ON METEORS AND RAINFALL

Abstract

The correlations of heavy rainfall and of noctilucent clouds with meteor streams are examined with regard to the known facts of meteor astronomy. Photographic and radar observations show that the general influx of sporadic meteors is not greatly enhanced by the occurrence of a meteor stream, and it is unlikely that meteors within the present limits of observation could produce a change in the number of freezing nuclei sufficient to cause heavy rainfall. Comprehensive measurements of daylight meteor streams are cited which show no detailed correlation with the observations of noctilucent clouds?the meteoric debris suspended in the upper atmosphere. This again indicates that the debris contributed by observed meteor streams is insignificant. The role of micrometeorites that enter the atmosphere without producing detectable light or ionization is considered. It is possible that a profusion of micrometeorites in a stream could affect the rainfall. But in space these particles must be removed from the stream before they are dispersed into sporadic orbits; otherwise the streams would not be so conspicuous against the sporadic background. A mechanism for removal is suggested which depends on the gradual disintegration of micrometeorites under the influence of corpuscular radiation from the sun.