32 



Azorean high; and (c) the continental effect of bordering land areas. 

 Glancing at the normal isobaric map of the North Atlantic for the 

 colder months of the year, the station normals of which are based 

 upon average barometric records compiled over a long series of years, 

 our eye is immediately caught by a huge elliptical-shaped depression 

 near Iceland. And then we notice that in effect this depression is 

 emphasized by the opposing anticyclonic conditions which prevail 

 over the bordering land masses of the Atlantic basin. The geograph- 

 ical position of the Grand Banks in the western North Atlantic on 

 the southwestern side of this mammoth cyclonic wind system, it is 

 plain to see, subjects the iceberg regions south of Newfoundland to 

 an air stream flowing from west to east, the swiftness of which is gale 

 force the major part of the early season. Such prevailing circulation 

 is, however, often subjected to short interruptions when cyclonic 

 storm centers usually of marked intensity come from the United 

 States and cross the ice regions. Now, during the latter half of the 

 ice season the unequal rale of solar warming between land and water 

 causes the wintertime high pressure to transfer from the land and 

 increase over the ocean, thereby placing the Grand Banks region on 

 the northwest side of a huge clockwise wind system. Gradients 

 also become much reduced in steepness from what are found in winter 

 season, and the warm southerly winds blowing over the icy waters 

 around the Grand Banks bring a fog sheet which often does not lift 

 for weeks at a time. This comprises a general survey of the two main 

 types of weather and incidently it emphasizes two of the greatest 

 handicaps the patrol is forced to encounter, namely early season 

 gales and later season fogs. 



If we return to a survey of the 1926 ice season we find no features 

 of especial significance beyond the continuance of cyclone and anti- 

 cyclone in alternate sequence following each other across the meteor- 

 ological map from west to east, and in general with the progress of 

 the season, gradients becoming gentler, winds weaker, and vortices 

 traveling slower. 



An interruption in the regularity of undulations to which the trop- 

 osphere was subjected by alternate "highs" and "lows," occurred 

 May 27 to June 2, when a great anticyclone built up and spread over 

 the entire Atlantic seaboard from Florida to Newfoundland. It is 

 rare to have such an atmospheric distribution but it means clear 

 visibility and northerly winds for the ice regions; really the best 

 weather we get on patrol. 



DEVELOPMENT OF SUMMER TIME CONDITIONS 



Going into June we began to notice the gradual development of 

 the summer time Azorean high pressure as the thermal seesaw swung 

 the opposite way from that observed at the beginning of the ice season. 



