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ZL3AI > APRDIG 17.12.03 10:49l 107 Lines 4061 Bytes #999 (0) @ WW
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Subj: TAPR Digest, Dec 14, 2/2
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Sent: 031217/0822Z @:ZL3VML.#80.NZL.OC #:14824 [Chch-NZ] FBB7.00i $:2500-ZL3AI
From: ZL3AI@ZL3VML.#80.NZL.OC
To : APRDIG@WW
Subject: Re: Strange Forecast
From: Dale Blanchard <wa7ixk@arrl.net>
Date: Sun, 14 Dec 2003 19:23:07 -0800
X-Message-Number: 7
But how do you turn that into something that technical people can understand.
Sounds like goblygook to me, and I have been around more than once in
this world.
But I am open to new things, I f you up to explaining to me.
I understand every thing in this world except what I do not understand
and that is the part I forgot because I am old.
> just got to spend a week with the genleman who's lead author on the
>website I listed above. I'm in awe of what he's done in numerical
>forecasting/prediction...
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Subject: APRS 300 baud scope
From: "Andrew Rich" <vk4tec@hotmail.com>
Date: Mon, 15 Dec 2003 13:27:36 +1000
X-Message-Number: 8
http://www.tech-software.net/vk3my.bmp
Andrew Rich (VK4TEC)
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Subject: APRS Gateway
From: "Chuck Mills" <w3yni@comcast.net>
Date: Sun, 14 Dec 2003 22:38:59 -0500
X-Message-Number: 9
Hi all,
Been doing some web based research on this with not much luck. There
seems to be a big "hole" in my part of the state for stations to receive
APRS packets thus all of these folks in the vehicles sending out a burst
every minute are sending them to nowhere. I have an opportunity to bring at
least one, possibly two sites up if we get enough equipment but need help on
where to start. I have the radio, a tnc, computer and decent simplex
coverage. Any help would be greatly appreciated.
Thanks,
Chuck
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Subject: Re: Strange Forecast
From: Gerry Creager N5JXS <gerry.creager@tamu.edu>
Date: Sun, 14 Dec 2003 21:43:11 -0600
X-Message-Number: 10
Think in terms of the combination of effects of an air mass marching
toward an area of low pressure. Let's discuss, for the nonce, the
concept that a low pressure region is also a depression toward the
Earth's surface, and a region of high pressure will form a dome. This
is great in a steady-state condition, but when you add a little
dynamics, things change.
The region of air leaving the zonal high pressure region pushes out as a
wavefront, rather than a streamline, as it's often depicted. The high
pressure air has more mass, generally, than that of the low pressure
region it's trying to go toward, and more energy. It's warmer. It's
inclined to heat up the cooler, damper air of the low pressure region.
Warm, high pressure air acting as a wavefront, reaches the area of lower
pressure air and pushes itself into it.
Another approach to the same explanation: A gravity wave is an
oscillation caused by the displacement of an air parcel which is
restored to its initial position by gravity. The lifting force is
buoyancy, while the restoring force is gravity.
One thing often ignored in the simple view of atmospheric science is the
suggestion that air is not acted upon by gravity. "Ye canno' change th'
laws o' physics, Captain!" to quote an old, future Chief Engineer.
If this still appears gobbledegook, Let me know and I'll take another hack
at it, or turn one of my grad students loose on a simple explanation. He
could probably use the exercise!
The phenomenon is frequently observed: The wake of a boat, the ordered
lines of puffy cumulus clouds, are both straightforward examples. These
waves transfer momentum and energy from the troposphere to the mid-levels
of the atmosphere where they interact with the weather systems we are used
to experiencing. What's happening is that the atmospheric scientists are
gettimg more comfortable with some of the physics that drives these things.
Gerry
--
Gerry Creager -- gerry.creager@tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Page: 979.228.0173
Office: 903A Eller Bldg, TAMU, College Station, TX 77843
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END OF DIGEST
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