Sunday, February 03, 2008

Rainbows are awesome!

I just have to share these pics I took this evening.

These are completely unaltered pics.

The unreal thing about this rainbow was that it stayed there for almost an hour. I've never seen that before. Is that common? And, P2 had a question that I couldn't answer...and, since I know I have the coolest and smartest readers on the planet, I'll throw the question your way: Why are the colors in a rainbow in the order that they are? And, secondary question: Is there any circumstance where they would be in a different order? And, the third part: Does temperature effect the rainbow?

I had to use the old, "I don't know." answer for two of those and I'm not entirely sure my answer for the one question is completely accurate. So, school us! :) Please.


Chris said...

Without looking anything up, I believe the colors are that order because of the light wavelengths. The water droplets act as a prism, separating them from shortest to longest (or the other way).

Since that's the way the light separates, I don't see how they could be in different orders. Maybe if it appears upside down the colors would seem reversed?

Anybody who knows any of that science thingamajiggy feel free to correct me, though

Panhandle Faithless said...

Yeah. It's due to the wavelength. And, no, they can't appear in a reversed order. Sometimes there's a double-rainbow, with the outer rainbow having the colors in the opposite order. Shorter wavelength light is refracted through a larger angle, which is why it is further inside.

I might have messed this up, but there's always Wikipedia!

Milo Johnson said...

Think of a piano keyboard. Each hue has its own note, always the same note for the same color, and fixed in relative position to each other as determined by the vibrations per second of the string. And no, hour-long rainbows are not terribly common, but when there is enough moisture in the atmosphere and the angle of the Sun is high enough, they do happen.

James said...

As light traveling through the air hits a water droplet, it slows down a bit. This slowdown causes the light beam to bend. (Imagine driving from grass into mud at an angle. The tire that hits the mud first will slow down relative to all the other tires, causing the car to turn toward the mud.)

Regular white light is composed of all the colors you see in the rainbow, and different colors are different wavelengths of light. These different wavelengths all slow down at different rates when the light passes from air to water, and so they all bend at different angles. When the light exits the water droplet back into air, they bend a little bit more, and the light is separated into a rainbow, which really means the light is sorted from long to short wavelengths.

There are also some lens effects that can happen, but the primary reason the light is sorted that way is due to speed changes when it moves between materials.


James said...

Also, that's pretty much how a prism works.

toomanytribbles said...

there's lots of stuff about rainbows here:

Anonymous said...

Nice photos. It's great that you got to enjoy it for such a long time. One of life's precious moments, which, fortunately for you, was nicely extended beyond the usual duration.

Anonymous said...

Violet has the most energy, and gets bent the least by the prism effect. The rest of the sequence has less energy in order, with red being the lowest energy level of the visible spectrum, thus why it is bent the most.

The reason it only appears with violet at the bottom is that it's a lensing effect with the curvature of the atmosphere, with the most direct line along the inner curve.

Of course, if we could see infrared and ultraviolet, it would extend further both ways.

Berlzebub said...

Since most others have explained how the light bends and separates, I won't bother with that.

However, you've just given me a blog post idea, P-Momma. :-D

Brent Rasmussen said...

This reminded me of an old post of mine from 2003: "Destroyer Of Magic Rainbows".

Riker said...

I didn't see anyone address the temperature question yet, so I'll field that one:

Since the rainbow is entirely dependent upon the presence of water droplets in the air, temperature will affect it, but only to the extent that temperature can influence the air's ability to contain moisture.

Warmer air can hold more moisture than cold air, which is how we get rain in the first place... warm, humid air cools down, which squeezes water out of it, creating rain.

So, if the air suddenly warms up, condensed water droplets will be reabsorbed into it and the rainbow will disappear.

boo said...

As others have said, the colors of the rainbow are in the order of the wavelengths of the light. Here's an old mnemonic to help remember the order of the colors in the spectrum:
ROY G. BIV -- Red, Orange, Yellow, Green, Indigo, Violent

Chris said...

Y'all are all wrong! It's God promising not to flood us again. Now stop it with the science babble, trying to undermine His glory with earthly knowledge, and pray.


Milo Johnson said...


Jim said...

Wikipedia also has a pretty good article on rainbow physics. My favorite fact is that you can't see a rainbow unless the sun is less than 42 degrees above the horizon; the exception to this being if you are on a mountaintop or in an airplane.