What's the relationship between air pressure and weather?

Air pressure is one of the bases of weather forecast.

Air pressure is closely related to the weather. Generally speaking, areas with high ground pressure are often sunny, and areas with low ground pressure are often rainy.

When the air pressure in a certain area is high, the air in this area will flow out horizontally. The air above the high pressure area will drop. Because the atmospheric pressure increases with the decrease of altitude, when the air at high altitude falls, the pressure is increased, the volume is decreased, the temperature is increased, and the condensate in the air evaporates and dissipates.

Therefore, the high-pressure central area is not conducive to the formation of clouds and rain, and it is often sunny. If the air pressure in a certain area is low, the air in the surrounding area will flow into the area horizontally, causing the air in the area to rise, the rising air will expand due to the pressure drop, the temperature will drop, and the water vapor in the air will condense. Therefore, it often rains in the central area of low pressure.

Factors affecting stress level

1, elevation: the air pressure decreases with the elevation.

2. Land-sea distribution: Due to the difference of thermal properties between land and sea, the temperature and air pressure between land and sea change with seasons. In summer in the northern hemisphere, low pressure is formed on land and high pressure is formed on the ocean; Winter is the opposite.

3. Temperature: On the same horizontal plane, high temperature and low air pressure, low temperature and high air pressure.

4. Vertical movement of air: the air pressure at the updraft is often slightly lower than that at the same level; Downward flow is the opposite.

In meteorology, people usually use kilopascals (kPa) or hectopascals (hpa) as units. Other commonly used units are bar (bar, 1 bar = 100000 Pa) and centimeter mercury column (or centimeter mercury column). Air pressure varies not only with height, but also with temperature. The change of air pressure is closely related to the change of weather.