How is the "Double Spring Year" determined?

The double spring year means that there are two solar terms in beginning of spring in a year. The double spring year is a unique phenomenon in China's commemorative calendar, which is actually caused by the "error between the solar calendar and the lunar calendar"

The solar calendar is based on the law that the earth revolves around the sun. The earth rotates once a year and is divided into twelve months, which is 365 days (366 days in leap years). The lunar calendar is based on the laws of the moon's profit and loss. It takes the moon around the earth as a month and a year as twelve months. The actual number of days is 354 days.

China's calendar is based on the cycles of the sun and the moon. In this way, there is an eleven-day deviation between the lunar calendar and the solar calendar, so the lunar calendar has a "leap month" to solve the time difference problem of the lunar calendar.

The double spring year means that there are two solar terms in beginning of spring in a year. The double spring year is a unique phenomenon in China's commemorative calendar, which is actually caused by the "error between the solar calendar and the lunar calendar"

The solar calendar is based on the law that the earth revolves around the sun. The earth rotates once a year and is divided into twelve months, which is 365 days (366 days in leap years). The lunar calendar is based on the law of the moon's profit and loss. It takes the moon around the earth as a month and a year as twelve months. The actual number of days is 354 days.

China's calendar is based on the cycles of the sun and the moon. In this way, there is an eleven-day deviation between the lunar calendar and the solar calendar, so the lunar calendar has a "leap month" to solve the time difference problem of the lunar calendar.