I have been asked by your Council to address you to-night on one or more of the many points where aviation and meteorology come into contact. I cannot lay claim to much knowledge of aviation and my excuse must be the rapid increase of such knowledge during the last few years and the fact that under our present conditions much of it must be of a confidential nature; but the importance of meteorological conditions for the practical business of flying is so obvious and so great that I think it may be of use and interest to point out the effect that the more prominent meteorological phenomena have upon aviation.