Air flow in throttle valve

The origin of the twenty-four solar terms originated in the Yellow River Basin. As early as the Spring and Autumn Period, four solar terms were set, namely, mid-spring, mid-summer, mid-autumn and mid-winter. After continuous improvement and perfection, by the Qin and Han Dynasties, the 24 solar terms had been completely established. In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms. The time when the sun runs along the longitude of the Yellow River from zero 15 degrees is called "a solar term". It runs 360 degrees every year, and * * * experiences 24 solar terms, twice a month. Among them, the first solar term of each month is "solar term", that is, beginning of spring, Jingzhe, Qingming, Changxia, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, Heavy Snow, Xiaohan, etc. 12 solar terms; The second solar term of each month is "Zhongqi", that is, there are 12 solar terms such as rain, vernal equinox, Grain Rain, Xiaoman, summer solstice, great heat, intense heat, autumnal equinox, first frost, light snow, winter solstice and great cold. "Solar term" and "neutral qi" appear alternately, each lasting 15 days. Now people have called "solar terms" and "neutral gas" solar terms. Twenty-four solar terms reflect the apparent movement of the sun in one year, so the dates of solar terms are basically fixed in the current Gregorian calendar, with the first half of the year being 6 days and 2 1, and the second half being 8 days and 23 days, with a difference of 1 ~ 2 days. In order to facilitate memory, people have arranged 24 solar terms: spring rain, song Jing, spring and clear valley days, summer full and summer hot, autumn cold and frost falling, and winter snow falling. The earth goes around the sun, and it takes a year to complete a circle. A year is divided into December, and the 24 solar terms are closely linked. According to the Gregorian calendar, these two gases will not change every month. The first half of the year is Saturday and Monday, and the second half is every eight days and every Wednesday. These are festivals, and the difference is only one or two days. In the twenty-fourth section, I remember the following formulas in my mind: a slight cold followed by a severe cold in January, and a rainy day in beginning of spring in February; The vernal equinox is in March and Qingming Grain Rain is in April. Long summer and full summer in May, full summer solstice in June; July is hot and slightly hot, and August is long summer, beginning of autumn; In September, the Millennium meets the autumnal equinox, and the first frost and cold dew are all in October; There is a light snow in 1 1 month in beginning of winter, and a heavy snow in winter solstice to welcome the New Year. Grasp the season and busy production, sow and harvest in time to ensure a bumper harvest. With the spread of China calendar, the 24 solar terms have spread to many parts of the world. Beginning of spring: beginning of spring is standing, and beginning of spring is beginning of spring. Rain: It began to rain and gradually increased. Sting: Sting means hiding. Sting refers to the sudden movement of spring thunder, which awakens the hibernating animals in the soil. Equinox: Equinox means equal share. The vernal equinox means that day and night are equally divided. Qingming: sunny and lush. Grain Rain: Rain makes a hundred valleys. With sufficient and timely rainfall, cereal crops can thrive. Long summer: the beginning of summer. Xiaoman: Summer crops such as wheat are full of seeds. Miscanthus species: Miscanthus crops such as wheat are mature. Summer solstice: The hot summer is coming. Summer heat: Summer heat means heat. Slight summer heat refers to when the climate begins to get hot. Big institutions: the hottest time of the year. Beginning of autumn: The beginning of autumn. Summer heat: place means stop and hide. Summer is the end of hot summer. White dew: The weather turns cold and the dew condenses into white. Autumnal equinox: divided equally between day and night. Cold dew: Dew is cold and will freeze. First frost: it's getting colder and colder, frosty. Beginning of winter: The beginning of winter. Xiaoxue: It's starting to snow. Heavy snow: the snowfall is increasing, and there may be snow on the ground. Solstice of winter: the cold winter is coming. Slight cold: The climate began to get cold. Great cold: the coldest time of the year.