Abstract
A description is given of a program of observations, carried out over a three-year period, of the sub-millimeter (far-infrared) emission spectrum of the stratosphere. From the discrete emission lines which occur in this spectral region it is possible to measure the total concentration of H2O, and a new technique for doing this is described. The values of stratospheric humidity which have been obtained are presented and discussed as a function of time and of meteorological conditions. An analysis indicates interesting seasonal and longer term trends which should be investigated further.
