The atmosphere is mysterious and powerful. We humans live in the atmosphere, but we don't know enough about it! In fact, people still remember the recent Hurricane Katrina, which caused great loss of people and property to the most developed countries on earth. Soon after, Typhoon Yunna, which landed on the southeast coast of China, also caused great danger ... Climate and environmental changes are major issues of common concern all over the world, and the atmosphere, as an important part of our living environment, is also one of the most important components of the earth's fluid. Now let me talk about what clouds, fog and precipitation are. Cloud is composed of many small water droplets, which is an important part of the water cycle in nature. The occurrence and development of clouds are accompanied by energy conversion. Fog is a phenomenon caused by the condensation of water vapor in the air near the surface. Because the water vapor in the air condenses into fog drops and ice crystals, the visibility is greatly reduced. In China's meteorology, it is stipulated that when the visibility is less than 10000 meters, it is recorded as fog. Precipitation refers to rain, snow, hail and other liquid or solid water falling from the clouds to the ground. What we should pay most attention to is air pollution, which refers to the phenomenon that the concentration of pollutants in the atmosphere or secondary pollutants transformed from it reaches harmful levels.