Calculate the number of days by Gregorian calendar

"V" means that it is too hot to lie still. The dog days are calculated according to the lunar calendar, which is from mid-July to early August in the solar calendar. The lodging time is not fixed every year, and the length of lodging time is also different. You need to look up the almanac to calculate, and the date of lodging can be simply expressed by the formula of "three Geng on the summer solstice" Starting from the summer solstice, the third Geng day is the first Geng day, the fourth Geng day is in the middle, and the 1 th Geng day after beginning of autumn is the last Geng day.

According to the China lunar calendar, from the summer solstice, the number of volts falls on the third Geng day of the lunar calendar, and it is also stipulated that the first Geng day after beginning of autumn is the beginning of dog days. In this way, the intermediate period is sometimes ten days and sometimes twenty days. Generally speaking, there are about 45 days between the summer solstice and beginning of autumn. If there are four Geng days in this period, the middling period is ten days, and if there are five Geng days, the middling period is twenty days. This situation is caused by the rule that the last crouch must be started after the beginning of autumn.

Under normal circumstances, the summer solstice is on June 22nd, but the cycle of a tropical year is about 365 days plus 6 hours. Therefore, the summer solstice fluctuates around June 22, usually between June 26 and June 23. No matter how the summer solstice fluctuates, the date of several volts in the next year can only be advanced or postponed by 5 days (6 days in advance or 4 days in leap year). The following table gives the date of several volts in the next few years.

age

Summer Solstice

The first day of collapse

Beginning of Autumn

The end of Volt has begun.

20 12

June 2 1

July 18

10 days

August 7

August 7

20 13

June 2 1

July 13

20 days

August 7

August 2002 65438

20 14

June 2 1

July 18

10 days

August 7

August 7