Will it rain with a 55% probability of precipitation?

Precipitation probability refers to the probability of rain in a certain area today. The probability of rain is this number within the forecast time and regional scope. It can also be understood that the accuracy of this forecast in the specified time and area is this number. The probability of precipitation is 55%, which means the probability of rain or snow is 55%. If the accuracy of weather forecast is 55%, then the probability of precipitation tomorrow is 55%. This probability is usually very high.

This kind of weather forecast using probability has been used since 1966 in the United States, 1980 in Japan and 1995 in China. Forecasters often broadcast on TV (or show it on the weather forecast), for example, the probability of precipitation today is 70%.

The ancients' methods of forecasting the weather

In the book After Fei Yi, there is a relatively complete exposition: whoever is waiting for rain, who looks at the four blocks with gloomy chords, should rain. For example, bullfighting is like a storm, with different clouds like buffaloes. It didn't rain for three days, the rain was dark and the clouds were as thin as rafters. On the fifth day, the sun and the moon are covered, and it will rain. The clouds are like two people holding drums and forks, and they are all heavy rains. This passage vividly describes the shapes of cumulus clouds, stratocumulus clouds and cirrus clouds, and the conclusions about the influence of these clouds on the next day's weather are also accurate. The emergence of these theories also provides guidance for the work of ancient farmers.

In addition to observing the shape of clouds, the ancients also predicted the future weather according to the movement of clouds. There is a folk saying that clouds travel east, chariots and horses wear them, clouds travel west, horses splash mud, clouds travel south, water rises in the pool, and clouds travel north, which is good for drying wheat. Is a typical example. In fact, the ancients judged the wind direction by the direction of clouds, thus playing a role in forecasting the weather.