Equ 2.5 Dry bulb, wet bulb and dew point temperature
Unless otherwise specified, the temperature of an air-water vapour mixture is that temperature which is indicated by an ordinary or dry-bulb thermometer. This dry-bulb temperature is the temperature of both the air and the water vapour in the mixture. The wet-bulb temperature may be determined by submerging a water-covered bulb in the air-water vapour mixture until equilibrium is obtained.
The wet-bulb temperature will be lower than the dry-bulb temperature as long as evaporation continues. If no evaporation is possible, the mixture is saturated and the wet and dry-bulb temperatures for this condition will be identical, the dew point temperature of an air-water vapour mixture is the saturation temperature corresponding to the absolute humidity of the mixture.
The dew point temperature may also be considered as that temperature at which condensation begins when the mixture is gradually cooled.
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