What is the concept of precipitation of 200 mm?

200 mm of precipitation reached a rainstorm.

For example, the area of an acre of land is 666.7 square meters, and the rainfall of 1 mm is equivalent to watering an acre of land with 0.6667 cubic meters or 666.7 kilograms of water. For another example, Zhengzhou covers an area of 7,500 square kilometers, and the rainfall of 200mm per hour is 65.438+0.5 billion cubic meters, which is equivalent to pouring 654.38+0.50 West Lake water into Zhengzhou in one hour.

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1. The precipitation per unit area in the rainfall area is the average value calculated from the rainfall measured at several observation points in the rainfall area, which is equivalent to the water depth of the total rainfall in this rainfall area without infiltration or loss at all and evenly distributed on the ground.

2. The amount of rainfall is not determined by the size of raindrops that our eyes see in a short time. Generally, the intensity and size of precipitation are compared by the thickness of water layer accumulated by precipitation in the same time.

1) Meteorologically, the precipitation level is divided according to the rainfall within 24 hours. Light rain means that the precipitation is within 10 mm; Moderate rain means that the precipitation is between 10-25mm. Heavy rain means that the precipitation is between 25 and 50 mm, heavy rain means that the precipitation is between 50 and 100 mm, and heavy rain means that the precipitation is between 100 mm and 200 mm.

The torrential rain refers to the rainstorm with the precipitation of more than 200mm, and the shower refers to the formative precipitation, with large raindrops, uncertain falling and stopping, and drastic changes in intensity. When it rains, it is dark, sometimes it suddenly clears up, revealing sunny days, and sometimes it is accompanied by thunder.

2) The largest rainstorm in the world occurred in reunion island, South Indian Ocean, with a 24-hour rainfall of1.870mm, and the largest rainstorm in China occurred in Xinliao, Taiwan Province Province, with a 24-hour rainfall of1.672mm.

3. Difficulties in numerical weather forecasting. First, the equations of atmospheric motion are mixed in scale, and the system from hundreds of meters to tens of thousands of kilometers uses a set of hydrodynamic equations, so it is very easy to be unstable. Another point is that the amount of calculation is extremely huge. Even if the supercomputer develops to E level, the numerical prediction system will soon be unable to keep up with the supercomputer as long as the resolution is slightly adjusted. When China began to develop numerical weather forecasting experiments in the late 1950s, it used a simplified version.