When does dew usually form? Like a clear, calm morning? Wait a minute.

Dew is a liquefaction phenomenon in which water vapor in the air liquefies on objects covered on the ground in the form of water droplets. When the temperature drops at night, the closer to the ground, the faster the temperature drops, forming a temperature distribution opposite to that during the day. When the ground temperature is cooled to saturation, dew can be observed on the ground objects. If the temperature continues to drop below 0℃, dew freezes into ice beads, which is called frozen dew. After sunrise, the distribution of temperature and humidity on the ground becomes completely opposite to that at night, and the warming of air near the ground also makes the water vapor content in the air layer unsaturated. All kinds of conditions will be conducive to the evaporation of ground water, and dew will gradually disappear.

Therefore, the formation of condensation is caused by the large temperature difference between the air. Not only the ground in the morning, but also the water droplets condensed on the indoor glass in winter and the outer wall of the frozen beverage bottle in summer are all in the form of dew.