04 January 1991
Vol 251, Issue 4989

About The Cover

Containment of elevated concentrations of the ClO free radical (shown in green) in the stratosphere above the Antarctic continent occurs within the wind jet generated by cooling during the austral winter night. Isolation of the vortex, that region poleward of the wind field maximum, is an important element in the case linking chlorofluorocarbon release to ozone destruction over Antarctica. See page 39. [Artwork by Joseph Spatola]