TCD MS 10515 folio 53v
[April 28th 1916]
Physical Phenomena
Production of Mirage
As we gaze out over the desert into that elusive sheet of undulating plain which displays before our eyes the affect of a mirage, it is possible to follow in their gradual development the transient phenomena y which it is formed. Firstly it must be remembered that the sand of the desert is hot, extremely hot, so hot that it is burning to the touch on a summer’s day. This burning sand raises the temperature of the layer of air in direct contact with it. (*) Powerful convection currents are developed in this burnt atmosphere stratum; hot air rises rapidly from the sand, cold air pours down to take its place. Strata of air of different densities lie over, and in-
*(Compare this with the accepted explanation. Is it correct?)