What is the relationship between atmospheric pressure and altitude?

In the natural environment, atmospheric pressure and oxygen partial pressure are affected by many factors, such as changes in temperature, humidity, wind speed and altitude, which will lead to corresponding changes in atmospheric pressure and oxygen partial pressure. Among them, the influence of altitude is the most significant, which is inversely proportional to atmospheric pressure and oxygen partial pressure. With every increase of 100 m, the atmospheric pressure will drop by 5 mm Hg (0.67 kPa), and the partial pressure of oxygen will also drop by about 1 mmHg (0.10.4 kPa). With an average elevation of more than 4,000 meters, our region is known as the roof of the world. High altitude leads to the formation of low air pressure and low oxygen partial pressure, which is also the fundamental reason why the thin and anoxic air on the Qinghai-Tibet Plateau has become the "roof of the world". Of course, the proportion of oxygen in the atmosphere has not changed, and it is still 2 1%.

The relationship between atmospheric pressure and altitude is as follows: with the increase of altitude, atmospheric pressure decreases; Within the range of 3000M, every time the air pressure increases 12M, the air pressure decreases 1mmHg, which is about 133Pa! 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.