Studies on water movements and sediments in Southern Lake Michigan : part 1[-3] ... / by John C. Ayers.

May. Off Chicago the most intense thermal and density stratification occurs in late August and involves only the upper
isotherms of the lake's thermocline, the rest of the thermocine being intercepted by the bottom.
The bottom water off Chicago in the period of greatest
stratification is mid-thermocline water; in the absence of
internal waves typical two-layered flow is unlikely at this
period.
In June a two-layered water column exists temporarily
while the thermocline is developing but has not yet reached
bottom; this appears to be the time of year when significant
directional differences between surface and bottom currents
(in the absence of internal wave activity) might occur if
local development of a two-layered water column were the most
important factor.
Internal wave activity, by tilting the thermocline and
intruding colder subsurface water into the area, can establish
temporary two-layered conditions with possible differences in
top and bottom current directions regardless of the condition
in the undisturbed local water column.
In the absence of internal waves the general condition
off Chicago appears to be that surface and bottom currents
would move in more or less the same direction during nearly
all the year. The movements of the few successful deeper
drogues off Chicago are in agreement with this conclusion.
Crude Estimates of Dilution off Chicago
While the drogue runs off Chicago were intended primarily

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