1, when there is too much water vapor in the air, it will condense to form water mist, that is, gaseous substances will become liquid substances for liquefaction.

2. When a substance changes from solid to liquid, this phenomenon is called melting, which requires heat absorption, such as ice absorbing heat and melting into water. On the contrary, when a substance changes from a liquid state to a solid state, this phenomenon is called solidification, and solidification requires heat release, for example, water is exothermic and solidified into ice, and ice changes from a liquid state to a gas state. This phenomenon is called vaporization, and there are two ways: vaporization and boiling. Evaporation occurs on the surface of liquid, which can be carried out at any temperature and has a slow speed. Boiling occurs on the surface and inside of the liquid and must reach the boiling point, which is intense. Vaporization requires heat absorption, and liquids have boiling points. When the temperature reaches the boiling point, the temperature will not rise again, but it is still absorbing heat. When a substance changes from a gaseous state to a liquid state, this phenomenon is called liquefaction, which gives off heat. For example, water vapor is liquefied into water and water is evaporated into water vapor. The phenomenon that a substance directly changes from a solid state to a gas state is called sublimation, and then the substance directly changes from a gas state to a solid state. This is called sublimation, which absorbs heat and releases heat.