Maximum relative ambient humidity (RH – Relative Humidity)

Permissible relative ambient humidity (RH – Relative Humidity) is a value expressed as a percentage (0–100%); according to the definition it is the amount of water vapour present in a specific volume expressed as a percentage of the amount needed for saturation at the same temperature. At different air temperatures, the same relative humidity will mean two different amounts of water vapour in the air.

In simple terms, the closer the value to zero, the dryer the air. And vice versa - the closer the value to 100%, the more the air is saturated with water vapour. At 100% relative humidity, cooling the air will result in water vapour condensation, which may affect operation of electric devices.