[TowerTalk] ridge top derating factors

[Guy Olinger, K2AV]

The layering of air at different temperatures is a common phenomenon
climbing towers. It is also true that the layers will sometimes move in
different directions. This was the case when I lived in Northern Va. as
K4VDL. In the fall late afternoons, the lower, colder layer was moving
(sinking) toward the lowest point, northeast. The light breeze above the
colder air was moving toward the southeast. The direction of the upper
air was what the flight service stations were quoting as "winds aloft".
The break point was about 50 feet off the ground. The temperature
difference must have been twenty degrees.

When I rode a motorcycle in the fall, going down a hill you could drive
into a colder air pocket that would really cool you down. There was one
valley spot north of New York city where the Taconic parkway crosses US
6 (Jefferson Valley) where the temps on the bank sign could be 15
degrees below what the TV was reporting. Sometimes it was so much colder
and dryer than the upper air that visors and windshields would fog over
when you drove back up into the warmer air.

None of the above would occur though, if there was any significant
prevailing wind.

With respect to working for a long time up on a tower, it may be much
warmer at the top. I wear a short-sided sweater over the full-body
harness, so I can get it off if needed.

- - . . .   . . . - -     .   . . .     - - .   . - . .

73, Guy
k2av@contesting.com
Apex, NC, USA

----- Original Message -----
From: Eric Gustafson <n7cl@mmsi.com>
To: <towertalk@contesting.com>; <jlangdon@outer.net>
Sent: Saturday, April 15, 2000 2:04 PM
Subject: Re: [TowerTalk] ridge top derating factors


>
>
> Hi John,
>
> I have a photograph that I took at one of our customer's mines in
> South Africa.  They have a smelter with three smoke stacks.  Each
> stack is about 50 to 75 feet taller than the next smaller one.
> the picture clearly shows the smoke streams going out in an
> almost perfect 120 degree spoke pattern away from the smelter
> (for miles).  We were there for about 5 weeks and the smoke
> pattern was as described above more than 50 % of the time.
>
> 73, Eric  N7CL
>
> >From: "John Langdon" <jlangdon@outer.net>
> >Date: Thu, 13 Apr 2000 15:13:51 -0500
> >
> >Just an unscientific observation, but I am on a not very high
> >ridge, but I have seen the antennas on the tower (at various
> >heights up to 195') deflecting in two different directions from
> >each other and both different from what the prevailing winds
> >were on the ground, and I have also started up the tower in
> >relative calm at the ground level and decided not to work
> >because the winds were too much at 90', and found it still calm
> >when I got back down to the base of the tower again. Never
> >boring!
> >
> >73 John N5CQ
> >
>
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>


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