What do you mean by high pressure and low pressure? Is the pressure dense? Thin air pressure?

Air pressure is the density of air, which is the density of air. The more air molecules, the higher the air pressure. Usually, the air pressure near the ground is high, and the farther away from the ground, the lower the air pressure.

Air pressure is the atmospheric pressure acting on the unit area, which is equal to the weight of the vertical air column extending upward to the upper limit of the atmosphere. The famous experiment in the Madeborg hemisphere proved its existence. The international system unit of air pressure is Pascal, abbreviated as Pa, and the symbol is PA.

Extended data:

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-air pressure