What are the grades of rainfall?

Rainfall levels are divided into seven levels: micro-rainfall, light rain, moderate rain, heavy rain, rainstorm, torrential rain, torrential rain and torrential rain.

Rain refers to the weather phenomenon that condensed water vapor in the atmosphere falls to the surface of the earth in different ways. The principle of rainfall is that the water on the earth is turned into water vapor after being irradiated by sunlight and evaporated into the air. Water vapor condenses into small water droplets when it meets cold air at high altitude. And then turn into raindrops.

Almost all water vapor in the atmosphere is concentrated in the troposphere. The higher the temperature, the more water vapor the atmosphere can hold, and vice versa. At a certain temperature, when the air can't hold more water vapor, it is called saturated air. When the water vapor in saturated air matches the temperature, there will be no water vapor condensation, but when the air reaches the supersaturated state, excessive water vapor will be generated and water vapor condensation will occur.

Rainfall type

Convective rain: local heating of near-surface air or strong cooling of high-altitude air leads to convection between upper and lower air, which makes lower air rise and water vapor cool and condense at high altitude, also called thermal thunderstorm. Strong convective rain may be accompanied by strong winds, thunder and lightning, hail or tornado, but the rainfall time is short, the rain area is small, or it is distributed in discontinuous bands.

Topographic precipitation: when the moist air mass moves forward, it is blocked by high mountains, and the airflow is forced to rise slowly, resulting in adiabatic cooling and condensation. The rainfall thus formed is called topographic precipitation. Topographic precipitation mostly falls on windward slopes (windward slopes), and leeward slopes are adiabatic heated due to air subsidence, thus reducing cloud cover and rainfall.

Typhoon storm: Typhoon storm is rain brought by storms in tropical oceans. This kind of storm is composed of an unusually strong hot and humid air mass in the ocean. Where the typhoon passes, the rainstorm is fierce, which can reach hundreds of millimeters at a time, and sometimes it can reach more than 1000mm, which is very easy to cause disasters and is called typhoon storm. Typhoon will not only bring strong winds, but also bring precipitation.