Radiosonde humidity distributions over the United States, Canada, and Europe are discussed. Striking dry-end and wet-end differences are caused by the lack of international standards in the transformation of relative humidity observations to dewpoint depression and in differing ways of calibrating data taken from the same type of instrument. Differences in sondes used in these regions are also discussed and an example of a dual ascent is shown. Some implications for remote sensing and weather prediction are highlighted.
*Atmospheric Environment Service, Dorval, Quebec, Canada.
+Atmospheric Environment Service, Downsview, Ontario, Canada.