Twenty-four solar terms: vernal equinox

March 2 1 day is the vernal equinox among the 24 solar terms, and the vernal equinox solar terms begin when the sun runs to 0 degrees (vernal equinox). A day is half of spring, so it is called vernal equinox. On the vernal equinox, the sun shines directly at the equator, and day and night are almost equal. Then the direct sunlight position gradually moved northward, and the days were long and the nights were short.

During the spring equinox and solar terms, the East Asian trough is obviously weakened, and the trough ridge activity in the westerly belt is obviously enhanced. From Mongolia to the northeast, there are often low-pressure activities and cyclone development. Low-pressure movement causes cold air to go south, and it is windy and windy in the north. When the long wave trough moves eastward, there will be continuous rainy and cold weather due to the intersection of cold and warm air masses.

Proverbs about vernal equinox and solar terms can be divided into four categories: one describes the length of day and night, such as "vernal equinox and autumnal equinox, which divide day and night equally" and "eating vernal equinox makes the day longer"; One is to predict the weather in the later period according to the sunny rain at the vernal equinox, such as "rain at the vernal equinox and flood at the autumnal equinox"; One is to predict the weather in the later period according to the cold and warm weather, such as "spring equinox is not cold, sunny and cold", "spring equinox is not warm, autumn equinox is not cold"; Another is to predict the weather in the later period according to the wind, such as "the west wind is rainy at the vernal equinox", "If the vernal equinox is warm, it will be sunny after the water in May" and so on.

The overwintering crops of vernal equinox and solar terms have entered the spring growth stage, so it is necessary to strengthen field management. Cotton nutrition bowl sowing should choose cold tail and warm head, and proceed at the right time.