It's sunny and foggy. Why is it foggy in the morning? It's sunny most of the time.

It is because on a clear night, there is no cloud or partial cloudy, the atmospheric inverse radiation is weak, and the ground insulation effect is poor. The intense radiation cooling on the ground makes the water vapor in the atmosphere near the ground condense and form fog when it is cold. At the same time, because there is no cloud and it is partly cloudy, the weakening effect of the atmosphere on solar radiation is reduced, especially the reflection effect of clouds is weakened, and more solar radiation directly reaches the ground, so the temperature is higher and the weather is sunny in most days.

Extended data:

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The conditions for fog formation are cooling, humidification and condensation to increase water vapor content.

A kind of fog is formed by radiation cooling, which mostly appears at night and early morning, when the weather is clear, the breeze is light, the water vapor near the ground is rich and stable, or there is inversion. Meteorology is called radiation fog;

The other is that warm and humid air moves horizontally, passing through the cold ground or water surface, and the water vapor in the air is gradually liquefied by cold to form fog, which is called advection fog in meteorology;

Sometimes the fog formed by two reasons is called mixed fog. It can be seen that it is late autumn and early winter that can meet these conditions, especially in the morning of late autumn and early winter.

Baidu Encyclopedia-Ten Fogs and Nine Sunnies