of population and the rapid development of industry, the carbon dioxide discharged into the atmosphere has also increased accordingly; Because of a large number of deforestation, the carbon dioxide that forests should absorb in the atmosphere has not been absorbed, and the greenhouse effect has been continuously enhanced because of the gradual increase of carbon dioxide. According to analysis, in the past two hundred years, the concentration of carbon dioxide has increased by 25%, and the average temperature of the earth has increased by 0.5℃. It is predicted that by the middle of the next century, the average temperature on the earth's surface will rise by 1.5-4.5℃, especially in the middle and high latitudes. The air contains carbon dioxide, which has remained basically unchanged for a long time in the past. This is because the carbon dioxide in the atmosphere is always in a dynamic equilibrium state of "increasing while consuming". 80% of carbon dioxide in the atmosphere comes from the breathing of people, animals and plants, and 20% comes from the burning of fuel. 75% of carbon dioxide scattered in the atmosphere is absorbed by groundwater and atmospheric precipitation such as oceans, lakes and rivers and dissolved in water. Another 5% of carbon dioxide is converted into organic matter through plant photosynthesis and stored. This is why carbon dioxide accounts for 0.03% (volume fraction) of air composition for many years. However, in recent decades, due to the rapid increase of population and the rapid development of industry, the carbon dioxide produced by breathing and burning coal, oil and natural gas has far exceeded the past level. On the other hand, due to deforestation, a large number of farmland has been built into cities and factories, destroying vegetation and reducing the conditions for converting carbon dioxide into organic matter. In addition, the surface water area is gradually shrinking, the precipitation is greatly reduced, the conditions for absorbing and dissolving carbon dioxide are reduced, the dynamic balance of carbon dioxide generation and transformation is destroyed, and the carbon dioxide content in the atmosphere is increased year by year. The increase of carbon dioxide content in the air changed the temperature of the earth. In the air, nitrogen and oxygen account for the highest proportion, and both of them can transmit visible light and infrared radiation. But carbon dioxide can't. It cannot penetrate infrared radiation. Therefore, carbon dioxide can prevent the surface heat from radiating into space and has the function of regulating the earth's temperature. Without carbon dioxide, the average annual temperature of the earth would be 20℃ lower than it is now. But if the carbon dioxide content is too high, it will make the earth seem to be in a pot, and the temperature will gradually rise, forming a "greenhouse effect." Besides carbon dioxide, there are other gases that can also cause the greenhouse effect. Among them, carbon dioxide accounts for about 75%, chlorofluoroalkanes account for about 15% ~ 20%, and there are more than 30 kinds of methane and nitric oxide.