[NLRS] 10 GHz & the Great Lakes

[W0ZQ@aol.com]

In looking at Lake Michigan, it sure has a nice long shot from north to 
south, but, does/can it have the enhancement like we have seen across Lake Superior 
?   Perhaps if we had a better handle on what caused the great 10 GHz 
propagation that we had last August across Lake Superior we may have a better answer 
to that question.    

Regarding that great propagation, I still like the theory that the lake 
itself being cool causes a regional inversion when those hot August dog days occur. 
  Regarding data, the Great Lakes Surface Environmental Analysis (GLSEA) 
website has some nice weather data to scan through.   From that website, one table 
has the daily average surface water temperature for all five Great Lakes for 
that last 365 days.   From this data, on Saturday, August 16 (during the 10 
GHZ contest), the average surface water temperature for Lake Superior was 62.3 
degrees F while Lake Michigan was 10 degrees warmer at 72.2 degrees F.   Given 
the same air temperature over both lakes during the dog days of August of say 
90 to 95 degrees, Lake Superior can generate a significantly larger 
temperature gradient (inversion) than can Lake Michigan.

On Sunday, August 17, Lake Superior's average surface temperature went down 
nearly five degrees to 57.8 degrees F while Lake Michigan stayed nearly the 
same at 71.9 degrees F, or a 14.1 degree F difference (between the two lakes).   
I was wondering why Lake Superior's average surface temperature should take a 
five degree drop in one day and then I remembered the wind .... for those who 
were along the MN north shore on Sunday, remember the wind ?   Is it possible 
that the wind churned the lake such that it brought up cold water from down 
deeper .... Lake Superior is much much deeper than Lake Michigan and its core 
must stay significantly colder.

So, just to throw out more theory, 

1) For a given fixed air temperature over all the Great Lakes, Lake Superior 
should generate much better microwave propagation than Lake Michigan or any of 
the other Great Lakes simply due to the fact that it remains colder (due to 
its depths).    Being colder produces stronger temperature gradients over the 
lake (ie; inversion).
2)  Wind is good if for nothing else than to bring that colder water to the 
surface to chill the air down low to establish a better temperature gradient 
(inversion) on those August dog day (cold down low, hot up above).

Has anyone tried to work across the long north/south (not east/west) Lake 
Michigan path ?    If so, what time of year was it and how strong were signals ?  
 If they tried and failed then perhaps Lake Michigan is too warm (for 
ducting).

73, Jon
W0ZQ


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