due to the gravity effect, from the surface of the earth, the earth's attraction is big, the molecules of air intensity is high, the impact to the high frequency, on the surface of the object of the atmospheric pressure is big. Far away from the surface of the earth, the earth less attractive, the molecules of air intensity is low, hit the frequency is low, on the surface of the object of the atmospheric pressure was low. So in different height of the atmospheric pressure on the earth is different, the smaller the higher the atmospheric pressure. In addition, the temperature and the humidity of the air of atmospheric pressure may also be affected.

in physics, the latitude to 45 degrees of sea level ( The first is zero) The perennial average atmospheric pressure regulation for standard atmospheric pressure (1 atm) 。 This standard atmospheric pressure to a certain value. Its value is 1 standard atmospheric pressure = 760 mm hg = 1. Project 033 atmospheres = 1. 5 of 0133 X 10 square handkerchief = 0. 10133 mpa

the generation of the atmospheric pressure is the result of the earth's gravitational pull, due to earth's gravity, the atmosphere was 'suck 'to the earth, and thus have the pressure, zui stressful atmosphere near the ground. Pressure on climate science, it is to point to the weight of per unit area is big column ( Atmospheric pressure) , that is, large gas column pressure on unit area.

pressure unit with mm and millibars four: with the height of mercury column to represent the air pressure units, with the mm ( 毫米) 。 Such as air pressure is 760 mm, it is said at the time of the atmospheric pressure and the pressure produced by 760 mm high mercury is equal. Another kind is the radio weather forecast often hear millibars ( mb) 。 It is made by big gas column pressure on unit area the size of the air pressure of the unit. 1 = 1000 dyne per square centimeter ( One bar = 1000 millibars) 。 So 1 millibars said on l square centimeters area by l000 dyne acting force. When air pressure is 760 mm is equivalent to 1013. 25 millibars, the pressure value is called a standard atmospheric pressure. Expressed in MMHG and millibars, our digital atmospheric pressure gauges can also use the hundred and thousand display for the unit.

is changing with height and air pressure. The higher the altitude, the smaller the atmospheric pressure; The cities of the elevation difference between the disparity, the pressure difference also.

the weight of the large gas column is also affected by the density change, the greater the density of air, which is the more per unit volume of air quality, produced by the atmospheric pressure is the greater.