Inadvertent Weather Modification by Chicago-Northern Indiana Pollution Sources Observed by ERTS-1

Abstract

NASA's Earth Resources Technology Satellite (ERTS) now provides extremely high resolution (50?200 m) multi-spectral images of any given portion of the earth (between 81° north and south latitude) every 18 days. These are the best unmanned satellite data to date for the detailed study of mesoscale cloud patterns. An ERTS view of the southern basin of Lake Michigan at 1000 CST, 24 November 1972 reveals what certainly appears to be an example of inadvertent weather modification. Cold southwesterly air flow is producing the usual cumulus cloud activity over the relatively warm lake. What is unusual, however, is that the easily visible smoke plumes from a number of major industrial complexes in the Chicago-Gary, Ind., area appear to be markedly affecting the cumulus patterns. Cloud streets developing over Lake Michigan are observed to undergo enhancement when aligned with the industrial plumes. Specifically, the cumulus elements of the cloud streets become larger and brighter (and presumably thicker) than those forming in ?unpolluted? air.