What are the three curved icons in the weather forecast?

In the weather forecast, the three curved icons are the extended data of dense fog

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Fog refers to the water vapor condensate composed of water droplets or ice crystals suspended in the atmosphere near the earth's surface, which is a common weather phenomenon. Fog can affect visibility and traffic. According to the international definition, the visibility in fog should be less than 1 km. When the temperature reaches the dew point temperature (or is close to the dew point), the water vapor in the air condenses to form fog. There are several different types of fog according to the causes of condensation.

when the water vapor contained in the air reaches the maximum, it reaches saturation. The higher the temperature, the more water vapor can be contained in the air. 1 cubic meter of air, when the temperature is 4 degrees Celsius, the maximum amount of water vapor can be 6.36 grams; When the temperature is 2 degrees Celsius, the maximum water vapor content in 1 cubic meter of air is 17.3 grams. If the water vapor in the air is more than the saturated water vapor at a certain temperature, the excess water vapor will condense out. When there is enough water, it will combine with the tiny dust particles in the air, and at the same time, the water molecules themselves will bond with each other and become small water droplets or ice crystals. The water vapor in the air exceeds saturation and condenses into water droplets, which is mainly caused by the temperature drop.

References:

Baidu Encyclopedia-Dense Fog