Precipitable Water Vapor in Atmospheres Characterized by Temperature Inversions

The total atmospheric precipitable water W has been measured with an infrared hygrometer for different atmospheric conditions and various seasons. Related to the simultaneous dew-point temperature Td at the surface, these data indicate that correct estimates of W can be given by the relationship lnW = a + b Td [first proposed by Reitan (1963)] only if properly chosen values for the intercept parameter a are used corresponding to the various periods of each day. The examination of both spectral hygrometer and radiosonde data taken in atmospheres characterized by marked temperature inversions shows that the parameter a is related closely to the ratio β between the surface absolute humidity and W. On the other hand, this ratio appears to depend substantially on the general form of the vertical moisture profile of the low atmosphere. Thus empirical relationships are proposed which give the possibility of inferring from empirical values of β estimates of the partial precipitable water content within low atmospheric layers and of the absolute humidity at some standard levels, when radiosonde data are not available.