Why is the air pressure higher on sunny days than on cloudy days?

The reasons why the air pressure on sunny days is higher than that on cloudy days are as follows:

First of all, there are fewer water vapor components in the air on sunny days, while there are more water vapor components in the air on cloudy days. Because the density of water vapor is less than that of air, the air density on cloudy days is less than that on sunny days. Secondly, on sunny days, cold air sinks from above, water vapor evaporates less, and there are fewer clouds in the sky. So the air pressure on sunny days is higher than that on cloudy days.

The change of atmospheric pressure is related to the weather. At different times, the atmospheric pressure in the same place is not exactly the same. You should know that the density of water vapor is less than that of air. When there is more water vapor in the air, the air density will become smaller and the atmospheric pressure will also decrease. The change of atmospheric pressure is also related to temperature.

So the air density becomes smaller when the temperature rises, so the atmospheric pressure is smaller when the temperature is high than when the temperature is low. The atmosphere usually refers to the whole layer of air around the earth. Besides nitrogen, oxygen, carbon dioxide and other gases, it also contains water vapor and dust. Air with less water vapor (i.e. low humidity) is called "dry air".

Influencing factors of air pressure:

Atmospheric pressure is related to altitude, atmospheric temperature and atmospheric density, and generally decreases exponentially with altitude. The air pressure changes every day and every year. In a year, the air pressure in winter is higher than that in summer. In a day, the air pressure has a maximum value and a minimum value, which appear at 9 ~ 10 and 15 ~ 16 respectively.

There is also a second high value and a second low value, which appear at 2 1 ~ 22 hours and 3 ~ 4 hours respectively. The daily variation of air pressure is small, generally 0. 1 ~ 0.4 kPa, and decreases with the increase of latitude. The change of air pressure is closely related to wind and weather, so it is an important meteorological factor. The commonly used units of air pressure are Pa, mmHg and millibar.

The conversion relationship between them is:100pa =1mbar ≈ 3/4 mm mercury column height. Commonly used instruments for measuring atmospheric pressure in meteorological observation include mercury barometer, empty box barometer and barometer. When the temperature is 0℃ and the pressure is 760mm, the standard atmospheric pressure is first measured by Italian scientist Torricelli.