What is the origin of the summer solstice solar terms?

Solstice is the earliest of the 24 solar terms. In the 7th century BC, the shadow of the sun was measured by civil soil gauge, and the summer solstice was determined.

High temperature, high humidity and occasional thunderstorms are the weather characteristics from summer to the future.

The summer solstice is in midsummer, that is, at noon, belonging to the sun; Although summer is full of yang and the daytime is the longest, it is not necessarily the hottest day of the year, so the heat near the surface is still accumulating and has not reached the maximum.

The summer solstice is not only one of the 24 solar terms, but also a festival in the ancient "four seasons and eight festivals". Since ancient times, people have the custom of worshipping gods and ancestors in the summer solstice.

In addition, after the summer solstice, people generally drink Qingbuliang soup, herbal tea and sour plum soup to escape the heat.