Is the leap month in the lunar calendar once every four years? Is there anything particular about the specific leap month? Is it regular?

As a kind of China lunar calendar, the number of days in each month depends on the monthly loss, and the time of one year is based on 12 months, which is about 1 1 day less than one return. In order to close the earth's orbit around the sun, that is, the tropic year, one month is added every two to four years, and the added month is a leap month. The year with leap month is 13 months, and the calendar year is 384 or 385 days. This year is also called leap year.

The calendar takes the moon as the cycle (lunar calendar), and the December calendar is about 354 days in total; Combined with the almanac (solar calendar), the almanac is compiled according to the four-season cycle formed by the revolution of the earth. The monthly calendar is shorter than the annual calendar by 1 1 day. Therefore, it is necessary to add 7 leap months every 19 years to make up for the error. Deciding which month is a leap month depends on 24 solar terms. Lunar months usually include a solar term and a neutral atmosphere, such as the autumnal equinox. If a lunar month has only solar terms but no neutral atmosphere, one more month will be added to the calendar as a leap month. Taking 2006 as an example, July of the lunar calendar happened to be a month with solar terms but no neutral atmosphere, so there was an adjustment error in July.