The equinox sun is almost direct to the Earth’s equator, and the globe is almost equal in length and length. After the vernal equinox, the sun's direct point began to enter the northern hemisphere, and the northern hemisphere began to grow shorter and shorter. The vernal equinox is an important solar term. It not only has astronomical significance: the northern and southern hemispheres are divided equally between the day and night. In the climate, there are also obvious features. In addition to the Qinghai-Tibet Plateau, northeast, northwest, and northern northern China, the spring equinox has entered a bright spring. In the spring, on the vast land, there will be green willows, long grasshoppers, wheat joints and rapeseed flowers.
During the spring equinox, the large troughs in East Asia weakened significantly, and the activity of the westerly ridges increased significantly. From Mongolia to the northeast, there were often low-pressure activities and cyclones. Low-pressure movements led the cold air southwards, and the northern regions had much wind and sand blowing. When the long wave trough is moved eastward, continuous cold weather and cold weather will occur due to the influence of cold and warm air masses.
In the equinox season, except for the alpine mountain areas in the winter and the areas north of latitude 45° north of the year, the average daily temperature in China has steadily risen above 0°C. At this time, the cold has passed and the temperature has risen rapidly. Especially in North China and the Huanghuai Plain, the average daily temperature has risen by more than 10°C with rainy riverside regions and has entered the bright spring. On the vast land, the shore will be green, the grass will fly long, the wheat will be jointed, the rape will be fragrant, the pink and white will be spring yellow, and the South China region will be a scene of late spring. According to the law of the climate, the precipitation in the south of the Yangtze River rapidly increased and entered the spring “Peach Blossom” period; precipitation is still rare in the northeast, north, and northwest regions of the “spring rain is as oily” and the threat of spring drought is agricultural production. The main problem.