Why are there no leaps in the eleventh, twelfth and first months of the lunar calendar?

Because the speed of the earth's revolution is relatively fast in winter, there are few phenomena in November, twelfth month and first month of the lunar calendar that only solar terms have no gas.

The specific reason may start with what is leap month.

Leap month refers to a month added to every leap year in the lunar calendar. The lunar calendar has a leap in three years, two leap in five years and seven leap in nineteen years. Every month in a leap year is called a leap month. A leap month is called a leap month after a certain month. The real reason is that our lunar calendar is based on the moon circling the earth once a month, and there will be a new moon every week, that is, the first day of the lunar calendar is missing, and 1 1 month is full. But the time of the moon revolution 12 circle (about 355 days) is not equal to the time of the earth revolution around the sun axis. In order to correspond to the solar terms and arrange agricultural production activities, a leap month was created to supplement this time difference.

So what is the principle of corresponding solar terms? The twenty-four solar terms completely reflect the position change of the direct point of the sun. The twenty-four solar terms are the solar calendar, which is divided into twelve solar terms and twelve solar terms. Each month of the lunar calendar must correspond to one of the 24 solar terms and one of the neutral qi. If a month's solar terms are at the beginning of the month, but neutral words fall in the next month, a leap month must be set up, so that this month can have both solar terms and neutral words. This can ensure that the calendar reflects the movement and changes of the moon.

Talking about the correspondence between months and solar terms, we can know why there are fewer leap months in winter and more leap months in summer. Because in winter, the speed of the earth's revolution is faster. In November, the twelfth lunar month and the first lunar month, there are few solar terms, but in summer, the speed of the earth's revolution is relatively slow. Among the 24 solar terms, the interval between every two solar terms is longer, and there are more leap months in summer.