PHYSICAL OCEANOGRAPHY OP THE GULF OF MAINE 
685 
As every coastwise navigator knows, there is much less fog along the western 
shore of the gulf from Cape Cod to Cape Elizabeth than there is at the mouth of the 
Bay of Fundy. Consequently, the former is exposed to more hours of direct 
sunlight, tending to accentuate the difference in temperature resulting from differ- 
ences in latidude, per se. On the other hand, winds from the quadrant between west 
and south, such as prevail over the Gulf of Maine during July and August (p. 965), 
tend to drive the warmed surface water eastward toward Nova Scotia, thus trans- 
ferring heat from southwest to northeast (with more or less colder water welling up 
along the western shore), and so in part to counteract the difference in the rate of 
solar warming which would otherwise accompany the difference of latitude. With 
a “run” of easterly winds the direction of surface drift will be reversed. Thus, it is 
by no means a simple task to account for variations in the mean temperature as 
narrow as those prevailing between different parts of the Gulf of Maine in the 
summer months. The much wider regional variations in surface temperature or in 
the temperature of the water at any given level below the surface follow much 
more obvious causes. 
I think it sufficiently established, however, that the difference between the mean 
temperature of the column of water (in other words, its potential temperature) in 
the northeastern part of the gulf and in the southwestern part is not greater in most 
summers than can be accounted for by the difference of latitude and by such other 
local causes as fog, the direction of the wind, and the regional difference in the ac- 
tivity of the vetical tidal mixing, on which too much stress can hardly be laid. 
This is still more certainly the case in winter, when the temperature of the gulf 
is so nearly uniform, vertically, that station for station comparison of the actual 
readings at once reveals any regional differences in the mean temperature. 
In winter it is only close along shore that any unmistakable difference between 
the northeastern and southwestern parts of the gulf can be demonstrated, and this 
is not wider than can be accounted for by the difference in latitude. 
Winter temperatures at representative stations during the cold months, ° C. 
• 
Locality, date, and station 
Surface 
40 meters 
100 meters 
Western side - 
Off Boston Harbor, Dec. 29, 1920, station 10488 _ 
3. 90 
5. 34 
Off Gloucester, Dec. 29, 1920, station 10489 
5. 56 
6. 94 
6. 97 
Off Gloucester, Mar. 1, 1920, station 20050 __ 
2. 50 
1. 89 
1. 52 
Eastern side: 
Yarmouth (Nova Scotia) sea buoy, Jan. 4, 1921, station 10501 
3. 80 
3.86 
Off Lurcher Shoal, Jan. 4, 1921, station 10500 
5. 83 
6. 17 
6. 70 
Off Mount Desert Island, Mar. 3, 1920, station 20056 
1. 15 
.49 
1.95 
The foregoing discussion leads to the conclusion that the cold water from the 
Nova Scotian current is soon so thoroughly incorporated with the water of the gulf, 
after the flow past Cape Sable slackens, that in most years the regional disturbance 
of temperature which it causes at first is entirely dissipated by June. Even in years 
when the longshore drift continues to pass Cape Sable until late in the summer 
(p. 834), it may, at the most, hold the mean temperature a degree or two lower along 
western Nova Scotia until July than it is out in the neighboring basin of the gulf. 
After that (earlier still in “early” seasons) the surface water contributed by this 
