Changes in air pressure: sunny days are _ _ _ _ than cloudy days, winter is _ _ _ _ _ than summer, and the top of the mountain is _ _ _ _.

Atmospheric pressure is not constant, it is related to altitude and weather. Generally, the air pressure is higher in sunny days than in cloudy days, and higher in winter than in summer.

At the same time, because the air pressure decreases with the increase of height, the air pressure at the top of the mountain is lower than that at the foot of the mountain;

So, the answer is: high; High; Low;