30-year rhyme weather

In ancient times, on the fifteenth day of the first month, people generally had the custom of watching lanterns in the garden, so there was a saying that it snowed on the fifteenth day of the first month.

The reason is precisely because the weather has a corresponding rhythm relationship. Rhythm means that after a certain weather appears, the corresponding weather will appear in the next few days.

The duration of this rhythm varies from 30 days, 60 days, 90 days, 120 days, 150 days, 180 days and 240 days. According to the lunar calendar, "Yun Zheyue on the 15th of August, snow lanterns on the 15th of the first month" is exactly the rhythm of 150 days. According to historical data, whenever the Mid-Autumn Festival is cloudy, cloudy or rainy, it will be cloudy or snowy on the fifteenth day of the first month of next year.