What are the dog days? Why only in the almanac?

Initial, intermediate and final accommodation. The first and last days of each year are 10 days, and the middle days are 10 days or 20 days. The specific date of the dog days is determined by the solar term date and the dry branch date. Geng, ranked seventh in the heavenly dryness, belongs to gold in the collocation with the five elements, and gold is afraid of fire, which decreases day by day in the weather of several volts, so the ancients counted Geng Day as "volt". According to the traditional calculation method in China, the third and fourth Geng days from summer to the future are the start dates of the first (recumbent) and the second (recumbent) respectively, and the first Geng day after beginning of autumn is the first day of the last (recumbent). The length of the dog days is not exactly the same every year. If the middle section ends after beginning of autumn, it is 30 days. If the middle section ends before beginning of autumn, it will be 40 days (20 days in the middle section).

Climatic characteristics in dog days

High temperature, low pressure, high humidity and low wind speed are the hottest seasons of the year. This is because, in summer, the day is longer than the night, the day is longer and the sunshine time is longer. The heat absorbed by the surface is far greater than the expenditure, which makes the heat accumulated on the surface increase day by day and the temperature continues to rise. In midsummer, that is, in dog days, the accumulation of surface heat reaches its peak. In summer, there is much rain and high air humidity, and the heat capacity of water is much larger than that of dry air, which is also one of the important reasons for the sultry weather.

The ancients lived in a bad environment, without air conditioning and electric fans. Imagine, if you practice martial arts under such difficult conditions, will it be a great test of people's willpower? No wonder it says "Summer training is in the dog days".