It was a sunny day, but there was a mist moving from the top of the mountain to the bottom of the mountain. Explain why.

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

This is related to the atmospheric circulation and gradient forces learned in high school geography.

Based on the principle of high temperature and low pressure, we can judge that the temperature is higher in sunny weather, so the area is low pressure in a large area. Maybe the mountains you mentioned are rich in moisture, and in the sunshine Under irradiation, it heats up and evaporates, forming a mist. The temperature inside this mist is low, and the air pressure is high when the temperature is low.

At this time, the air pressure at the top of the mountain is higher than the air pressure in other places. High pressure flows to low pressure, so the high pressure at the top of the mountain will move toward the lower pressure at the foot of the mountain. Therefore, in clear weather, there is a gap at the top of the mountain. A stream of mist moved down the mountain.

Pressure gradient force

Pressure gradient (pressure gradient), the pressure difference between unit distance is the pressure gradient, and the pressure difference represents the space vector of the uneven degree of pressure distribution. Its direction is mostly perpendicular to isobars or isobaric surfaces, from high pressure to low pressure; its size is equal to the rate of change of air pressure with distance.

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

For the above content, please refer to Baidu Encyclopedia - Pressure Gradient Force