What is a weather system?

Weather system refers to the atmospheric motion system with typical characteristics, such as high pressure, low pressure, high pressure ridge, low pressure trough, etc., which causes the change and distribution of weather. Meteorological satellite observation data show that in the process of atmospheric movement, large and small weather systems are intertwined, interactive and constantly evolving.

Weather system refers to a specific system of flow field, pressure field, temperature field and humidity field, or a specific weather phenomenon that has an important influence on weather formation. The flow field includes waves, cyclones, anticyclones, shear lines, convergence zones, typhoons, rapids, squalls and tornadoes. The pressure field includes low pressure, high pressure, low pressure trough and high pressure ridge; The temperature field has air masses and fronts; There are dry areas, wet tongue and dew point front in the humidity field. The combination of meteorological elements includes cold high pressure, hot low pressure, cold trough, warm ridge and energy front. Weather systems for specific weather phenomena include thunderstorms, hail and clouds.

The weather system is always reborn, developing and dying. Various weather systems have different birth and death conditions and energy sources. Even if the characteristic scales belong to the same system, their birth and death conditions and energy sources are different. For example, the development conditions of extratropical cyclones are mainly determined by the intensity of air divergence caused by vorticity advection over them, and its energy comes from the effective potential energy stored in atmospheric baroclinic. The occurrence and maintenance of typhoon is due to the release of latent heat by tropical disturbance, which is related to the potential instability and convection instability of tropical atmosphere. Its energy mainly comes from the latent heat released by the water vapor supplied by the ocean during condensation.