414 
BULLETIN OF THE BUREAU OF FISHERIES 
The summer heat income ranged from 16,000 calories on August 13, 1927, to 
21,200 calories on August 15, 1926. The mean summer heat income for the four 
August and September observations is 18,900 calories. 
The gain of 5,800 gram-calories between July 10 and September 3, 1928, repre- 
sented an average daily gain of a little more than 105 gram-calories for this period 
of 55 days. The gain between July 19 and August 13, 1927, was about 96 calories 
per day, while that between July 9 and September 8, 1929, was only 68 calories 
per day. 
Table 5. — The mean temperature, heat budget, summer heat income, and gain in heat between the two 
dates on which summer temperature observations were made on Karluk Lake 
[The results for heat are indicated in gram-calories per square centimeter of surface] 
Date 
Mean 
tempera- 
ture, °C. 
Heat 
budget 
Summer 
heat 
income 
Gain in 
Total 
: heat 
Average 
per day 
Aug. 15, 1926 ----- 
8. 37 
35, 800 
21, 200 
July 19, 1927 
6.80 
28, 200 
13, 600 
Aug. 13, 1927 - - 
7. 30 
30,600 
16,000 
2,400 
96 
July 10, 1928 
6. 84 
28, 400 
13, 800 
Sept. 3, 1928 
8.03 
34, 200 
19, 600 
5,800 
105 
July 9, 1929 - 
7. 02 
29, 200 
14, 600 
Sept. 8, 1929 - - 
7.87 
33, 400 
18, 80(f 
4,200 
68 
July 12, 1930 
7.00 
29, 100 
14, 500 
The mean of the August and September heat budgets of Karluk Lake in 1926 
to 1929, inclusive, is 33,500 gram-calories. This budget is comparable in size to 
those of a number of lakes situated in much lower latitudes, such as Green Lake, 
Wis., and some of the Finger Lakes of New York, as well as some of the European 
lakes. The heat budgets of several American and European lakes are given in Table 6. 
These data show that the average heat budget of Karluk Lake is exceeded some- 
what by those of some of the larger lakes represented in the table, such as Seneca, 
Cayuga, and Owasco of New York, Geneva of Switzerland, and Loch Ness of Scot- 
land, but the 1926 budget of Karluk almost or quite reaches that of some of the 
members of this group. The averages for Karluk and Green Lake are substantially 
the same, as well as that of Traun See of Austria. Four of the lakes included in the 
table have smaller heat budgets than Karluk Lake. While the temperature of the 
upper water of Karluk Lake is not as high as that of Green Lake, Wis., and of the 
Finger Lakes of New York, yet its area and depth are such that it absorbs a similar 
amount of heat per unit of area during the warming period each year, as indicated 
in the table. 
Table 6. — Heat budgets of some American and European lakes 
Lake 
Location 
Heat 
budget, 
gram- 
calories 
Lake 
Location 
Heat 
budget, 
gram- 
calories 
irorlMlr 
Alaska 
33,500 
34,000 
36, 700 
37, 400 
35.600 
36.600 
Zurich 
Switzerland 
21,800 
26,000 
33,400 
32,000 
37,200 
31.500 
Green " * 
Wisconsin 
Wiirm 
Germany 
SpnppR _ _ 
New York 
Traun 
Austria 
Cayuga 
Vettern... 
Sweden 
do 
Scotland 
Geneva 
Switzerland 
TiOuhy 
do 
