What are the three stages of solar terms?

According to our calendar in China, five days is a waiting period, three waiting periods are one breath, six waiting periods are one breath and four hours are one year old. Year and year are two different concepts. Year refers to the natural year from the first day of the first month of this year to the first day of the first month of next year. Years old means that the period from a certain solar term this year to the same solar term next year is a year of return. A natural year is 365 days and a tropical year is 365 days, 5 hours, 48 minutes and 46 seconds.

Take spring as an example. In March, everything happened. In the first month, Jian Yin, February, Zhong Chun Jian Mao, March, Jian Chen. Meng Chun's anger is beginning of spring, including "the east wind thaws, the insects start to vibrate, and the fish freeze"; There is a period of rain in Meng Chun, which has three stages: "Rex sacrifices fish, geese come, and plants sprout". At 4: 12, there are 12 gases (24 solar terms), and * * * is seventy-two.