waters were, of course, much warmer than 

 those of June as demonstrated by the bot- 

 tom temperatures that ranged from 8.5° to 

 11.4° (47,3° to 52.5° F.) in the fall and 

 from 6.2' to 6.6° (43.2° to 43.9° F.) in 

 the spring. 



As the waters begsin to cool in the 

 fall the temperatures approached uniform- 

 ity at all depths as indicated by the 

 difference between the bottom and surface 

 temperatures which averaged 7.4° (13,3° 

 F,) during September 21-25 and 3,0° (5,4° 

 F,) during September 30-October 4. On the 

 last date the temperatures ranged from 

 10,2° (50.4° F.) at the bottom to 12.6° 

 (54.7° F.) at the surface. This reduction 

 of temperatures eliminated the thermocline 

 that had shifted in September between 8 

 and 25 meters (26 and 82 ft.) and between 

 15.3° and 8.9° (59.5° and 48.0° F.) , 

 although it had covered a range of only 

 about 3 meters (10 ft.) in depth and 3° 

 to 5° (5* to 9° F.) that averaged 3.5° 

 (6.3° F.). 



COMPARISONS BETWEEN THE DATA OF 

 1932 AND OF 1930 AND 1931 



In order to determine 

 whether the data of 1932 dif- 

 fered very much from those of 

 1930 and 1931, the records of 

 adjacent areas should be com- 

 pared for about the same time of 

 the year. The Upper Lake Michi- 

 gan data of 1932 should then be 

 compared with the records of 

 1930 and 1931 that were obtained 

 in the areas off the Ludington- 

 Frankfort and Manitowoc-Kewaunee 

 shores. The number of records 



greater 

 1932. I 

 greater 

 eral ave 



is shown in parentheses. 



The surface temperatures 

 of the shallow cind deep waters 

 averaged higher in 1932 than in 

 1930 and 1931 during the compcir- 

 able periods of June-September, 

 except in July when the tempera- 

 tures of both waters averaged 

 higher in 1931, not in 1930, 

 than in 1932. The general aver- 

 ages are shown in the left 

 table. 



The average depths of the 

 5-degree (41° F.) water were 

 in June of 1930 and 1931 than in 

 n the other months the depths were 

 in 1932 in both waters. The gen- 

 rages are shown in the table below. 



The monthly 

 the deep stations 

 0,1° (0,18° F,) 



1930 and 1931 dur 

 (0.72° P.) higher 

 than in 1931. I 

 peratures of the 

 0,25° (0,45° F ,) 



1931 in June but 

 in July and 1,05° 



bottom temperatures of 



averaged consistently 

 higher in 1932 than in 

 ing June-August and 0,4° 



in September in 1932 

 n general the 1932 tera- 

 shallow stations averaged 



lower than in 1930 and 

 0,25° (0,45° F.) higher 



(1,89° F,) in August, 



The monthly average depths of the 

 thermoclines were consistently greater in 

 1932 than in 1930 and 1931 as shown in the 

 upper table on page 33, 



The monthly average temperatures of 

 the 1932 thermoclines were approximately 

 the same as those of 1930 and 1931 during 

 the months when comparable data were avail- 

 able. The tabular materials are shown in 

 the lower table on page 33. 



32 



