Dew is a bead of water that condenses near the ground at night or in the morning Xiaoice crystals and then melts on an object. ("Hand Shooting World" is Weiming's mobile phone photography works, please pay attention to the headline number and WeChat public number: Weimingfang)
In the early morning, we can often see small shiny water droplets on some grass leaves, which is dew.
In ancient times, people thought that dew was a precious water that fell from other planets, so many folk doctors and alchemists paid attention to collecting dew and using it to cure all diseases and refine "immortality".
On a cloudless, breezy night, due to the flowers, plants, stones and other objects on the ground, heat dissipation is faster than air, and the temperature is lower than air. When the hotter air touches these lower-temperature objects, it saturates and condenses into small droplets of water that remain on these objects, which is the dew we see.
Dew is very beneficial to crop growth. In the hot summer, during the day, the photosynthesis of crops is very strong, and a large amount of water will evaporate and mild wilting occurs.
At night, the crops were brought back to life due to the supply of dew. In addition, crops that favor farms convert and transport accumulated organic matter.
Dew exists all year round, especially in autumn. On a clear and cloudless night, the heat on the ground dissipates quickly and the temperature on the ground drops rapidly.
When the temperature decreases, the ability of the air to contain water vapor decreases, and the water vapor in the lower layer of the atmosphere is attached to the grass, leaves, etc., and condenses into small water droplets, that is, dew.
Dew needs to be formed under the weather conditions of a relatively stable atmosphere, small winds, clear skies and few clouds, and rapid heat dissipation on the ground.
Dew can be used in medicine, can be used to decoct lung insecticides, or the treatment of scabies, insect pestilence powder into external dressing, can enhance the efficacy.