Month 



Depth in 



meter 

 and feet 



Average depths of the thermoclines 



1930 



1932 



1931 



1932 



11.0-13.0(2) 13.0-15.0(3) 



36.1-42.6 42.6-49.2 



18.0-24.0(3) 13,3-18.0(8) 19.8-25.2(4) 



59.0-78.7 43.6-59.0 65.0-82.7 



16.3-19.6(3) 21.5-26.0(10) 14.2-18.2(11) 20.9-25,6(14) 



70.5-85.3 46.6-59.7 68.6-84.0 



13.0-17.3(3) 22.2-26.9(7) 



42.6-56.8 72.8-88.2 



The data indicate that the waters of 

 the upper lake were generally warmer during 

 midsummer at all depths in 1932 than in 

 1930 and 1931 in the adjacent lower regions. 



The Green Bay bottom temperatures 

 were noticeably higher than those of north- 

 ern Lake Michigan during the comparable 

 periods of the year. The temperatures of 

 the period, September 18-October 5, aver- 

 aged Q.a^O) (48.6° F.) in 1930 in Green 

 Bay and 4.0° (3) (39.2° F.) in 1931 off the 

 Kewaunee and Ludington shores. During the 

 periods of May 13-21 and June 6-15 the 

 temperatures averaged 5.9° (9) (42.6° F.) 

 in 1932 in Green Bay, 3.8° (4) (38.8° F.) 

 in 1931 off the Ludington shore, and 4.0° 

 (9) (39.2° F.) in 1932 in Upper Lake Michi- 

 gan. 



The surface temperatures of Green Bay 

 were also higher in 1932 than those of 

 northern Lake Michigan during the spring 

 periods, but lower in the fall of 1930. 

 The fall temperatures averaged 14.2° (3) 

 (57.6° F.) in 1930 in Green Bay and 18.0° 

 (3) (64.4° F.) in 1931 off the Kewaunee 

 and Ludington shores. The May temperatures 

 averaged 6.5° (5) (43.7° F.) in 1932 in 

 Green Bay and 4.0°(2) (39.2° F.) in 1931 

 off the Ludington shore. The June tempera- 

 tures averaged 14.3° (4) (57.7° F.) in 1932 

 in Green Bay, 7.0''(2) (44.6° F.) in 1931 



off the Ludington shore, and 11.1° (9) 

 (52.0° F.) in 1932 in Upper Lake Michigan. 

 The relatively shallow and enclosed waters 

 of Green Bay may account for its noticeable 

 variation from the northern Lake Michigan 

 temperatures during the spring and fall. 



LITERATURE CITED 



AVERS, JOHN C. 



DAVID C. CHANDLER, 



GEORGE H. LAUFF, CHARLES F. POWERS, 



AND E. BENNETTE HENSON. 

 1958. Currents and water masses of Lake 

 Michigan. Great Lakes Research 

 Institute, University of Michi- 

 gan, Publication No. 3, 169 pp. 



CHURCH, PHIL E. 



1942. The annual temperature cycle of 

 Lake Michigan. I. Cooling from 

 late autumn to the terminal point, 

 1941-42. The University of Chicago 

 Institute of Meteorology, Miscel- 

 l£Uieou5 ReportF, No. 4, 51 pp. 



1945. The annual temperature cycle of 



Lake Michigcin. II. Spring warm- 

 ing and summer stationary pe - 

 riods, 1942. The Department of 

 Meteorology of the University of 

 Chicago, Miscellaneous Reports, 

 No. 18, 100 pp. 



33 



