Low pressure and foggy weather

On a sunny day, there is fog moving down the mountain at the foot of the mountain for the following reasons:

This is related to the atmospheric circulation and gas gradient force learned in senior high school geography.

According to the principle of high temperature and low air pressure, it can be judged that the temperature is high in sunny days, so the area is low in a large range. Perhaps the water in the mountain is rich, which heats up and evaporates under the sunlight, forming a fog, and the temperature in this fog is low, the temperature is low and the air pressure is high.

At this time, the air pressure at the top of the mountain is higher than other places, and the high pressure flows to the low pressure, so the high pressure at the top of the mountain will move to the foot of the mountain with lower air pressure, so in sunny weather, there will be fog moving down the mountain.

Pressure gradient force

Pressure gradient, the pressure difference between unit distances is the pressure gradient, and the pressure difference represents the spatial vector of the degree of uneven pressure distribution. Its direction is mostly perpendicular to the isobar or isobar surface, pointing from high pressure to low pressure; Its size is equal to the rate of change of air pressure with distance.

The existence of pressure gradient is the cause of horizontal pressure gradient force. Only when there is a pressure gradient on the horizontal plane can the atmosphere flow from the high pressure area to the low pressure area.

The above contents refer to Baidu Encyclopedia-Pressure Gradient Force.