Does dew point temperature remain constant over altitude, pressure, and density? I have to admit that I am having difficulties fully understanding dew point temperature. I understand that dew point temperature is simply the temperature to which a given parcel of air must be cooled under constant pressure, for it to condense/deposit. Simple. However, how does this relate to the actual atmosphere? In this case the International Standard Atmosphere. As altitude increases, temperature, pressure, and density changes. If dew point remains constant, I can understand how clouds form, since temperature decreases the first 11 km (by 0.0065 K/m) which would allow water vapour to condense/deposit. However, is dew point constant over altitude? or does it decrease along with temperature? Then how can clouds form at all?