What is a "spring-free year"?

There are 199 1 Year of the Sheep, 1997 Year of the Ox, 2000 the Year of the Loong, 2005 Year of the Rooster and 20 10 Year of the Tiger. "No spring year" refers to a year in which there is no beginning of spring in the whole year of the lunar calendar. In order to adapt to the changes of cold and summer, the ancients added seven leap months every 19 years in the lunar calendar, resulting in no beginning of spring for seven years in 19 years.

China's traditional calendar summer calendar is a combination of yin and yang: "Yin" means that the average length of its calendar month is 29.5306 days, and the first day of each month is the first day; "Yang" refers to the Spring Festival, which is based on the tropical year and takes the first day of the first month around beginning of spring every year as the first day of the first month of the year. /kloc-the average lunar year of 0/2 months is only 354 or 355 days, and some years are only 353 days. A leap month 13 year has 383 or 384 days, and some years have 385 days, which can contain 25 solar terms, so that there is a beginning of spring at the beginning and end of each year, which becomes a "double spring year", while the next year has only 23 solar terms, so there is no "beginning of spring" and it becomes a "spring-free year".

There is no "beginning of spring" in the whole year, and there will be seven times in 19. For example, there is no spring in the Year of the Monkey, the Year of the Pig, the Year of the Ox, the Year of the Loong and the Year of the Sheep.