Why do electrical appliances short-circuit in wet weather?

The water in humid air is not pure water (it may contain some ions and inorganic weak acids such as carbonic acid-CO2 in the air is dissolved in water vapor).

Water vapor in the air will liquefy when it meets electrical appliances (the temperature is generally lower than 100 degrees Celsius).

However, water with impurities is conductive. When such liquefied water is in the copper-plated circuit of the printed circuit board of electrical appliances (often bare wires and dense wires), it will produce loops (that is, short circuits) where it should not be.