Has the War Affected the Weather?

It is a commonplace of conversation that for some months past the weather conditions have been abnormal, particularly in the matter of rainfall, in the battle zones and elsewhere. Detailed data from regions close to the firing lines are not available; and we have only general statements of inclemency insofar as they affect military operations. But in districts not far away—the British Isles, for instance—the records of excessive raininess during the winter of 1914–15 and at subsequent times have not escaped comment; and others besides meteorologists are discussing the possibility of a connection between the heavy cannonading and the rainfall. The professional meteorologist is called upon to answer whether there is any rational explanation of what appears to be a marked departure from the usual sequence of weather conditions. Is it possible that the tremendous expenditure of ammunition—an expenditure which the layman may well regard as an experiment in concussion sufficiently vast to be decisive—has facilitated condensation and its later stage, precipitation? In concise terms, has the bombarding not only caused clouds but forced the clouds to send down rain? …

Sometimes Nature conducts a rain-making experiment in very dramatic fashion, as when a volcano blows its head off. Thus, when Mont Pelée, Krakatoa, Mount Asama, Katmai, and even little Lassen were in eruption, there were produced the heavy rolling clouds, the lightning, the wind-rush, and the downpour. And not only is there direct rain-making close to the volcano: indirectly and at a distance eruptions cause rain, since the gases and fine ash or dust are carried far and wide by the winds, and … increase the rainfall in countries far removed … Someone will say, do not these facts prove that the claims of “rain-makers” regarding explosions and rains are correct? The answer is, not quite. The explosive output and the atmospheric disturbance in the two cases are not comparable. For example, during one of the recent eruptions of Mount Asama, pressure disturbances were recorded on all the barographs in Japan; but the daily noon gun fired close to the observatory in Tokyo never affects the instruments …

A word or two is in order regarding the claims of those who insist that explosions, particularly gunfire, are accompanied by or cause rain. Edward Powers published a book in 1890 proving to his own satisfaction that the great battles of the Civil War were followed by heavy rain. A wider study of the facts does not bear out the statement. This volume, War and the Weather, led to an appropriation by Congress of the sum of $10,000 for experiments in producing rain by the use of high explosives. The writer witnessed some of these experiments, made under favorable conditions. There was no evidence of a causal relation between the detonations of the dynamite and the showers …

If the war is not the cause of the abnormal weather, what is? We do not know …

Excessive rains have occurred in previous years when there were no wars; and in all probability will occur again, regardless of the prevalence of gunfire.