What is the sign of fog?

The sign of fog is likely to be sunny.

As the old saying goes, there are clouds, ten fogs and nine sunny days, which means that if there is fog that day, it is likely to be sunny. Sure enough, at noon, it is really sunny and the temperature rises obviously. This situation does not bode well for the elderly, but it indicates that rain and snow may follow.

The sun is foggy in spring, foggy and rainy in summer, foggy and cool in autumn and foggy and snowy in winter. Simply put, foggy days can represent different climates throughout the year. Fog in spring is mostly the sun, fog in summer is mostly rain, fog in autumn represents a chill, fog in winter represents a cold current and snow. The fog appears on the day of the heavy snow solar term, which indicates a future weather trend, not the day of fog and snow in winter as we say.

Formation condition

The conditions of 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 calls it 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. The smog in the city is caused by another reason, and that is human activities. Morning and evening are the peak hours of heating boilers. Under the condition of low air pressure and low wind speed, a large number of pollutants, such as suspended solids and automobile exhaust, are not easy to diffuse, and it is easier to form smoke when they combine with water vapor in the lower air, and this kind of smoke often lasts for a long time.