What day is leap month?

Leap month does not refer to which months, but there are two identical months in the lunar calendar.

The so-called leap month is an extra whole month in a year. This is to coordinate the contradiction between the tropic of Capricorn and the Han calendar, and to prevent the month of the Han calendar from being out of touch with the tropic of Capricorn and the four seasons. Set 1 leap month every two to three years. In other words, there will be 13 months in a year in the new calendar, and the calendar that is conducive to agricultural activities after this situation is the lunar calendar. The leap month is created to coordinate the contradiction between the lunar calendar and the solar calendar.