70 



When fog is formed over the cold water it is often very thin ver- 

 tically with a clear blue sky showing overhead, as was the case on the 

 22d. Veiy often the rays of sunlight that reach the deck through 

 the fog around midday have considerable warmth left in them, but 

 not enough to remove the fog from the cold water as long as the wind 

 continues to blow from warmer water toward colder. When con- 

 ditions are rather finely balanced there is sometimes a tapering clear 

 lane over the sea for a quarter of a mile or more directly to leeward 

 of the drifting patrol ship, caused by the warmth escaping from the 

 stack and hull. 



The weather cleared slowly on the 23d after a shift of wind to the 

 northwest. By evening the atmosphere was remarkably clear to the 

 westward and sunset was followed by a very distinct green flash at 

 the spot on the horizon where the sun had just disappeared. The 

 next day, with its high barometer and gentle breezes, was about the 

 brightest, clearest, and finest day of the whole season. 



JUNE 



Maximum air temperature, 70° F. 



Minimum air temperature, 38° F. 



Average air temperature, 51.2° F. 



Visibility was less than 4 miles 42 per cent of the time. 



Visibility was less than 2 miles 34 per cent of the time. 



June, as is quite normal, had a higher percentage of hours with fog 

 than either of the two preceding months. There was a marked 

 change to general summer weather conditions. The procession of 

 "Lows" along the American coast and up the St. Lawrence Valley 

 slowed down, and a great high-pressure area in the ocean east of the 

 United States and southern Canada stood opposed to a fairly constant 

 condition of low pressure over North America. This distribution of 

 pressures always gives the Grand Banks region a large proportion of 

 gentle but steady southerly breezes, which are over the colder water 

 areas, accompanied by foggy weather. An even greater number of 

 times than during May there was low-lying fog with clear or partly 

 cloudy sky plainly visible overhead. The bright sunshine on some of 

 the days made fogbows and allied phenomena of common occurrence. 



When cruising along the temperature wall many areas of fog 

 patches were encountered. The search courses at such times fre- 

 quently changed the surface water temperatures 11° F. in 11 minutes, 

 say, from 48° F. to 59° F., and the air temperatures fluctuated almost 

 as much and as rapidly. It would be raw and foggy over the cold 

 water and damp and muggy over the warmer mixed water close by. 

 During the fir%t half of the month cold water pushed 150 miles to the 

 southeastward to '4(y° N., 46° 40' W., in a band about 20 miles wide. 

 This stream was very difficult to search for ice because winds from 



