1. Ahmed, A. K., Environment, 17, 6 (1975).
2. Roosen, R. G., Angione, R. J., and Klemcke, C. H., Bull. Am. met. Soc., 54, 307 (1973).
3. Vigroux, E., Ann. Phys., 8, 709 (1953).
4. Thomas, R. W., Guard, K., Holland, A. C., and Spurling, J. F., NASA Technical Note TN D-7758 (1974).
5. Dobson, G. M. B., Q. Jl R. met. Soc., Suppl., 62, 52 (1936).