It rained today. In which year is the rainy day 30 days? In which years are the dog days 40 days?

The lodging time of each year starts from the third Geng day of the summer solstice and is repeated every 65,438+00 days. If there are four Geng days between the summer solstice and the beginning of autumn, the intermediate lodging time is 65,438+00 days; If there are five Geng days, the middle lodging is 20 days, and the annual Geng day is uncertain, so the dog days are sometimes 30 days and sometimes 40 days. As for which years are 30 days and which years are 40 days, it depends on the specific entry date of each year, which can be found online.