Interesting Day... Wave effect or what?

[solo6796]

We were going to have a contest between Austin, San Antonio and Houston at the Houston Hawks Field today, but the forecast was for high winds, and we rescheduled.

A few Hawks members still wanted to try it out. Up until noon, the wind was 10-20 and gusty, and kind of hard to keep flying smoothly in the high turbulance. After that, Tauno got some lift and I decided to try again. After launch, I was heading into the wind, and My SuperV started to pick up speed, and altitude, and like on an elevator, went almost to spec. I brought it back down, and went up a few more times. Several of us did this, It was very cool, and lasted for a couple hours. Whatever it was... I want more!

AJ

[OVSS Boss]

It was wave, wonderful stuff huh....

[LVsoaring]

I thought Texas was mostly flat... at least the little bit of it I've seen. So where did the wave come from?

[solo6796]

There was a cold front moving in from the North and the wind was from the North.. I don't understand the physics, but We REALLY enjoyed the ride!

AJ

[OVSS Boss]

LV, wave can form anywhere. Watch your clouds, you can see formations that show it. David hobby has written about waves that form off Australia that they go out 100 miles plus and never thermal in full size stuff. Probably many causes, but it does not specifically have to be a mountain.

Marc

[LVsoaring]

Interesting info Marc. I always assumed you needed some sort of bump on the earth's surface to get the wave going.... Maybe I was under that impression because the only waves I'm familiar with are the kind over the Sierras and mountains around LV. The lenticular clouds that I've seen indicating wave are always over or downwind of the mountains.

Rick

[schrederman]

Low level waves can be formed by a heavily treed area after a wide field, particularly if there's another field behind for the wave to bonce back up from. Wind speed, width of the treed area, it's orientation to the wind, etc. all have effect on how/if that happens. The first wave will be twice as high as the trees. The secondary will be twice as tall as the first. The tirtiary, if there is one, will be twice as tall as the second.

That's from a micrometeorology text I read a long time ago when I was trying to figure out thermals and so forth... when I was a junior Nordic builder... along about 1964 or so...

Jack

[John Cole]

Or... perhaps a shear?

John

[bobthenuke]

AJ,

Boundry level meteorology is not my forte, but from your description of the current weather at the time you were flying, it sounds like you guys were lucky enough to be in position to take advantage of a "gravity wave". Unlike the more easily understood (at least to me) "mountain wave" with it's tell-tale lenticular cloud and accompaning rotor cloud, a gravity wave is generated by disturbances within the atmosphere, where the forces for the wave motion are provided by buoyancy and gravity. The disturbance source could be frontal lines, density currents, jet streams, convection penetrating a stable layer, squall lines or low level turbulence such as the tree line Jack described.

...bob