Dear Boyd
What I think they mean is a wave formed in the lee of the mountain range, ie
the air has descended on the lee slopes of the mountain range and then
further downstream rebounded from the valley floor with often a multiple
number of subsequent oscillations. The text you quote from Avweb implies
wave lift (ascending air) on the lee slope which is not the case in classic
"lee wave" conditions.
The book "Meteorology and Flight - A Pilots Guide to Weather" by Tom
Bradbury which primarily is directed at glider pilots gives this empirical
rule for wavelength in miles versus wind speed in the layer where waves are
formed.
Wavelength in miles = 0.17 x (speed in knots) - 1.6
This leads to 30 knots >> 3.5 miles
40 knots >> 5.2 miles
50 knots >> 6.9 miles
60 knots >> 8.6 miles etc.
I only chuck this in to try and give a rough indication of possible
horizontal scale of the phenomena.
(Of course wavelength varies with many factors so you roll out a serious
number crunching computer to get better information in a particular
situation.)
There is a lot of information on lee waves available and you probably have
encountered some basic information in general flying texts on meteorology.
Try googling 'lee waves' or 'atmospheric lee waves' or some such. If
instead you want me to drown you in electronic info send me an email direct.
I can either email a few articles with a gliding bent or go for saturation
via burning a CD for posting you.
Otherwise there are some really knowledgable people out there who do fly
serious and high waves in contrast to those of us who just read about
serious waves but only occasionally fly weaker low level waves. Ric Agnew
at Canberra Gliding Club comes to mind, where of course they have serious
waves accessible from their site.
Cheers
Roger Druce
[EMAIL PROTECTED]
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Boyd Munro
Sent: Friday, 22 April 2005 10:30 PM
To: Discussion of issues relating to Soaring in Australia.
Subject: Re: [Aus-soaring] From Avweb
"The rising wave of air on the downwind side of the ... range"?
I have flown powered aircraft many times North and South along the Sierra
Nevadas and have encountered some very powerful standing waves - but not a
rising wave on the downwind side.
I'm inexperienced in gliders. I have great respect for the accuracy of
Avweb, where I first read this quote.
It would be great if a gliding expert could make sense of this.
Boyd Munro
----- Original Message -----
From: "Leigh Bunting" <[EMAIL PROTECTED]>
To: "Soaring List" <[EMAIL PROTECTED]>
Sent: Friday, April 22, 2005 12:13 PM
Subject: [Aus-soaring] From Avweb
SAILPLANE POSTS NORTH AMERICAN DISTANCE RECORD
A California glider pilot has been quietly working away at breaking the
North American distance record, with a flight of 1,212 miles in 13 hours and
17 minutes on April 3, breaking his own unofficial record of 1,130 miles set
eight days earlier. Gordon Boettger flew a 33-year-old Kestrel 17 sailplane
along the rising wave of air on the downwind side of the Sierra Nevada
mountain range during a lee-wave storm. He reached heights of 27,000 feet,
and the canopy of the plane was sometimes covered in ice. Boettger, 37,
soloed in a glider at age 14, flew off aircraft carriers during eight years
in the Navy and now flies MD-11s for Federal Express.
--
Leigh Bunting
Colonel Light Gardens
South Australia
<Open Windows and let the bugs in>
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