How to calculate the intersection time of the 24 solar terms?

Modern people accurately determine the specific time of the 24 solar terms according to the position of the sun on the ecliptic.

The current 24 solar terms are divided by the method of "fixing qi". Depending on the sun starting from the vernal equinox (longitude zero, at this moment the sun shines vertically on the equator), every advance of 15 degrees is a solar term; After a week's operation, I returned to the vernal equinox, which is a tropical year with 360 degrees, so it is divided into 24 solar terms.

Date calculation:

The general formula of the birthday girl-[y× d+c]-L.

Y = the last two digits of the year, d = 0.2422, l = the number of leap years, and C depends on the solar terms and year.

265438+C value in the early spring of 20th century = 3.87.

For example: beginning of spring date 20 17.

[ 17×0.2422+3.87]-[( 17- 1)/4]=7.9874-4=3。

So the beginning of spring date of 20 17 is February 3rd.

The "twenty-four solar terms" are divided by the "fixed air method", that is, each solar term corresponds to a certain position that the earth reaches every time it runs 15 on the ecliptic; The method of "fixing qi" divides the sun's annual movement track into 24 equal parts, each equal part is 15, and each equal part is a solar term, which starts from beginning of spring and ends with severe cold.

"Twenty-four solar terms" express the unique concept of time between human beings and the natural universe, and contain the long-standing cultural connotation and historical accumulation of the Chinese nation.

Twenty-four solar terms are not only the time criterion promulgated by successive governments, but also the compass to guide agricultural production and to predict cold, warm, snow and rainy days in people's daily life. In the field of international meteorology, the 24 solar terms are known as "the fifth invention of China". 2016165438+1October 30th, 24 solar terms were officially listed in UNESCO's Representative List of Intangible Cultural Heritage of Humanity.