http://www.chgpa.org/forums/viewtopic.php?f=2&t=6518&start=38

Matt writes:

Once in the air, lift was abundant and I enjoyed playing in smooth
climbs to 4000'msl up and down the ridge. The views were spectacular as always
at this awesome site and the flying was a pure joy. After a couple hours of
bobbing around up and down the ridge, I decided to fly out into the valley and
try to tag the water tower in Woodstock before landing.

As I made my way out into the valley, I was surprised to find that I was
steadily climbing in broken lift as I flew toward town. I was surprised to find
this light, but consistent, lift line in December. I continued to fly straight
into a 14 mph headwind at 24 mph, relaxed and enjoying the views with one arm
draped over the bar.

At around 4000' the air got ratty and I was getting tossed around, but still
climbing. In an instant at around 4500', I was in as smooth of air as I have
ever flown and my vario was singing as I watched 400-700fpm climbs (blips of
900fpm) register. I was in wave!

I had heard and read about it, but never experienced this awesome phenomenon.
There were no clouds in my vicinity, but out in front of me at the other side of
the valley, there was a beautiful thin white mat of clouds that stretched off
into the distance. As I flew toward them, it felt surreal to fly above cloudbase
and then above the top of the clouds, looking down at a uniform white carpet
that covered the ground into the distance; all while flying straight out into
the valley on this unexpectedly beautiful December day.

At just under 7000', I flew out the back side of the wave and my smooth
ascension above the clouds was replaced by 1100fpm sink and I was parachuting
back to earth. I turned 45 degrees to escape the sink and then 90, but was still
seeing sustained 6-900 down. The rate of decent was so significant, for a
second, I thought I might not make it back to the primary LZ and would be
landing out. With a 15 mph tailwind, I was quickly back to the bridge field
where other pilots had landed.

Bacil responds:

Having studied intensely and flown in wave I can offer some
insights. When Matt flew thru the chop, that was the rotor beneath the wave
crest. The rotor is modeled as a circular "tumbleweed" rotating in place under
the wave crest. The crest of the wave was probably above 10K' MSL. I took a
picture of a wave cloud from the LZ and it was quite high and was more
cirrocumulus than cumulus; hence the height guess of 10K' MSL+.

As Matt flew thru it he then hit the front side of the wave, which he aptly
described as butter smooth 400' up. To exploit the wave lift you slow down to
where your ground speed is minimal to zero so that you stay within the confines
of the wave lift. You can also fly laterally left and right and "surf" the wave.
You could fly off of the end of the wave if you fly far enough laterally. Or you
could just slow down and ride the "escalator" to the top floor.

The wave can be stationary, or it could shift upwind or downwind. The point is
to explore the wave boundaries. However, a word of warning. Flying in wave is a
serious endeavor and not to be taken lightly. As you ascend in wave the headwind
increases, and can increase to a point where you cannot make forward progress.
Wave lift can also take you to heights that can produce frostbite and
hypothermia if you are not adequately prepared for the colder temps. And if you
don't fly far enough downwind of the wave, the turbulence from the rotor can
make your flight a bit rough to really bad.

Matt punched off the front of the wave and encountered greater than 1000'/min
down, which got him down from altitude w/o turbulence. That was a wise move
rather than run downwind and possibly thru the rotor I just described that
exists below the crest and behind it for some distance.