What is the double start of spring?

There are two beginning of spring in the lunar calendar.

"Double beginning of spring" and "Year without beginning of spring" are both concepts in the lunar calendar, which refer to a year with "Double beginning of spring" or no "beginning of spring" throughout the year. This is because some years are shorter than the Tropic of Cancer and some years are longer than the Tropic of Cancer.

In life, we will hear different views of the lunar calendar, the solar calendar and the lunar calendar. The lunar calendar is a calendar arranged according to the change of the moon phase, and a cycle of the change of the moon phase is called the new moon; The solar calendar is a calendar based on the earth's orbit around the sun, and the time for the earth to orbit around the sun is called the tropic year.