Re: [Phys-l] Electron vs. Alpha particle...

[brian whatcott <betwys1@sbcglobal.net>]

'Pilots' glories' are seen on the return optical path from sunlight on 
clouds.
An often told anecdote has CTR Wilson engrossed by a glory in mountain fog
at a Scottish Highlands met station returning to Cambridge to invent the 
cloud chamber.

Anthelions are (usually) seen where ice crystals are present.

Maraldi bright spots in the aircraft shadow require good visibility to the
Sunlit ground path.   It's difficult to see these as an airline passenger,
 where the view directly down is obscured.

Brian W

On 1/17/2011 3:14 PM, curtis osterhoudt wrote:
> I'd like to clarify: So far as I know, the Poisson (Arago, Fresnel) bright spot has little-to-no relation with the optical "glory", which is what people are seeing when mountain-climbing or flying.
>
>
> At 14:11 -0600 01/17/2011, brian whatcott wrote:
>
> >   I see the bright spot
> > quite often on the ground when flying under a high Sun.
> It's also pretty easy to reproduce in the classroom. Put a diverging
> lens in front of a laser and put a round-headed map tack (I usually
> support it by sticking it in an art gum eraser) between the lens and
> the wall so that it casts a reasonably large shadow on the wall. Then
> if you turn out the lights, you can see the Poisson spot quite
> easily. It is pretty bright.
>
> Hugh