“ppranee=~ Spades tt BECHER creating a net loss of radiation. This phenomena is of sufficient importance to warrant a closer study. Three quarters of solar radiation has wave lengths less than 1 micron, and at point of maximum intensity the wave length is less ian 0.5 micron. Terrestrial radiation has a wave length of approxin. aly 12 -..crons at its point of maximum intensity. . The cube of solar wave .sngth 1s mmall compared to the volume occupied by a volcanic dust particle which has a diameter of 1.85 micron, but the cube of terrestrial wave length is large compared io the same dust particle, Then, as Lord Rayleigi has shown, solar radiation will be diffusely reflected by the volcunis dust, but terrestrial radiation will be randomly scattered, I, ale Ey -Ee The following relations apply: -2np r* x 3 (for reflection)..........iqn 1 4 ~-lpnyV/a (for scatter). ..csccccesselGn 2. Where x and y are distances of uniformly dusty regions. I and E are initial intensities of solar and terrestrial radiation respectively. I, and are intensities after radiation has passed through a uniformly dusty region. n = number of particles in the dusty layer radius of particles r V = volume of a single particle at ~ & = wave length 3.1416 From Equations one and two we get y/x=2 a4 r*/ll p* Vv" = 30 approximately This means that a layer of volcanic dust of 1.85 micron diameter in the atmosphere is thirty fold more effective in shutting solar radiation out than it is in keeping terrestrial radiation in. This is in reality an inverse Greenhouse effect which would ultimately lower the equilibrium temperature of the surface of the earth if the dusty layer is maintained aloft indefinitely. Particles with diameters in the order of one half of sun's wave length or less shut out the solar radiation very much more effectively. This is because in the case of particles with such small diameters (0.2 micron or less) both solar and terrestrial radiation is 5008612 2 62-22190