Question

Dew point temperature is the temperature at which condensation begins when

Answer 1

Dew point temperature is the temperature at which condensation begins when the air is cooled at constant pressure

If a sample of unsaturated air, containing superheated water vapour, is cooled at constant pressure , the partial pressure (Pv) of each constituent remains constant until the water vapour reaches the saturated state. At this point, the first drop of dew will be formed and hence the temperature at this point is called dew point temperature.