WEATHER 



The following weather diagrams are based upon the observations 

 recorded in the General Greeners log book. They have been con- 

 structed in the same way as the diagrams published in previous ice- 

 patrol bulletins. 



The area in which the patrol vessel operated can most readily be 

 seen by referring to the surface temperature maps on which the track 

 of the General Greene is plotted. It should not be forgotten that the 

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

 southern portion of it will undoubtedly have, in the long run, much 

 warmer weather and less fog than one in the central or northern por- 

 tions. 



The weather diagrams give information about barometric pressure, 

 visibility, and wind. Inner figures show day of the month; the next 

 band out contains a record of the atmospheric pressure in inches of 

 mercury; the next outer one indicates the degree of visibility. Black 

 areas here represent visibility of 4 and less on the international scale 

 to 9 (less than 2 sea miles). Cross-hatched areas indicate visibility 

 5 and 6 (between 2 and 4 sea miles). White areas indicate good 

 visibility of 7, 8, and 9 on the international scale. The outer margiiis 

 of the diagrams show the average direction and force of wind per 12- 

 hour periods, midnight to noon, and noon to midnight. Wind direc- 

 tions are toward the small black dot in each case. Large arrow 

 indicates true north for wind directions. 



Maximum and minimum air temperature and mean air temperature 

 is also given for each cruise. The mean temperatures were obtained 

 simply by adding the air temperatures recorded every hour and 

 dividing by the number of observations. 



The barometer on board the General Greene was an ordinary aneroid 

 barometer. It was checked several times during the ice season by 

 comparison with mercurial barometers ashore. The thermometer 

 used was an ordinary ship's air thermometer that was rather poorly 

 exposed on the foremast just forward of the bridge. 



(27) 



