Why is the pressure greater on sunny days than on cloudy days?

Because the temperature is high on a sunny day, the air is dry and the air density is high, so the air pressure is high; on the contrary, on a cloudy day the temperature is low, there is a lot of water vapor in the air, and the air density is low, so the air pressure is low. In addition, the air pressure in winter is higher than that in summer. Because the temperature in winter is lower than in summer, the air shrinks, becomes denser, and generates greater pressure, so the air pressure in winter is higher than in summer.

Knowledge about air pressure:

Air pressure is the atmospheric pressure acting on a unit area, that is, it is numerically equal to the force exerted on a vertical air column extending upward to the upper boundary of the atmosphere per unit area. of gravity. The famous Magdeburg hemisphere experiment proved its existence. The international unit of air pressure is Pascal, or Pascal for short, and its symbol is Pa.

In meteorology, people generally use kPa (kPa) or hectopascal (hpa) as the unit. Other commonly used units are: bar (bar, 1bar=100,000 Pa) and centimeters of mercury (or centimeters of mercury). Air pressure changes not only with altitude, but also with temperature. Changes in air pressure are closely related to weather changes.