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Author Topic: Why are rainbows curved?  (Read 2984 times)

Offline chris

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Why are rainbows curved?
« on: 16/01/2008 23:27:40 »
What governs the shape of a rainbow? Is it actually circular if you look at it from the correct position?

Chris


 

Offline JimBob

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Why are rainbows curved?
« Reply #1 on: 16/01/2008 23:43:52 »
I do believe it is the combination of the many roundish rain drops through which the light is refracted into the different colors, the position of the sun and the curvature of the earth. Together, the rays of the sun get bent into a curve. 

A more accurate scientific explanation will be forthcoming I am sure but, what the heck, I can try can't I?
 

Offline Karen W.

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Why are rainbows curved?
« Reply #2 on: 16/01/2008 23:55:18 »
Having to do with light bending eh? I think!
 

lyner

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Why are rainbows curved?
« Reply #3 on: 17/01/2008 00:04:59 »
A rainbow is always circular (or a part of a circle). This is because the light is reflected internally on the inside of spherical water droplets. Because of dispersion, the various colours (wavelengths) are refracted (bent)  a bit differently as they enter and leave the drops. The light comes from the Sun and, any ray that enters your eye  will always have been  bent by the same amount (i.e. the same angle).  Remember, the Sun is behind you and the bow will be in front of you. The symmetry of the situation means that there will be a cone of light (constant angle) of each  particular wavelength  entering your eye so you will see a circle.

Have a look at this:
http://eo.ucar.edu/rainbows/
« Last Edit: 17/01/2008 00:10:12 by sophiecentaur »
 

paul.fr

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Why are rainbows curved?
« Reply #4 on: 17/01/2008 02:39:33 »
"Is it actually circular if you look at it from the correct position?"

A 22 degree rainbow, or halo, will be a complete, visable, full circle viewed from the ground. The colours will be less spectacular...but you do get the full circle.
 

Offline RD

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Why are rainbows curved?
« Reply #5 on: 17/01/2008 15:31:30 »
Complete rainbow circles are visible from aircraft ...
http://www.atoptics.co.uk/droplets/gloim21.htm
Or mountain tops ...
http://www.atoptics.co.uk/droplets/gloim20.htm
« Last Edit: 17/01/2008 15:34:04 by RD »
 

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Why are rainbows curved?
« Reply #5 on: 17/01/2008 15:31:30 »

 

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