Distant Green Thunderstorms—Fraser’s Theory Revisited

Abstract

The theoretical development presented by Fraser can produce a spectrum of light that would be perceived as a faint green. The theory assumed a perfectly black background thunderstorm. Severe thunderstorms are certainly not black when observed from a distance of 30?40 km. Thus it is useful to compare the theory with some observed examples of severe thunderstorms that should have been green by the Fraser theory but were not. Therefore, some elementary modifications of the Fraser model such as using a nonblack background are suggested. The use of a nonblack cloud background tends to shift the resulting dominant wavelengths away from the green portion of the spectrum, suggesting a better match with observations.