Evaluation of a one-dimensional cloud model for yellow and green thunderstorms.

Many observers have reported observations of green light emanating from severe thunderstorms in the midwestern United States. Spectral measurements have demonstrated that the dominant wavelength of the light is in the green portion of the visible spectrum and that this is not just a subjective impression. According to the theory proposed by Bohren and Fraser [Bull. Am. Meteorol. Soc. 74, 2185 (1993)], two effects combine to produce green light from thunderstorms. First, incident solar radiation is reddened by selective scattering by air molecules and particles in the atmosphere before it enters the cloud. Second, the radiation that passes through an optically thick cloud is attenuated in the longer wavelengths because of selective absorption by liquid water. Model calculations indicate that realizable combinations of mean drop diameters, mean liquid-water contents, and cloud thicknesses can satisfy the conditions required for shifting the dominant wavelength of the incident solar radiation to green.