The morphology of tropospheric rivers has been examined for the period June 1991--May 1992 from atmospheric specific humidity and wind velocity data. Vertically integrated water vapor flux vectors are subjected to harmonic analysis and the high frequency components (periods less than 3 days) show large amplitude values in the North Atlantic, North Pacific, South Atlantic, South Indian Ocean and South Pacific plus small amplitude occurrences in the Red Sea-Arabian Sea region in the December--February season. In June--August the latter is replaced with a large amplitude monsoon-related region over South-East Asia. Maximum intensities increase slightly in altitude with latitude. The correspondence between rivers, frontal boundaries and storm tracks is noted. Sometimes rivers originating over the North Pacific cross North America and reach Greenland while at other times they pass polewards over the North Atlantic, raising the possibility that water vapor involved in ice core formation may have evaporated from surface water bodies with different temperature and salinity characteristics. Changes in oxygen isotope variations at a point may therefore reflect changes in the dynamics of tropospheric rivers in addition to local temperature changes. ¿ American Geophysical Union 1994