Dew Point
¥DP-temperature to which air must be cooled at constant pressure to become saturated (at which point dew forms).
¥Higher DP Þ Higher water vapor content.
¥DP is a good indicator of the actual water vapor content since air pressures vary very little along the earthÕs surface.
¥DP is plotted on surface weather maps.  
¥DP depression (Temp-DP) is plotted aloft.