Abstract/Young ATM-9714357 The term green flash refers to a class of poorly understood atmospheric refraction phenomena that have been observed by reliable observers for many years on occasion when the sun is near the horizon. It is often described as a brief flash of green light at the upper edge of the setting sun, but the term is misleading, for several reasons. First, there are several different observable phenomena that have been called green flashes in the past. Second, the colors can range from yellow to violet. Third, there is no flash literally. One can speculate that the term flash has been applied because of the brevity, not the intensity, of the phenomenon. There is a simple, but mostly inadequate, model that attempts to explain the phenomenon in one of its forms. There are neither quantitative theories nor qualitative explanations for any of the other observed forms. The objectives of this research are 1) to determine how many different atmospheric refraction phenomena can be grouped under the heading of the phenomena know popularly as green flashes , 2) to assess the relative importance of molecular absorption as a causative factor, and 3) to develop a model to predict the observed colors and to compare the predictions with existing observations. The achievement of these objectives will not only move the phenomena from the poorly-understoood category to the at-least-basically-understood category but also but also provide insights regarding possible techniques that might be developed to determine at least the algebraic sign of the temperature structure of the boundary layer passively under certain conditions that might eventually be of practical use.
