Dean Norris wrote:
>
> At 06:53 1/7/97 -0800, you wrote:
> >
> >
> >"At the time (local) half way between local sunrise and local sunset,
> >the Sun, if shining, will cast a shadow exactly (true) North-South."
> >
> >That's the sentence.
> >
> >Now, to avoid the FLAMES I received last time: No, I do not mention
> >NOON and this has nothing at all to do with noon, anywhere. Yes, this
> >works in the Southern Hemisphere, the shadow will fall to the South,
> >however. Yes, this works in Alaska (when the sun is out). Yes, if you
> >live in Death Valley or behind a hill, you won't be able to use this.
> >And finally, no, it will not work on the Moon, and it will be difficult
> >on/near the Earth's Equator.
> >
> >Example:
> >
> >local sunrise = 0700
> >local sunset = 1720
> >
> >The sun will cast a shadow N-S at exactly: {(1720-0700)/2} + 0700 =
> >1020/2 + 0700 =
> >510 + 0700 = 1210 local time!
> >
> >Just use the local weather forcaster's sunrise/sunset times and it's
> >accurate for amateur antenna alignment for sure!
> >
> >73!
> >
> >Bill, N3RR
>
> Bill,
>
> I live in a location where the takeoff angle to horizon to the east is
> virtually zero degrees, in other words, straight out. To the west the
> horizon is blocked by tall mountains and the takeoff angle is probably 20
> degrees. Will this make a difference to the sunrise and sunset times.?
>
> Don't flatlanders have it easy!
>
> C. Dean Norris, K7NO
> e-mail to dnorris@k7no.com
> Have you hugged your criminal defense attorney today?
I don't think so, because the sunrise and sunset times should assume 0
Degrees to the horizon from some local location. Once the sun comes up
above local obstructions, it's then visable and casting shadows. As
long as those obstructions are not TOO close to the object (your
tower??) and obstruct the shadow undergoing measurement, this will work.
Bill, N3RR
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