How many types of rain do you know?

When chatting with a friend , Talk about the type of rain , I should have talked about geography in school , however , Now I forgot , So I found some information , Maybe I'll go to school in the future , Will encounter this .

If it comes to rain , And cloud , Scientifically speaking , Cloud is the premise of rain .

When the ocean 、 lakes 、 Water molecules in rivers come from a heat source ( Like the sun ) Get extra energy at , It will turn into steam , Take the energy you absorb into the air , The remaining liquid water is cooled by the loss of energy , The whole process is evaporation , This is the beginning of the cloud story .

The capacity of air for water vapor is not infinite , Within a certain area , When its capacity for water vapor reaches an extreme value, it is called saturation . This extreme value changes dynamically , Depends on the temperature and pressure of the air ( That is, the weight of air ), Higher temperature 、 The greater the air pressure , The more water vapor the air can hold . When the water vapor in the air reaches saturation, the air will not stretch , The extra steam will liquefy into water droplets or condense into ice crystals , Then clouds began to form . In the process , Other tiny particles in the air, such as dust 、 Bacteria and even volcanic ash are involved , Provide contact surface for the liquefaction or condensation of water vapor . Final , A large number of water droplets or ice crystals converge to form clouds .

Then why do clouds float in the sky ？

In fact, water droplets or ice crystals that converge into clouds are also affected by gravity , And they float in the air and don't fall because of the wind , The wind lifts and moves them . When these cloud drops are enough and heavy , It will fall and form precipitation .

therefore , Cloud is the premise of rain , The key to cloud formation is the saturation and liquefaction of water vapor in the air ( Or Ninghua ), This is also the key to understanding the causes of rain . As mentioned earlier , The threshold of water vapor saturation in air is affected by both pressure and temperature , If the air pressure remains constant , When the temperature drops , The threshold of saturation also decreases , This is the main cause of cloud and rain , That is, when it is cold , Although the temperature is constant, the air can reach saturation after absorbing enough water vapor , But the former is in the majority .

Strictly speaking, there should be convective rain 、 Terrain rain 、 Frontal rain 、 Taiwan Wind and rain . But if according to the different cooling methods , There are three main causes or types of rain , These are the first three .

1、 Convective rain (Convective Rain)

In the sunshine , When the air is strongly heated , A lot of warm water vapor from the ocean 、 Land escapes into the air , In the process of rising, they condense into water droplets when they encounter cold / Ice crystals then become clouds and rain . Convective rain is usually rapid , The coverage area is also relatively limited . This type of thunderstorm is common in summer , Rain in tropical areas also belongs to convective rain , The equatorial region is dominated by convective rain throughout the year , Convective rain in our country is often seen in summer afternoons .

2、 Terrain rain (Orographic Rain)

When the hot and humid air meets the obstruction of the mountain, it will be forced to climb up the hillside , In the process of rising , The water in the air cools and condenses to form precipitation , Clouds and rain basically form on the windward side near the top of the mountain , The vegetation on this side will also be more lush , The airflow falling along the leeward side after climbing the top of the mountain is drier due to the loss of water vapor , The temperature is also higher , This part of the area is therefore called rain shadow (Rain Shadow). For example, the precipitation in Northeast India and Southeast Tibet of China .

3、 Frontal rain (Frontal Rain)

If the temperature of a large mass of air 、 Humidity is relatively evenly distributed in the horizontal direction , It is called air mass (Air Mass), When the cold air mass meets the warm air mass , It will form a front (Front). Two air streams with different properties meet , The interface between them is called frontal . The so-called cold front is that the cold air mass grabs the position of the warm air mass , Force 、 Lift lighter 、 More bulky heating mass along ( A hypothetical ) Frontal climb , The warm front is that the warm air mass actively approaches the cold air mass , And then climb up along the front of the warm front . Whether the warm front or the cold front , It is the heating mass that liquefies into clouds and rain when it is cold in the process of rising . Because the cold air mass moves faster , So Leng Feng ( Cold catches up with warm ) Compared with the warm front ( Warm chasing cold ) It will move faster , Usually, the rainfall produced by the cold front will be more rapid , And the rainfall formed by the warm front will be more lasting .

4、 Taiwan Wind and rain (Typhoon Rain)

A special form of rainfall , It usually happens when a typhoon comes , The wind is usually strong in the center of a typhoon , Up to 12 magnitude , The time of rainfall generally depends on the speed of the typhoon , The rainfall intensity is very high in a short time , And accompanied by strong lightning and strong wind . A special case is , The sky in the area where the eye of the typhoon passes is very calm , When the eye of the typhoon comes , There will be very brief sunny days in this area, and the strong winds will also weaken briefly .

besides , Let's watch the weather forecast , Sometimes it comes to rainstorms . The definition of Rainstorm in China's meteorology , In order to 24 The total hourly rainfall reaches 50mm The above is standard . But the rain is 24 Different distributions within hours will give people a very different feeling . for example ,50mm If rainfall is evenly distributed in 24 Hours , It feels like drizzle , But if precipitation occurs in a short time , It will give people the feeling of a torrential rain .

Rainstorm definition standard ,

(1) 24 The hourly precipitation is greater than or equal to 50mm The precipitation is called rainstorm , This is the most common rainstorm , Standing in the rain is similar to soaking in the rain with a shower .

(2) 24 The hourly precipitation is greater than or equal to 100mm The precipitation is called heavy rain , It's equivalent to countless mineral water bottles watering you .

(3) 24 The hourly precipitation is greater than or equal to 250mm The precipitation of is called torrential rain , The ultimate big in the rainstorm BOSS.

Reference material ,

1. https://www.bilibili.com/read/cv12810968

2. https://sciencetrends.com/the-types-of-rain-clouds/

3. https://www.3dgeography.co.uk/why-does-it-rain

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