The mechanism of formation of desert mirages

摘要

The mirage is a unique optical phenomenon in the desert. This paper investigates the mechanism by which they form. Optical experiments in the Gobi show that the refractive index decreases about 20 to 40 cm above the ground causing a total reflection of ground surface light. Thus, ground light cannot get through and a 'water surface' mirage is formed-objects that are higher than the mirage will form an inverted image by reflection. Temperature and humidity monitoring prove that inversion of the refractive index occurs under the mirage. Mirage formation is mainly caused by temperature inversion in the 20 to 40 cm layer of the atmosphere, and phreatic water evaporation is the main reason for the formation of this temperature-inverted layer. The desert mirage is a phenomenon involving both total reflection and mirror reflection.