What does White Dew mean?

White Dew is the 15th solar term in the 24 solar terms of the lunar calendar. White Dew is when the sun reaches 165th degrees of longitude. When the weather gets cooler, you will find many dewdrops on the ground and leaves in the early morning, which is named because water vapor condenses on it at night. The ancients to 04:00 with five elements, autumn is golden, golden white, so white to describe Qiu Lu, into the "White Dew", the evening will feel a trace of coolness.

What does White Dew mean?

White Dew is the third solar term in autumn, indicating the end of Mengqiu season and the beginning of mid-autumn season. Dew is a drop of water formed by the condensation of water vapor on the ground or near-earth objects due to a drop in temperature. Therefore, White Dew actually indicates that the weather has turned cooler. At this time, people will clearly feel that the hot summer has passed, and the cool autumn has come. The temperature difference between day and night can reach more than ten degrees. Yang Qi reached its peak when the Summer Solstice reached its peak, things will turn back at the extreme, and Yin Qi also rises at this time. To White Dew, Yin qi gradually increased, and the early morning dew became thicker and thicker, condensing into a layer of white water droplets, so it was called White Dew.

White Dew and Agriculture

The cold air in White Dew is becoming more and more active in season, and the low temperature weather often occurs in autumn, which affects the heading and flowering of late rice, so it is necessary to prevent low temperature chilling injury and diseases and insect pests. When cold air invades, irrigation can be used to keep warm. Irrigation before low temperature is more than two inches, and the temperature can be increased by 1 / 2 ℃. When the low temperature comes, shallow water can be irrigated day and night in sunny days, and thick water should be irrigated in cloudy and rainy days. Generally, the weather should be dry and wet, mainly wet. This solar term, the heat is gradually fading, the autumn is crisp, the jade dew is cool, and the cinnamon is fragrant, which is the golden tourist season. "White Dew" is at the turning point of summer and autumn, and the temperature varies greatly during the day. The old, weak and sick should pay more attention to adding or decreasing their clothes at the right time to prevent catching cold.

The weather change of White Dew

After entering White Dew's solar terms, the summer monsoon was gradually replaced by the winter monsoon, the cold air turned to attack, and the warm air gradually shunned. Cold air moving southward in batches often brings a certain range of cooling. People like to use the proverb "White Dew autumn breeze night, cool night" to describe the accelerated decline in temperature.

The precipitation in northern China is obviously reduced, the autumn is crisp, and it is relatively dry. In the middle and lower reaches of the Yangtze River during this period, the first autumn rain can often alleviate the previous water shortage, but if the cold air meets the typhoon, or the cold and warm air is neck and neck, when the two sides are in a difficult situation, the formation of heavy rain or low temperature continuous rain is disadvantageous to the growth of autumn crops. Continuous rainy weather often occurs in the eastern part of southwest China, South China and West China.

Torrential rains caused by tropical weather systems (typhoons) may also occur along the southeast coast, especially along the coast of South China. In addition, there may be autumn drought, forest fire insurance, first frost and other weather in some areas at this time. If the summer drought in the middle and lower reaches of the Yangtze River and the summer drought in West and South China are not moistened by autumn rain, it may lead to continuous drought in summer and autumn.

Some parts of northern China, such as Shaanxi, Shanxi, Gansu and North China in the northwest, have less precipitation in autumn. if there is a serious autumn drought, it will not only affect the harvest of autumn crops, but also delay the sowing and emergence of autumn crops, affecting the harvest of next year. In addition, with the autumn drought, especially in the mountain forest areas, the air is dry and the wind increases, and the forest fire insurance begins to enter the autumn high incidence period.