C Floor

Abstract: To an observer who has a clear and unobstructed view of the distant horizon the setting of the sun is one of the most fascinating phenomena that can be seen in nature. The shapes and the colours of the disc of the setting sun are both beautiful and surprising, and they can be explained in terms of refraction. scattering and dispersion of light in the atmosphere. Teachers may therefore be able to explain and illustrate these topics of physics with the help of sunset phenomena. Linked classroom experiments on atmospheric refraction and scattering have been described elsewhere (e.g. Trowbridge 1973. Kruglak 1973, Johnston 1977). Although my comments in this article relate to the setting sun, they apply equally well to the rising sun. I shall deal with normal sunset phenomena, sunsets over warm land or water and the characteristics of sunsets that occur when there is a layer in the