What does it mean to divide the summer heat into three periods in ancient China?

The ancients divided the great summer heat into three periods, namely: "a rotten grass is a firefly;" Second, wait for the soil to moisten and cool off the heat; It will be fine when it rains. " Summarize the corresponding phenological phenomena in each period, that is, the "reactions" in the three periods of great summer heat, including animal reactions, plant reactions and natural phenomenon reactions.

After a while, the rotten grass turned into a firefly. "Gewulun" said: "Fireflies are transformed from rotten grass and rotten bamboo roots." Also known as jack-o 'lantern. In fact, rotten grass for fireflies is about campfire insects laying eggs. Fireflies usually lay their eggs on grass roots near the water surface in summer, and the larvae are buried and pupated, and then become insects in the next spring. The ancients mistakenly thought that fireflies were changed by rotten grass itself, which was just an illusion in their eyes.

Second, the soil is hot and humid. In the Book of Rites, it is said that "the soil moistens the summer heat", that is, the soil is infiltrated and the air is hot and humid-the rainfall is large, the soil and air are moist and the temperature is high, which is the moment when crops grow wildly. Summer, or humid summer, refers to midsummer.

Third, when it rains heavily. Yizhoushu said: "The earth moistens the summer heat. In five days, it will rain cats and dogs, "he said." It rains sometimes, and the country is ungrateful. " The summer heat is the period with the most sunshine and the highest temperature in the basin in a year. It is also the period with the most rain, the most common thunderstorm and the most concentrated and frequent high temperature days in the west of the basin. Therefore, summer is also the season of thunderstorm weather.