Re: [Phys-L] Why are birds similar to airplanes? and Re: [PHYSHARE] Why do birds congregate on the utility wires near the poles?

["Prof John P. Ertel" <jpe@usna.edu>]

     I'm only an old theoretician but I my quick calculations suggest that the tendency of local albedo stirring the air guarantees that convection is at best a 2nd order effect.
     My money is that the sidewalks & pavement act as planer radiators (to 1st order) up to heights of ~10-15 m.
     In short, I think that a slow spreading IR attracts chilly birds substantially more than rising hot air ---unless we are to believe that their collective goal is to be well positioned for a launch onto established thermals!?

ERTEL SENDS!

+==========+

On Nov 4, 2012, at 17:02, jbellina <inquirybellina@comcast.net> wrote:

This has been on object of study by bird behaviorists.

On Nov 3, 2012, at 9:25 PM, Bernard Cleyet wrote:

> On 2012, Nov 03, , at 15:30, Alexander Ruper wrote:
>
> > > But they are very equally spaced and facing the same direction in general
> > > (probably due to the wind).  But why the very regular spacing, even when
> > > one is missing? Then the space is about doubled.  You big guys wade  in.
> > > I'll
> > > watch and keep my ignorance under wraps for a while.
> > >
> > > Larry Brown
>
> Read at end, tho not necessarily authoritative.
>
> > > In a message dated 11/3/2012 2:18:29 P.M. Central Daylight Time,
> > > geepaw@WOWWAY.COM writes:
> > >
> > > Greetings.
> > > There is less sway in the line the closer one is to  the pole.
> > >
> > > My 2 cents worth
> > >
> > > Dic
>
>
> Gate Keeper's reason.
>
>
> The physics of wires and wind:
>
> http://en.wikipedia.org/wiki/Stockbridge_damper
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> bc
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> http://www.squidoo.com/why-birds-like-to-sit-on-power-lines
>
> Birds that sit on power lines almost always face the direction of oncoming wind. Birds have an easier time taking off and landing facing the wind.
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Joseph J. Bellina, Jr. Ph.D.
Emeritus Professor of Physics
Co-Director
Northern Indiana Science, Mathematics, and Engineering Collaborative
574-276-8294
inquirybellina@comcast.net




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