rainbows ?

[icebread]

are rainbows all the same size from one end to the other and why are thay the shape thay are?

[vascop]

We've had lots of stuff about rainbows before. Do a search on rainbows using the search box above and you'll find one that answers your question.

[gen2]

Put simply:-
1) They all have the same radius
2) How much of the circle you see depends on the elevation of the sun. The higher the sun, the less you see.

[Francis Asis]

I love rainbows. I think they're a really nice invention.

[ChuckFickens]

Invention??

Who was it that sat down and invented the rainbow then? (and I wonder what we done with all this refracted/reflected light before the rainbow was invented)

[chakka35]

They're certainly not all the same size. You can get a rainbow from a spray of water in your garden. There is a fascinating account of rainbows in Richard Dawkins' book Unweaving the Rainbow.

He explains that no two people can possibly see the same rainbow and that a rainbow that looks as if it's way up the the sky might be very much lower, possible at only rooftop height.

[gen2]

Chakka, whether the rainbow is seen in the spray of a hose, a fountain, a waterfall or a shower of rain, the primary bow will always have a radius of 42 degrees. ie. always the same size.
How much of the arc you see depends on the extent of the water spray, and how much of it is illuminated by the sun (as well as its elevation as stated in my earlier answer).

[icebread]

thank you all for your time.

[Henkle]

But no one explained in simple terms why the bow shape forms.
That's what I was waiting for.

[mibn2cweus]

The rainbow is formed by the reflection and refraction of sunlight within droplets of water in mist or falling rain. The angle at which the colours of the rainbow exit from the water droplets depends on the wavelength of the individual colours and how much they are refracted within the water droplets. Because the angle of reflection/refraction is constant with respect to the source of light (the Sun) and the observer, the rainbow forms an arc (not ark) around the observer opposite to the Sun. The reason you see only a segment of the arc (the rain-bow) rather than a complete circle is that the water droplets of rain or mist are only present in those areas above the ground.

http://www.all-scienc...oad/0/03/Rainbow1.png

http://www.wonderquest.com/rainbow-42-deg.gif

While the angle of the arc of the rainbow with respect to the Sun and the observer remains constant, the apparent size of the rainbow will depend on your perspective, the distance from the observer to the ruler, that is the distance to the rainbow and the background upon which you base your measurement.

With the Sun behind you and a spray bottle of water set to mist, you can create a rainbow you can touch and yet your friend will not see a rainbow unless they are standing next to you with their back also to the Sun.

[chakka35]

gen2, sorry to be a bore but subtending the same arc is not the same thing as having the same size, otherwise all circles would have the same diameter.

[morn]

the rainbow is actually part of a circle. normally we only see part of it - the ground cuts it off. Very occasionally we can see the whole circle - if we are far enough away or high enough up to effectively see it below us, e.g. from a plane or mountain top. there is a german technical, scientific, name for the appearance of a full circular rainbow, but it escapes me