69 



The month was quite a pleasant one, taken as a whole. Air tempera- 

 tures were quite low due to the unusual coldness of the ice-bearing 

 waters, but there was much bright sunshine, and the air and sea 

 temperatures slowly rose as the month advanced. 



A few large cyclones passed northeastward across Newfoundland 

 and Labrador, but the patrol vessels escaped all but the southern edges 

 of these, and so had only two 12-hour periods of gales and no baro- 

 metric pressure lower than 29.62, which figure was reached on the 

 last day of the month. One feature noted on the weather maps made 

 on board from synoptic data was a succession of large high-pressure 

 areas that moved southeastward across the United States Atlantic 

 Coast States and out to sea to join the Azorean High. Barometric 

 pressures in the ice-patrol area became very high at times, exceeding 

 30.50 on five different days, which were invariably fine and sunny, 

 though on two of these five days there was a slight haze that made 

 bergs appear yellowish in the distance and disappear from sight when 

 from 8 to 10 miles distant. Phenomenal visibilit}^ prevailed on the 

 2d, however, when the barometer was at 30.22 and light variable 

 airs were blowing. At this time a berg about 50 feet high was seen 

 from a height of eye of 30 feet when it was 38 sea miles distant. 



The short period of fog experienced on the 11th with a high and 

 rising barometer and north-northwest breezes was most unexpected. 

 It occurred just before sunset over cold water near the junction of the 

 Labrador Current and the Gulf Stream. The line of demarcation 

 between the two waters was very ragged, for a little earlier in the day 

 the patrol had cruised though alternate areas of cold and warm water 

 each about 2 miles wide. The fog can best be explained by assuming 

 that the surface air had just passed over a warm band of water and 

 become moist and warm. A cold band of water happened to be to 

 leeward of the warm band and, the critical conditions being just right, 

 the moisture in the north-northwest breeze was condensed as fog 

 as soon as the lowest layers of tbe warmed moistened air were chilled 

 by contact with the small cold area in the sea. This unusual local 

 fog occurred again on the 21st under almost identical conditions, 

 except that in the second case the barometer was even higher, about 

 30.50 throughout the time. With northerly breezes fog is sometimes 

 formed over the warm water, but its presence over cold water was 

 very hard to explain. 



Many other interesting meteorological phenomena were observed. 

 For instance, the weather diagram shows that fog was finalh' caused 

 on the 19th after southeasterly airs had been blowing for some time. 

 As a general thing it takes a considerable time for southerly bieezes 

 to bring on a period of fog, and the further advanced the season is and 

 the warmer the surface water is the harder it seems to be for the thick 

 weather to get started. 



