22 



exactly as it has appeared in this series of bulletins for a number of 

 yeare. Such uniformity will aid future investigators who may desire 

 to study the patrol's weather conditions for any purpose. 



The area in which the patrol vessels themselves operated can most 

 readily be seen by referring to Figure 1. It should not be forgotten 

 that the area of operations is a region of strong contrasts. A vessel 

 in the southern jiortion of it will undoubtedly have much warmer 

 weather and less fog than one in the northern portion. The ice-patrol 

 vessels must, in general, remain near the southern limits of the ice. 

 It is therefore the average weather of this varying limit that is 

 described and tabulated here. 



The weather diagrams for each month give at a glance the wind 

 directions and forces averaged for every 12 hours, the barometric 

 curve, and the time and duration of fog and low visibility. Maximum 

 and minimum and average surface-air temperatures are given for 

 each month. The average air temperatures were obtained by adding 

 all the daily maxima to all the daily minima and dividing the sum 

 by twice the number of days. The scientific value of all the tem- 

 perature values is mitigated by the mobility of the patrol vessels about 

 the Tail of the Grand Banks, and by the fact that ordinary poorly 

 exposed ship's air thermometers were used in making the observa- 

 tions. It is believed that the values will be of interest, however, in 

 showing about what temperatures should be expected and prepared 



for on ice patrol. 



FEBRUARY 



Maximum air temperature, 44° F. 



Minimum air temperature, 25° F. 



Average air temperature, 33.3° F. 



Visibility was less than 4 miles 10.6 per cent of time. 



Visibility was less than 2 miles 3 per cent of time. 



The ice patrol was active in the Grand Banks region during the 

 last 15 days of February. The weather was cold, but surprisingly 

 clear, with moderate winds. Three major atmospheric depressions 

 affected the barometer, but only the last of these were accompanied 

 by winds of gale force. 



Figure 11 shows graphically a number of the main meteorological 

 elements. The wind forces and visibilities on all the weather diagrams, 

 Figures 11-15, are based on the tables printed in the latest editions of 

 the American Practical Navigator of the United States Hydrographic 

 Office. 



