Could be this?:  

https://en.wikipedia.org/wiki/Tropospheric_propagation  

Kelly Black
KB0GBJ   
>  Mon Aug 31 2015 08:18:00 AM CDT from "Tom" <tompoe at meltel.net>  Subject:
>Re: [tclug-list] ota signal snafu question
>
>        
>  Hi, Rhubarbpieguy:  Nice to know I'm not alone.  I'm located in Eden
>Valley.  My OTA antenna is a DIY 8-bay with 9 1/2" whiskers, along with
>pre-amp setup.  Rescan has not corrected the issue.  Currently getting ABC
>out of Chicago where I expected CBS out of Minneapolis (72 miles).  What
>antenna are you using?
> Tom
> P.S.  I am a big rhubarb pie fan as well.  :)
> 
>  On 08/31/2015 07:53 AM, rhubarbpieguy at gmail.com wrote:
>
>  
>>  
>> 
>> On 08/31/2015 06:01 AM, Tom wrote:
>> 
>>
>>  
>>>This weekend, antenna reception was weird.  By Monday morning, I got poor
>>>to nonexistent reception across the spectrum.  Interestingly, my channel 7
>>>CBS is now channel 7 ABC.  Has anyone noted any discussion about Minnesota
>>>tv farm changes taking place?
>>> Tom
>>>   --   John Washington emigrated from England in 1656 to Colony of
>>>Virginia.  It's time George Washington is issued his Green Card.    
>>>
>>>  _______________________________________________  TCLUG Mailing List -
>>>Minneapolis/St. Paul, Minnesota  tclug-list at mn-linux.org 
>>>http://mailman.mn-linux.org/mailman/listinfo/tclug-list    

>>  
>> Somewhat OT, but I also noticed anomalies.  I consistently receive
>>signals from 90 miles away.  However, yesterday I lost channels from the
>>fringe but received several from 220 miles away.
>> 
>> This morning I noticed three misidentified channels.  Misidentification
>>happens occasionally.  Does rescanning correct you CBS and ABC displays?
>> 
>>
>>  _______________________________________________  TCLUG Mailing List -
>>Minneapolis/St. Paul, Minnesota  tclug-list at mn-linux.org 
>>http://mailman.mn-linux.org/mailman/listinfo/tclug-list    

>  
>  --   John Washington emigrated from England in 1656 to Colony of Virginia.
> It's time George Washington is issued his Green Card.          
>  
>
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