Mountain Wave Question

[acaTerry]

Hey all,

Anyone out there know what / if the chart symbol for a mountain wave is? I know 'em when I see the signs and I sure as he11 know 'em when I get in them. Just can't find any symbology....been to NOAA, FAA, and other sites.

 

[SPilot]

http://www.paragonair.com/public/docs/AdvCircs/AC00-06A_AvWx/

Sorry, the book/pages doesnt give you the exact symbol for a mountain wave, but it discusses alot about it. Seems that if you see Clear Air Turbulence, you could suspect that it is from a mountain wave. Waves also build up around jet streams and fronts, and even around cumulus clouds if the convection is strong and there is a dominant wind component. I've flown a glider up underneath a cumulus cloud, and then been able to climb up on the side of the cloud just in front of it, soaring on the wave-like updraft created in front. I had to practicly stick the wing into the edge of the cloud to be close enough.

http://uap-www.nrl.navy.mil/dynamics/html/mwforc.html

Still no general symbols on this site, but interesting stuff about them.

http://www.raob.com/RAOB5.htm

These guys have kind of their own way of drawing mountain waves...namely as sinus curves.

[...ten minutes later]:

I've been searching around and reading all google have to offer on it now, and still no symbol.

I've noticed a couple of pages says "avoid flying at the same altitude where the lenticular clouds develop". In my hands-on experience this is not good advice. The lenticular cloud develops on top of the extreme up-and down motion of the air, sort of on the top of the sinus curve. When directly below the cloud, you are between the rising and the descending air, and so extreme turbulence occurs ("rotor"). This turbulence exists pretty much at any altitude below the cloud.

I once descended and approached a lenticular cloud at maybe 15.000 ft (4500m). I came from behind (flying into the wind), and I descended below it. As I came closer (say three miles behind, 1000 ft below), I encountered extreme sink, but the air was smooth. I increased the airspeed to get better L/Dmax (this was in a small 750 lbs glider). Once I came below the cloud, I got extreme wind shears all the time, airspeed indicator going from stall speed (and the little glider falling through the sky, at least thats what it felt like), to the yellow range very rapidly, and I had extreme problems maintaining control. It was the worst fight I've ever had with a glider. I got severely throwed around until I came in front of the cloud again, where the air was smooth, and I could regain all the altitude I lost.
This was during an "extreme altitude challenge" mountain soaring camp that I attended for the first time (on my wet license), and so after this first encounter with the "rotor", I've always tried to stay on the upwind side of the lenticular clouds.

Point is: dont just avoid flying at the same altitude as the big lenticular clouds - avoid flying anywhere near them at all. And dont fly on the leeward side of a mountain.

 

[SPilot]

http://avstop.com/AC/aviationweather/sec8.html

Clear air turbulence includes all turbulence (wind shear induced and mountain wave induced) not caused by convective activity

So the turbulence symbol is really the only thing that will tell you about mountain waves, I guess.

_/\_

 

[midlifeflyer]

I don't know if it appears on the prog charts or not, but if you look here, you'll see the symbol for an area where mountain wave is forecast:

http://aviationweather.noaa.gov/exp/gfax/12dec03/

put your mouse over the MTW row. The symbol demarks an area with a line and circle line sort of like

-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o-o

 

[acaTerry]

Thanks guys. I have not seen, in 21 yrs of flying, a mountain wave symbol on any chart. It looks like I'm at a standoff here.

Fly Safe

Terry

 

[Goose Egg]

I haven't ever seen a mountain wave symbol either, although I have seen the abreviation of "ACSL" in a METAR.

-Goose