1. When evening or night comes, the ground or ground features will be cooled by radiation, so the air layer near the surface will also be cooled. When the temperature drops below the dew point, that is, the water vapor content in the air is supersaturated, there will be water vapor condensation on the ground or surface of the ground. If the dew point temperature is above 0℃ at this time, tiny water droplets will appear on the ground or ground objects, which is dew.
2. Dew generally refers to dew. Dew (Lu) refers to liquid water formed by condensation of water vapor in the air on ground objects.