Is the pressure high or low in cloudy weather?

Cloudy weather and low pressure.

Atmospheric pressure is the atmospheric pressure acting on a unit area, which is equal to the weight of a vertical air column extending upward to the upper boundary of the atmosphere per unit area. 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.

Standard atmospheric pressure. The unit used to express air pressure is the height of the mercury column. For example, a standard atmospheric pressure is equal to the weight of a 760 mm high mercury column, which is equivalent to an atmospheric pressure of 1.0336 kg on a square centimeter area.

Since the units of weight and length used by different countries are different, the units of air pressure are also not uniform, which makes it difficult to conduct a comparative analysis of global air pressure. Therefore, it is internationally agreed to use "hundred Pascals" as the unit of air pressure.

From the molecular kinetic theory, it can be known that the pressure of gas is generated by a large number of molecules frequently colliding with the container wall. The collision time of a single molecule against the container wall is extremely short, and the effect is discontinuous. However, a large number of molecules frequently collide with the container wall, and the force on the container wall is continuous and uniform. The ratio of this pressure to the area of ​​the container wall is the pressure. .

There are two commonly used measurement instruments in meteorology: liquid (such as mercury) barometers and solid (such as metal empty boxes) barometers. The air pressure record is measured by a barometer or barometer installed in a pressure chamber with little temperature change and sufficient light. There are timed air pressure records and continuous air pressure records.