as well as latest information supplied by recent military operations in the 

 arctic and antarctic. 



The illustrations are from a variety of sources and wherever possible are 

 new. Unless otherwise stated, the illustrations are taken from official U. S. 

 Navy photographs. Good pictures are not easily obtained in polar regions 

 because of the prevailing poor visibility, abundance of fog and clouds, low 

 elevation of the sun, and inaccessibility of the subject, combined with the 

 usual inexperience of the photographer with high latitude lighting con- 

 ditions. 



Acknowledgment for aid and photographs is made to: Dr. C. A. Barnes, 

 University of Washington; Major A. R. Gordon, Jr., USAF; E. C. LaFond, 

 U. S. Navy Electronics Laboratory; J. H. Roscoe, Directorate of Intelligence, 

 USAF; H. B. Washburn, Jr., Boston Museum of Science; and J. F. 

 Holmes, W. G. Metcalf, and M. J. Pollak, of Woods Hole Oceanographic 

 Institution. 



Acknowledgment is also made to the following sources for permitting 

 the use of copyrighted illustrations: 



International News Photos, New York City (Fig. 102) ; 



J. B. Lippincott Co., Philadelphia, from "The Home of the Blizzard" 

 by Sir Douglas Mawson (Figs. 80, 81, 84) ; 



Betty Love, Springfield, Mo., (Fig. 108) ; and 



Scott Polar Research Institute, Cambridge, England (21 illustrations 

 taken from Wright and Priestley) . 



Because of the limited period that any one observer will usually spend 

 in the polar regions, it is important that his preparation for what he may 

 see be in the nature of pre-experience. It is hoped that this publication will 

 provide much of this pre-experience and that all official ice observers will 

 acquire a thorough grasp of the material in this glossary before leaving 

 for the arctic or antarctic. 



VI 



