[Leica] Re: Regarding Rainbows... (Brian Reid - Adam Bridge)

[rpalmier at depaul.edu (bob palmieri)]

In response to Adam's original post:


      So we were out on a catamaran off Waikiki yesterday and everyone
      started commenting on the gorgeous rainbow over the city -  
except I
      couldn't see it. Then it occurred to me that I was wearing  
polarizing
      clip-on sunglasses and darn if, when I tilted them down, there  
was the
      rainbow. Tilting my head 90 degrees also revealed the rainbow.

      So why are rainbows polarized? I didn't expect this and I don't  
think
      I've ever read that they were.

      Maybe I'm the only guy on the planet not to know this but in the
      meantime I thought I'd share.

      Can anyone explain WHY rainbows are polarized?




Brian wrote:
>>

>
> Because they are made of light that is reflected (from the inside  
> of water droplets). It's also refracted (which is what makes the  
> colors) but if there were no reflection there'd be no light to  
> refract.



Another side of this effect is that you can sometimes view a rainbow  
with sunglasses on that nekked-eye folks won't be able to see, as  
evidenced by this snap, (shot through sunglasses with a digicam):

http://www.pbase.com/bobsworld/image/27809448

In this case the water droplet reflections may have been additionally  
polarized by the plane window; I dunno...

Bob Palmieri