What is the air pressure when the temperature is high? High or low?

High temperature leads to low 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.

Extended data:

Influencing factors of temperature:

1, the influence of the characteristics of urban underlying surface (the contact surface between atmospheric bottom and surface)

A large number of artificial structures in the city, such as paving the ground and various building walls, have changed the thermal properties of the underlying surface. Urban surface water content is less, and more heat enters the air in the form of sensible heat, which leads to air warming. At the same time, the absorption rate of sunlight on the urban surface is higher than that on the natural surface, which can absorb more solar radiation, so that the air can get more heat and the temperature will rise.

2. Urban air pollution

Motor vehicles, industrial production and a large number of people's activities in cities produce a lot of nitrogen oxides, carbon dioxide, dust and so on, which can absorb a lot of energy from the thermal radiation in the environment, produce a well-known greenhouse effect, and cause further warming of the atmosphere.

3, the influence of artificial heat source

Factories, motor vehicles, residents' lives, etc. Burning all kinds of fuels consumes a lot of energy and countless stoves are burning and emitting heat.

4. The natural underlying surface in the city is reduced.

Buildings, squares, roads, etc. It has increased a lot in the city, and the natural factors such as green space and water body have decreased accordingly, releasing more heat and absorbing less heat, and the ability to alleviate the heat island effect has weakened.

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