Traditional Culture Encyclopedia - Weather forecast - How to divide1February into four seasons, and the basis for division?
How to divide1February into four seasons, and the basis for division?
① Ancient times
In ancient China, beginning of spring, Changxia, beginning of autumn and beginning of winter were four seasons.
On the calendar published in China, next to the date of a year, there is also a lunar calendar, also called the summer calendar, which is what we usually call the "lunar calendar". According to China folk customs, the lunar month is divided into four seasons: January to March is spring, April to June is summer, July to September is autumn, and October to December is winter. Children are looking forward to "Year", which refers to the first day of the first lunar month; This day is not only the first day of the year, but also the beginning of spring in the division of lunar seasons, so it is called the Spring Festival.
② astronomical calendar
Astronomically, the spring equinox, summer solstice, autumn equinox and winter solstice are four seasons.
③ Meteorology
Meteorologically, March to May is usually spring, June to August is summer, September to165438+1October is autumn, and June to February is winter.
If you think about it carefully, you will find that there is a problem in the above four seasons division methods: no matter where you are, you will enter the same season on the same day, which is very different from the actual climate conditions in various regions. For example, according to the above standards, March should be spring. At this time, the swallow grass in Jiangnan is long, pink and green, and the spring is really strong; Heilongjiang province is still freezing cold and snowy; Moreover, it is already a hot summer day in Hainan Island, so you can wear light clothes.
Seasonal changes are closely related to people's lives and industrial and agricultural production. Can we formulate a standard for dividing the four seasons in line with the changes of natural scenery?
In order to reflect the phenological phenomenon of seasonal changes in an area as truly as possible, the meteorological department divides the four seasons with the five-day average temperature (referred to as average temperature) as the index:
The first day when the daily average temperature steadily exceeds 10℃ for five consecutive days is called beginning of spring Day.
The first day when the average daily temperature has steadily exceeded 22℃ for five consecutive days is called Lixian.
The first day when the daily average temperature is steadily lower than 22℃ for five consecutive days is called beginning of autumn Day.
The first day when the daily average temperature is steadily lower than 10℃ for five consecutive days is called the winter day.
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