"Leigong sings first, there is not much rain." This proverb was summed up by our ancestors from their life practice. It means: thunder before it rains, and the rainfall will not be very heavy. Maybe it just disappeared with a gust of wind.

In terms of meteorological science popularization, in summer, citizens often find clouds such as castles and mountains not far from the sky, and thunder comes from time to time in the distance. Meteorology calls this kind of cloud "cumulonimbus" or "cumulonimbus". During lightning, there is a strong vertical thermal convection movement in the atmosphere below the clouds. Because the range of thermal convection is not large, or only affected by topography, the spatial range of cloud system is very small, usually only a few kilometers to dozens of kilometers, so there is no water vapor supply and no energy supplement. Therefore, most of these thermal thunderstorms and topographic thunderstorms are self-destructive, and there can be no heavy precipitation. This is the truth that "Lei Gong sings first, and it doesn't rain much".

On the contrary, "after the rain clears, it is followed by heavy rain." This shows that there is a large range of frontal cloud system rainfall, and the rainfall is very large. Because the cloud is rich in water vapor and heat energy supply, lightning is more intense, and there may be ground lightning, which is more helpful to rainfall. Lightning strikes often occur in this weather.