GREEN THUNDERSTORMS OBSERVED

Green thunderstorms have been observed from time to time in associatio n with deep convection or severe weather events. Often the green color ation has been attributed to hail or to reflections of light from gree n foliage on the ground. Some skeptics who have not personally observe d a green thunderstorm do not believe that green thunderstorms exist. They suggest that the green storms may be fabrications by excited obse rvers. The authors have demonstrated the existence of green thundersto rms objectively using a spectrophotometer. During the spring and summe r of 1995 the authors observed numerous storms and recorded hundreds o f spectra of the light emanating from these storms. It was found that the subjective judgment of colors can vary somewhat between observers, but the variation is usually in the shade of green. The authors recor ded spectra of green and nongreen thunderstorms and recorded spectral measurements as a storm changed its appearance from dark blue to a blu ish green. The change in color is gradual when observed from a station ary position. Also, as the light from a storm becomes greener, the lum inance decreases. The authors also observed and recorded the spectrum of a thunderstorm during a period of several hours as they flew in an aircraft close to a supercell that appeared somewhat green. The author s' observations refute the ground reflection hypothesis and raise ques tions about explanations that require the presence of hail.