What's the difference between hot summer and hot summer?

The difference between light summer heat and heavy summer heat is about 15 days.

The summer heat lasts from July 6th to July 7th or 8th in the Gregorian calendar every year, and the summer heat lasts from July 22nd or 23rd or 24th every year, so the difference is about15th day. 24 solar terms adopts the method of "fixing qi", that is, on the ecliptic with a circumference of 360 degrees (the apparent path of the sun on the celestial sphere for one year), it is divided into 24 equal parts, and every 15 is 1 equal part, so the interval between two solar terms is about 15 days.

Extended reading:

The current "twenty-four solar terms" come from the "fixed air method" formulated by western priests more than 300 years ago (according to the longitude of the sun), and it has been used ever since 1645. However, the "lunar calendar" and "twenty-four solar terms" from the time when the western priests formulated the constitutional calendar were determined according to the position of the sun on the ecliptic (the degree of the longitude of the sun), that is, on a 360-degree circle "ecliptic" (the apparent path of the sun on the celestial sphere for one year), it was divided into 24 equal parts, one for each 15. That is, the sun starts from the vernal equinox, that is, the longitude of the Yellow River is zero. At this moment, the sun shines vertically on the equator, and every advance of 15 degrees is a solar term; A week after the operation, I returned to the vernal equinox, which is a tropical year, and the 24 solar terms are exactly 360 degrees. Every time the sun moves 15 degrees on the ecliptic, it is a "solar term", and the degrees between each "solar term" are equal (the time is different), which is called "the method of regulating qi".

In the twenty-four solar terms, the activity law of the sun's direct point is: at the vernal equinox, the sun's direct point is at the equator 0, and then moves north; During the summer solstice, the direct point of the sun is on the Tropic of Cancer (23 26' n), and then moves south. At the autumnal equinox, the direct point of the sun is 0 on the equator, and then it continues to move south; During the winter solstice, the direct point of the sun is on the tropic of Capricorn (23 26), and then it moves northward. Twenty-four solar terms are 24 time points, and when the "point" falls is the natural result of celestial movement. The solar terms (according to the degree of the yellow meridian) divided by the method of "fixing qi" began in the beginning of spring and ended in the great cold. The current 24 solar terms take the earth's revolution around the sun as a cycle, which basically summarizes the different positions of the sun on the ecliptic at different times of the year, the exact time of cold coming and summer going and the laws of natural phenomena.

The Gregorian calendar dates in 24 solar terms are roughly the same every year: the first half of the year is around 6th and 2 1, and the second half is around 8th and 23rd.

Transfer from: Weather Network