How many millimeters of rainfall is calculated?

Rain falls from the sky to the ground without evaporation, infiltration and loss. The depth of water layer accumulated on the water surface is called rainfall (in millimeters), which can directly indicate the amount of rainfall.

At present, the commonly used instruments for measuring rainfall are rainfall cylinder and measuring cup. The diameter of the rain tube is generally 20 cm, and it is equipped with a funnel and a bottle. The measuring cup has a diameter of 4 cm and is used together with the rainfall tube. When measuring, pour the rainwater in the rainfall cylinder into the measuring cup, and you can know the rainfall of the day according to the scale on the cup.

How many millimeters of rainfall reaches generally refers to precipitation.

First, the concept of precipitation:

Precipitation refers to the depth at which liquid or solid (after melting) water falls from the sky to the ground and accumulates on the horizontal plane without evaporation, infiltration and loss. In millimeters, meteorological observation takes one decimal place.

Second, the form of precipitation:

According to different physical characteristics, precipitation can be divided into liquid precipitation and solid precipitation. Liquid precipitation includes rain, rainstorm, thunderstorm, freezing rain and showers in Mao Mao. Solid precipitation includes snow, hail and graupel. And liquid-solid mixed precipitation such as sleet.

Third, the precipitation distribution:

The general distribution trend of annual average precipitation in China is gradually decreasing from southeast to northwest. The average annual precipitation in China is between 494.9mm- 173.0mm, and the precipitation is mainly concentrated in summer, and the rainy season and dry season are distinct. The distribution of annual precipitation in China is mostly concentrated in May-September, accounting for more than 90% of the annual precipitation, and the warm season (June-August) can account for about 70% of the annual precipitation.

Due to the heating effect of complex underlying surface on air, air stratification is unstable, which easily leads to thermal convection and formation precipitation. At the same time, due to high altitude and low temperature, precipitation is mainly in solid form and matrix precipitation. In addition, it is more at night, accounting for more than 50% of the total.

Extended data

The main factors affecting precipitation are ① the development of weather system. The intersection of warm and humid air and cold air promotes the sunspot effect, which makes warm and humid air forced to rise by cold air or climb along the front slope by warm and humid air. ② In summer, local thermal convection makes warm and humid air rise with strong convection, forming small cumulonimbus clouds and thunderstorms. (3) The ups and downs of the terrain force the windward slope to rise, but this is a relatively minor factor. In most cases, it is combined with the first two processes and affects the geographical distribution of precipitation.

The place with the most and least precipitation in China, the highest annual precipitation record in China is Huoshaoliao, Taiwan Province Province, with an average annual precipitation of 6,558 mm and a maximum annual precipitation of 8,409 mm. The place with the least annual precipitation is Toksun, Turpan Basin, with an average annual precipitation of only 5.9 mm, and the annual precipitation days are less than 10 day. In some years, there is not a drop of water.

In Turpan, cross-shaped hollow adobe houses are common on both sides of highways. This is a special "baking room" for raisins. In a dry and rainy climate, grapes can be naturally dried in a "drying room". The world-famous Turpan raisins do just that.

In one day, the precipitation above 50 mm is heavy rain, the precipitation above 25 mm is heavy rain 10-25 mm is moderate rain 10 mm is light rain, the precipitation below 75 mm is heavy rain, and the precipitation above 200 mm is heavy rain. The general distribution trend of annual average precipitation is gradually decreasing from southeast to northwest. The average annual precipitation in China is between 494.9 mm 173.0 mm. ..

Precipitation is mainly concentrated in summer rainy season and dry season. The distribution of annual precipitation in China is mostly concentrated in May and September, which can account for more than 90% of the annual precipitation, and the warm season (June) can account for about 70% of the annual precipitation.

Due to the heating effect of complex underlying surface on air, air stratification is unstable, which easily leads to thermal convection and formation precipitation. At the same time, due to high altitude and low temperature, precipitation is mainly in solid form and formation precipitation. In addition, nighttime accounts for more than 50% of the total.

References:

Baidu precipitation encyclopedia