Stability of the atmosphere at different levels is one important factor affecting the behavior of forest fires, but the measurement of stability and other atmospheric phenomena is complex and difficult. The acoustic echo sounder shows promise for measuring these parameters and for monitoring the pattern of air flow superimposed on the ambient atmosphere by an intense heat source, such as a forest fire. It is particularly well suited for monitoring the depth of stable inversion layers and for providing a qualitative indication of the degree of stabiliity in the lower atmosphere. The addition of a Doppler capability to acoustic systems has also made it possible to sense remotely a vertical profile of the total wind vector to heights of 500 m.© Society of American Foresters, Bethesda, MD. Abstract reproduced by permission.