Precipitation forecast

In the prediction of precipitation, the probability of precipitation is generally expressed, and the probability of not using it is generally 100%, because scientists are only 70% sure about whether precipitation is possible or not. Probability is a mathematical term, and its intuitive meaning refers to the possibility of a thing happening. The prediction published in the form of probability is called probability prediction. If we are 70% sure whether it will rain, the weatherman will tell everyone that it will rain today. The general situation of precipitation probability forecast is sunny, and the probability of 0% is impossible to precipitation; Sunny to cloudy, the probability of precipitation between 10% and 20% is very small; Cloudy, sporadic or local precipitation, when the probability is between 30% and 50%, there is a chance of precipitation; Precipitation, the probability is between 60% and 70%, and the possibility of precipitation is relatively large; When it is greater than or equal to 80%, the possibility of precipitation is high; If the probability is 100%, there will definitely be precipitation. The meteorological department calls it rain and snow precipitation, and precipitation is called precipitation. The unit of precipitation is usually millimeters. 1mm precipitation refers to the water depth per unit area1mm. 1mm How much precipitation falls into the field? The area per mu is 666.7m2, so 1mm precipitation is equivalent to an increase of 0.667m3 of water per mu. Every cubic meter of water is 1000 kg, and the precipitation of 1 mm is equivalent to pouring about 667 kg of water on each mu of land.

Since 13, the annual precipitation in Beijing has exceeded 700 mm for the first time, and it is expected to be rated as "the top ten weather and climate events at home and abroad in 201year". Yesterday, the China Meteorological Bureau announced that the average annual precipitation in China this year hit a new low in 60 years. Up to now, the national average precipitation is 544.6 mm. ..

According to the relevant person in charge of China Meteorological Bureau, historically, there was a lot of precipitation in Beijing in 1960s, but in the past decade, especially since 1999, the annual precipitation in Beijing rarely exceeded 500mm. This is also the main reason why this event was selected as "Top Ten Weather and Climate Events at Home and Abroad in 20 1 1 Year".