The dog days are composed of three independent dog days: the first, the middle and the last. The first and last days are 10 days, and the middle days are divided into 10 days and 20 days, and both the first and last days have a fixed time statement.
Toufu is a time node of "Three Geng Toufu in Summer Solstice", which means starting from the Summer Solstice and counting to the third Geng Day, which is the time of lodging.
Basic introduction
The dog days appear between the light summer heat and the summer heat (from mid-July to mid-August in Gregorian calendar), and the dog days are divided into initial, middle and last days. The dog days are characterized by high temperature, low air pressure, high humidity and low wind speed. "Fu" means that Yin qi is forced to hide underground by Yang qi, and the date of three volts is determined by the coordination of the solar term date of the dry branch calendar and the date of the dry branch calendar.
Because the interval between each Geng day is 10 days, the stipulated time for initial and final lodging is 10 days. And because the third Geng day (first fall) after the summer solstice solar terms appears sooner or later, the number of days in the fall is long and short.