PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 
695 
from the deeper strata, by its opacity to this process (p. 694), that the water only a 
meter or two down would lose heat much less rapidly than happens in reality, so 
that the 20 to 30 meter level probably would not show enough cooling during the 
winter months for the change in temperature to be measurable on our ordinary deep- 
sea thermometers. 
Actually, however, vertical circulation is most active during the cold half of the 
year; consequently, the mixing of the various strata of water is constantly bringing 
up fresh water from below, to radiate its heat out into the atmosphere. The fact 
that the upper 100 meters, or so, cools off so uniformly during the winter, instead of 
only a thin surface film, is therefore wholly the result of convectional movements 
■of the water particles, induced either mechanically (by winds or tides) or djuiami- 
■cally, if the surface water so chills that it becomes heavier than the underlying layer, 
which, however, seems never to take place in the open gulf (p. 929). 
The rigorous climate of northern New England and of the Canadian Province 
of New Brunswick so profoundly influences the sea temperature of the Gulf of 
Maine that the following tables of the air temperatures at stations bordering the 
gulf may be of interest. 74 
Normal air temperatures ( Fahrenheit ) 
Month 
Locality 
Janu- 
ary 
Febru- 
ary 
March 
April 
May 
June 
July 
August 
Sep- 
tember 
October 
No- 
vember 
De- 
cember 
Boston 
27.0 
28.0 
34.5 
45.3 
56. 6 
65.8 
71.3 
68.9 
62.7 
52.3 
41.2 
31.6 
Portland 
22.0 
23.8 
32.0 
43.0 
53.5 
62. 6 
68.0 
66.2 
54.2 
49. 1 
37.6 
27.1 
Eastport 
20. 1 
20.4 
28.9 
38.3 
48. 9 
54. 4 
59.8 
59.7 
55.2 
46.6 
36.8 
25.3 
Mean winter temperatures °F, with departures from normal ( J . IF. Smith, 1913-1921 ) 
1911-12 
Locality 
December 
January 
February 
March 
Temper- 
ature 
Depar- 
ture 
Temper- 
ature 
Depar- 
ture 
Temper- 
ature 
Depar- 
ture 
Temper- 
ature 
Depar- 
ture 
Boston 
21. 4 
-5. 6 
27.7 
-0.3 
36.0 
+ 1.0 
Portland 
15.3 
-6.7 
23.2 
- .6 
30.2 
-1.8 
Eastport 
14.3 
-5.8 
20.4 
-1.0 
28.8 
- .i 
1912-13 
Boston 
38. 5 
+ 6.9 
+5. 2 
39. 3 
+ 12. 3 
27. 7 
-0. 3 
42. 4 
Portland 
32. 3 
31. 6 
+ 9. 6 
21. 0 
-2. 8 
35. 2 
Eastport 
28. 7 
+3.4 
27.8 
+ 7.7 
17.2 
-4.2 
32.0 
1914-16 
Boston 
30.4 
-1.2 
33.0 
+6.0 
33.2 
+ 5.2 
35.8 
+0. 08 
Portland 
24.4 
-2.7 
26. 4 
+ 4. 4 
28.4 
+4.6 
32.2 
+ .02 
Eastport 
23.6 
-1.7 
24.6 
+ 5.5 
27.6 
+ 6.2 
29.9 
-1.00 
74 From the U. S. Weather Bureau. 
