According to the International Research Institute for Climate and Society at Columbia University, dew point is defined as "...the temperature to which the air must be cooled at constant pressure in order for it to become saturated, i.e., the relative humidity becomes 100 percent." What that means, in simple terms, is that the dew point is the temperature at which the moisture in the air becomes liquid water. It is a complicated calculation to determine the dew point, but according to Mark G. Lawerence in a 2005 paper published through the American Meteorological Society, there is a relatively simple approximation that can be used.