Fog: When the air contains a lot of water, if the temperature drops suddenly, the saturation of water vapor in the air drops, forming tiny water droplets in the bottom air.
Rain: When the volume of water droplets in the cloud is further expanded and the buoyancy of air is less than the gravity of water droplets, water droplets fall from the air to form rain.
Frost: Due to the large temperature difference between day and night in winter, the water evaporated from the ground during the day is contained in the air in the form of water vapor, and the temperature concentration decreases at night, which reduces the air saturation. Water vapor is separated from the air in the form of water, and forms frost on the surface of objects when it meets cold air.
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