What is the specific time calculation method in the 24 solar terms?

What you think is right. Twenty-four solar terms are the most solar terms in the world. It is formulated directly according to the laws of the movement of the sun (actually, the revolution of the earth). Intuitively, each solar term corresponds to the height of the fixed sun. Twenty-four solar terms are based on "dichotomy". Insert an average of 20 solar terms. From the perspective of modern science, each solar term corresponds to a precise point on the earth's orbit around the sun. So when you see beginning of spring in one place, the height of the sun is the same at noon every year; Sunrise and sunset are the same time.

As for what you said, there is often a day difference between solar terms and calendars. This is because the official calendars published by China are based on the data measured by the National Astronomical Observatory. Some calendars in Hongkong and Taiwan Province are based on the "perpetual calendar" revised by the Ming Dynasty. For example, the severe cold solar terms of 20 12 were calculated by the Observatory at 0: 10/0 on1day. Actually, it's only 10 minutes from the 20th. Isn't it strange that the calendars compiled by the ancients have this error? However, the ancients in our country are quite powerful. There won't be a big error. Check it. Generally, when there are differences in various calendars, the exact time of this solar term is either 23: 50 or 0: 00.