Ente Nazionale per l'Energia Elettrica (E.N.E.L.), like other large electric power agencies all over the world, is facing the problem of smoke dispersion from the stacks of large power stations. We are carrying out a research programme on some aspects of this problem. Because of topographical and orographical features of our country, the usual formulae for effective stack height and gas dispersion have to be used very carefully and a deep understanding of the local behaviour of the low atmosphere is always necessary. For this purpose, we tried pilot balloon sounding at three power stations, on the Po valley, on the shore of the Ligurian sea and in a mountain valley in southern Italy. We obtained useful information about the motion and the layering of the low atmosphere between 75 and 1500 m.