The distribution of diabatic heating is diagnosed from ECMWF analyses. In the upper troposphere, there is heating in regions of deep convection particularly in the Western Pacific. However at 70 hPa in the lower stratosphere, heating occurs in the subtropics and in the Eastern Pacific while cooling (or only weak heating) occurs in the Western Pacific. Comparison is made with the distribution of outward longwave radiation and this shows strong similarity to the diabatic heating in the lower stratosphere. This suggests that longwave heating from absorption by ozone of upward radiation in the 9.6 &mgr;m band is important in determining the distribution of heating rates in the tropical lower stratosphere. The distribution of upward longwave radiation is strongly modulated by the distribution of convectively generated high-level cirrus clouds. This produces anticorrelation between heating rates in the tropical troposphere and lower stratosphere. ¿ 2001 American Geophysical Union