72 



an unstable area, where uprushes of air, indrafts, and such activities 



take place. 



JULY 



Maximum air temperature, 73° F. 



Minimum air temperature, 43° F. 



Average air temperature, 59.8° F. 



Visibility was less than 4 miles 38 per cent of the time. 



Visibility was less than 2 miles 32 per cent of the time. 



Previous to the 1929 season the ice patrol has always been dis- 

 continued by the middle of July, but the 1929 ice conditions neces- 

 sitated its continuance until August 3. The July meteorological 

 information given here and on the July weather diagram is, therefore, 

 for the first time that for the full month. The patrol was discontinued 

 so early in August that no separate discussion or weather diagram 

 has been prepared for the time after July 31. 



July was marked by very weak barometric gradients with accom- 

 panying fine moderate weather. The weather maps showed a tend- 

 ency for a low-pressure area to remain over the central portions of 

 North America and for high pressures to prevail over great areas of 

 the North Atlantic Ocean and over the United States Middle Atlantic 

 States. There was a marked increase in sea and air temperatures in 

 the ice-patrol area because of continued solar warming, and a falling 

 off in fog percentages as compared with the previous month. The 

 last three days of the month were days of dense fog because of per- 

 sistent southerly breezes and airs, and this fogginess was continued, 

 over the colder waters along the eastern edge of the Grand Banks at 

 least, without a break until after the patrol was discontinued on 

 August 3. This shows that an advanced summer season, while it 

 lessens the hours of fog over the warm and the warmed mixed waters, 

 has but little beneficial effect over the southern reaches of the Lab- 

 rador Current proper. It was often possible to pick clear-weather 

 areas and to remain in them by working toward cold-water areas 

 during northerly breezes and running toward warmer water when 

 southerly breezes began to cause fog. 



GENERAL REMARKS 



Because much interest is shown b}'' shipping in the patrol vessel's 

 weather, the conditions prevailing were always incorporated in the 

 routine ice broadcasts. Placing the data in these messages not only 

 assured as wide a dissemination of it as possible but saved time and 

 effort for all concerned through the cutting off of many inquiries 

 regarding weather conditions that experience has shown would 

 otherwise have come in from single vessels. 



Twice daily a coded weather report was dispatched to the United 

 States Weather Bureau, Washington, D. C, and at the end of each 



