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The Ground Effect , Pressure Waves and surfing pelicans

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TCups
#1
Dec11-10, 11:46 AM
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The weather is cold and overcast and I am a stay behind in our 12th floor rental on the beach this afternoon while the wife and sister are shopping the outlet malls. I made a new (to me) observation from the balcony: pelicans not only use the ground effect to skim over the surface of the water, they use high pressure air waves created by mechanical waves in the surf to "surf" the air above the waves. I had never really noticed this from ground level and had never really paid attention to it before from an appropriate height and angle to see what the birds do. They glide just in front of a rolling wave, (in a high pressure up draft) until the wave crests (and the air becomes turbulent), then they flap and fly diagonally outward to the next roller, then they glide, etc. etc. So, they not only use the passive aerodynamic advantage of ground effect, they also use the active effect of air pressure waves above the ocean's waves to their advantage.









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Danger
#2
Dec11-10, 12:08 PM
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Neat! I can't say as I've ever heard of that before. There are no bodies of water around here that are large enough to produce waves like that, so thanks for providing pictures.
K^2
#3
Dec11-10, 01:27 PM
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If I tried that, I'd have an FAA rep at my door asking difficult questions. Life isn't fair.

Studiot
#4
Dec11-10, 01:48 PM
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The Ground Effect , Pressure Waves and surfing pelicans

I like the photos of the birds following the wavetops.

Since waves are the result of vertical motion of the water body (reciprocating, orbital or whatever)

How can you be sure the birds are not just fishing by looking for food brought up with the vertical water movement?

Of course, if you are right in your surmise, then you have a new idea for AvatarII.
K^2
#5
Dec11-10, 02:07 PM
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The way the birds travel suggests that they are using wave's momentum to keep them in the air. They basically "surf" the wave, and then cross it at a sharp angle. That's how you would get as much momentum from the wave as you can while still traveling in desired direction.
M. Bachmeier
#6
Dec18-11, 10:27 AM
P: 184
No fair, the photobucket files are missing
A.T.
#7
Dec19-11, 11:13 AM
P: 4,053
Quote Quote by M. Bachmeier View Post
No fair, the photobucket files are missing
Because the thread is one year old. But if you are interested in this:

What efficient sea birds like albatrosses do is called Dynamic Soaring. They can stay airborne for weeks, without flapping their wings once:
http://en.wikipedia.org/wiki/Dynamic_soaring





But from the descriptions about the pelicans here it could be just riding on an air wave, like this:



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