How to judge solar terms?

This is to judge the seasons and solar terms, as well as related folk festivals and customs from the change of the position of the direct point of the sun.

There are three related knowledge points in this type of question. First, the revolution of the earth and several special positions; Second, knowledge about seasons and solar terms; Third, folk festivals and customs related to seasons and solar terms.

When doing this kind of problem, we should first judge the season according to the special position of the earth's revolution. The picture shows "two solstice days" and "two minute days". When the sun shines directly at the equator, it is two minutes a day; When the sun shines directly on the Tropic of Cancer, it is the second solstice. Among them, the Tropic of Cancer refers to the summer solstice; When the tropic of Capricorn is in direct contact, it is the winter solstice. Coupled with the direction of the earth's movement in the orbit of revolution, it is easy to judge the season. As shown below.

Look at the topic again and compare the picture given in the topic with the picture below. We can see that point D is the vernal equinox and point A is the summer solstice.

Then judge the solar terms. The twenty-four solar terms and their order must be remembered. Such as the following song "Twenty-four solar term song":

"(Li) Spring rain (water) scares (stings) spring (minutes) clear (bright) valley (rainy) days,

(vertical) summer (small) full of awns (species) summer (to) summer (referring to small summer and big summer);

(vertical) autumn (summer) (white) dew autumn (minute) cold (dew) first frost,

(Li) Winter (small) snow (big) snow winter (to) small (cold) cold. "

In the four sentences, each sentence represents a season, and each sentence has six solar terms, starting from "beginning of spring", "Changxia", "beginning of autumn" and "beginning of winter" and ending at the corresponding season. Among them, the four solar terms related to the four special positions of the earth's revolution, such as "vernal equinox" and "the second solstice", are located in the middle of the four sentences, which is easier to remember.

During the movement of the earth from point D to point A, the direct point of the sun gradually moves northward from the equator to the Tropic of Cancer, and the season in the northern hemisphere changes from spring to summer, from mid-to-late March to mid-to-late June.

There are five solar terms during this period: Qingming, April 4-6; Grain Rain, April19-21; Long summer, May 5-7; Xiaoman, May 20-22; Mangzhong, June 5-7.

Folk festivals and activities related to the above solar terms include "Tomb-Sweeping Day" and "Dragon Boat Festival", which are held on April 5th of the solar calendar (after the vernal equinox15th day) and around the fifth day of the fifth lunar month.

The main folk activities in Tomb-Sweeping Day are: ancestor worship, grave sweeping, outing and flying kites.

The Dragon Boat Festival is also called Duanyang Festival. The main folk activities are: eating zongzi and racing dragon boats.

You can choose from the options given.