There has been increasing interest in studying the rise of hot smoke plumes from large power plants in relation to the dispersion of atmospheric effluents. A number of plume rise formulas derived primarily from data on small stack emissions are in popular use. Application of these formulas to increasingly larger emission sources warrants a closer examination of their conformity with actual experience. The objective of the research reported was to define the plume profile for various combinations of generating unit sizes, stack heights, and meteorological conditions. Three separate simultaneous field measurement techniques were used--ground level photography, ground level modified transit readings, and helicopter observations. Ground photography was the principal source of data. (Author)