Sunday, August 02, 2015

Wings. Wings. My kingdom for some wings.

South Burlington, VT

This morning as I sipped my morning coffee at the Burlington Airport, two spectacular lenticular clouds formed over Mount Mansfield as I watched. (pic below)   It made my heart ache because that is the visible signal for the most glorious of all soaring conditions.  I want to be up there flying right now.



Some background.  Vertical wind shear refers to the case when winds blow faster as you go higher.   When that happens, and when the wind blows over a mountain, it creates a "mountain wave." The lenticular (i.e. lens shaped) clouds mark the crest of this wave.
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The good part is that downwind from the mountain, about 5 miles away, an invisible secondary wave will form.   Gliders in that wave are lifted up as if in a rapid elevator.   The higher they go, the faster the wind.  That continues until airspeed matches wind speed and the glider becomes stationary with respect to the ground.  I achieved that once in the 90s.  It was on the east side of Mount Mansfield, about 14,000 feet up.   I could see all of Vermont, and much of New Hampshire and New York.  I could see across the Adirondacks and Lake Ontario to Toronto.  It made a life-long impression on me that I'll never lose.

In the Sierra Nevada Mountains, the waves are enormous.  Soaring pilots there hope to someday achieve a new word record altitude for a glider at 75,000 feet.

That is why today's sight makes me salivate and wish that I was up there.  But I had to give up flying long ago because it was far too expensive a hobby.

If you have trouble imagining the mountain wave, the diagram below explains it.





I prefer the water analogy such as that bear is looking at. The same thing happens when swift water flows over rocks, but the scale is different.




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