Winter operations, 1970-1971 / John C. Ayers, Norbert W. O'Hara, William L. Yocum.

induced components of plume movement from these directions are so nearly
parallel to shore that they probably can be considered as parallel.
It is evident that the Cook Plant's plume of waste heat will be blown toward
shore by winds from several westerly and northwesterly directions. At the same
time its direction will be modified by whatever alongshore current has been developed by the preceding wind. The wind-induced component and the alongshore
current component are both variable and usually varying; the resultant of the
vector addition of the two components at any instant determines the net direction of the plume movement at that time. Under varying westerly or northwesterly
winds, and varying alongshore currents the Cook plume would wander randomly north
and south of the plant site. Where the plume meets shore ice it can be expected
to initiate the melting of the ice.
Because both the components influencing the movement of the plume will usually be varying, the resultant of their addition will seldom be the same; the result will usually be a plume-to-ice contact that is constantly shifting position.
It cannot, under these conditions, be expected that the shore ice of any one
local area will be subject to the waste heat of the plume for more than short
periods of time. Once the plume is out of contact with the local ice the normal
winter regimen of the lake will resume; this includes both ice-destruction and
ice-building.
Before proceeding further in this discussion it is necessary to point out
that Figure 21 contains circles of wind frequency representing all the hours of
winter wind observed during three years of observation at the Cook Plant site.
Reading from the wind rose, the most frequent westerly wind is that from the 280~
decade of wind directions; from this decade of direction (280~ to 290~) the wind
blows about 5.5% of the time. Similarly the most frequent northwesterly wind
comes from the 310~ direction decade about 5% of the time.
We judge that winds from 240~ around to 340~ can produce significant onshore
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