Model output cloud and vapor mixing ratio field on grid 4 at 2100 UTC on 15 May 1991. Figure (a) shows convective storm development with "actual" land cover derived from USGS data. Figure (b) shows convective storm development treating the land surface as shortgrass steppe. (from Pielke, R. A., T. J. Lee, J. H. Copeland, J. L. Eastman, C. L. Ziegler, and C. A. Finley, 1995. "Use of USGS-provided data to improve weather and climate simulations," Ecological Applications, in press.)