What's the difference between high pressure and low pressure?
Definition of gas pressure:
The pressure generated by the movement of air molecules in any surface unit area. P=F/S air pressure is expressed in hectopascals (hPa), with one decimal place reserved.
Commonly used units:
A unit of air pressure, usually the height of a mercury column. For example, a standard atmospheric pressure is equal to the weight of a 760mm high mercury column, which is equivalent to bearing an atmospheric pressure of 1.0336kg in an area of one square centimeter. Because the weight and length units used in different countries are different, and the pressure units are not uniform, it is not convenient to compare and analyze the global pressure. Therefore, "hectopascals" are used as the air pressure unit in the world. After conversion:
A standard atmospheric pressure =1.013 *10.5 Pa (millibar).
1 mm Hg height =4/3 hectopascals (millibars)
1 standard atmospheric pressure = 760mmhg height.
Reasons for formation:
According to the theory of molecular dynamics, the pressure of gas is caused by the frequent collision of a large number of molecules with the container wall. The impact time of a single molecule on the container wall is very short, and the effect is discontinuous, but a large number of molecules frequently collide with the container wall, and the force on the container wall is continuous and uniform. The ratio of this pressure to the wall area of the container is the pressure.
On the same horizontal plane, if the air pressure distribution is uneven, the air will flow from the high pressure area to the low pressure area. Therefore, the air pressure in a certain area is high, and the air in this area flows out in the horizontal direction. 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.
High pressure:
Short for "high pressure", it refers to the place where the air pressure is higher than the surrounding area, and the place with the highest air pressure is called "high pressure center". At the same height, the atmospheric vortex with the central air pressure higher than the surrounding air pressure is called "high pressure" or "high pressure" for short. Usually, the high pressure near the ground is studied.
Low air pressure:
The air pressure we study is relative. Comparing the air pressure in a certain area with its surroundings, the place with the lowest air pressure is called the "low pressure center". The air in the surrounding areas with higher air pressure will flow to the center, just like the water in the surrounding mountains will gather in the center of the basin. Near the center of low pressure in the northern hemisphere, the wind blows to the center, which is a left-handed vortex, and the blown air rises upwards to form an updraft, usually because of bad weather.