Smoke and Rain

Abstract

IN a paper published in 1929¹ the conclusion was drawn from observations made in two or three different ways that smoke discharged into the atmosphere tends to promote rainfall and to precipitate rain in highly moist air when, without smoke, it would not have fallen. One test was to compute the rainfall on each day of the week, and the result showed that on an average of thirty years, Sundays had rather less rain than weekdays by about 6 per cent, or more correctly, the average of weekdays had an excess over Sundays by this amount. As factories in Hochdale and neighbouring Lancashire towns do not work on Sundays there is then a general absence of smoke in the air, although domestic smoke, which is of less importance, continues. The outpouring of factory smoke on working weekdays was considered to be the cause of the excess of rain on weekdays over Sundays.