How is dew formed?

After the plants began to have dew and entered the Bailu solar term, the summer monsoon was gradually replaced by the winter monsoon, and the cold air turned to attack, and the warm air gradually retreated. How did the dew form? I have sorted out the reasons for the formation of dew here for your reference. I hope you will gain something in the reading process!

Reasons for the formation of dew

On a clear and cloudless night with a breezy breeze, flowers, stones and other objects on the ground dissipate heat faster than air, and the temperature is lower than air. When hot air touches these objects with lower temperature, it will saturate and condense into small water droplets and stay on these objects, which is what we see as dew.

Dew is very beneficial to crop growth. In hot summer, during the day, the crops will grow. At night, due to the supply of dew, the crops are revived. In addition, it is beneficial for the crops in the grange to transform and transport the accumulated organic matter.

Dew can only be formed when the atmosphere is stable, the wind is light, the sky is clear and partly cloudy, and the ground heat is lost quickly. If there are clouds in the sky at night, the ground is like a quilt. After the heat hits the clouds, part of it turns back to the ground, and the other part is absorbed by the clouds. This part of the heat absorbed by the clouds will slowly radiate to the ground later, making it difficult for the ground temperature to drop and dew to appear. If the wind is strong at night, the wind makes the upper and lower air communicate, increases the temperature of the air near the ground, and makes the water vapor diffuse, so it is difficult to form dew.

In the early morning of warm season, dew, which people often see on grass, leaves and crops on the roadside, does not fall from the sky. The reason and process of dew formation are the same as frost, except that the temperature is ? Just above C. At ? Above c, the temperature at which the air is saturated with water vapor due to cooling is called "dew point temperature". In warm seasons, when the ground objects are cooled by intense radiation at night, the temperature of the air in contact with the surface of the objects drops, and after it drops to the "dew point", excess water vapor is precipitated. Because the temperature is at this time? Above c, these excess water vapor condenses into water droplets and adheres to ground objects, which is dew.

dew, like frost, mostly appears on sunny nights with no wind or breeze. At the same time, objects that are prone to dew formation are often objects with relatively large surface area, rough surface and poor thermal conductivity. Sometimes, dew forms in the first half of the night, and the temperature continues to decrease in the second half of the night, so that the dew on the object freezes. This is called frozen dew. Some people classify it as frost, but its formation process is different from frost. Dew usually forms at night. After sunrise, the temperature rises and the dew evaporates and disappears. In the growing season of crops, dew often appears. It is beneficial to agricultural production. In the summer in northern China, evaporation is very fast. When there is a lack of rain and drought, the leaves of crops are sometimes dried by the sun during the day, but when there is dew at night, the leaves are restored to their original state. People often call "rain and dew", which is the reason. The origin of the millennium solar term

The millennium is one of the twenty-four solar terms of the lunar calendar, and it is called the millennium solar term when the sun reaches 165 degrees of the Yellow Meridian. The Millennium is the third solar term in autumn, indicating the end of Meng Qiu and the beginning of Mid Autumn. Dew is water droplets condensed by water vapor on the ground or near-earth objects due to the decrease of temperature. Therefore, the Millennium actually indicates that the weather has turned cold. At this time, people will obviously feel that the hot summer has passed and the cool autumn has arrived. The temperature difference between day and night can reach more than ten degrees. Yang qi reaches its peak in the summer solstice, and the extremes must be reversed, and Yin qi also rises at this time. When it comes to the White Dew, the yin is gradually aggravated, and the dew in the morning is gradually thickened and condensed into a layer of white water drops, so it is called the White Dew. As the saying goes:? 18 pots of summer heat, don't show yourself in the Millennium. ? These two sentences mean that it is still hot in the summer, and you must take a bath with a basin of water every day. After eighteen days, when you get to the Millennium, don't be shirtless and naked to avoid catching cold. There is another saying:? The white dew is fascinating, and the autumn equinox rice is beautiful. ? This means that if there is dew before and after the white dew, the late rice will have a good harvest.

　? Bailu? It is a festival that reflects the temperature changes in nature. Lou is? Bailu? A unique natural phenomenon after solar terms. The weather at this time, as the Book of Rites says:? Cool breeze, white dew, chilling. ? According to twenty-four solar term, right? Bailu? The interpretation of water and soil moisture condenses into dew, autumn belongs to gold, golden white, white dew color, and gas begins to be cold? . The ancients also said in Xiao Wei Jing:? The fifteenth day after the summer heat is the Millennium? , Yin qi gradually heavy, dew condensation and white. ? In fact, meteorology shows that: at this point of the solar term, the weather is getting cooler and the sun is still hot in the daytime. However, as soon as the sun returns to the mountains, the temperature drops quickly. At night, the water vapor in the air condenses into tiny water droplets, which are very densely attached to the green stems, leaves or petals of flowers and trees, showing white color. Especially after being irradiated by the morning sun light, it looks more crystal clear and flawless, which is really attractive. Bailu? Good name.