How to tell the pressure of the weather?

Generally speaking, areas with high ground pressure are not conducive to the formation of clouds and rain, and it is often sunny. In the area with low air pressure on the ground, the surrounding air flows into the area horizontally, which makes the air in the area rise, the rising air expands due to the pressure drop, the temperature drops, and the water vapor in the air condenses. So it often rains in the central area with low air pressure.

1, air pressure reason

According to the theory of molecular dynamics, the pressure of gas is caused by the frequent collision of a large number of molecules with the container wall. The impact time of a single molecule on the container wall is very short, and the effect is discontinuous, but 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 wall area of the container is the pressure.

2. Classification of high voltage

According to the causes, it can be divided into dynamic high pressure and thermal high pressure. Such as subtropical high and continental cold high.

According to different thermal structures, it can be divided into cold high pressure and warm high pressure. For example: continental cold high pressure, tropical ocean air mass.

Extended data:

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, and the second high value and the second low value appear at 2 1 ~ 22 and 3 ~ 4 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.

References:

Baidu encyclopedia-high pressure

Baidu encyclopedia-air pressure

Baidu encyclopedia-low pressure weather