Jump to content
GreaseSpot Cafe
Sign in to follow this  
sirguessalot

ON RAINBOWS

Recommended Posts

Just some thoughts and questions on rainbows:

The center of a rainbow is exactly opposite the sun (or light that is causing it).

If you could see a rainbow without the earth in the way, it would be a full circle or ring, and your shadow (if there's a surface for it to fall upon) would be inside of the circle, your head being the centermost point. The brightness of the sun would appear as a bright nimbus around the shadow of your head.

A natural rainbow is seen best at dawn and dusk, when the sun is shining most "sideways" through the atmosphere.

I don't think a sun-caused rainbow can be seen at noon.

What causes double rainbows? I'm not sure.

Moving from the outer to inner band, what is the order of colors on both bands of a double rainbow? I wrote it down when I saw one once, but can?t find my notes, and I hear double rainbows are difficult to reproduce. icon_wink.gif;)--> I do remember that the order of colors is reversed on the outer rainbow.

Funny thing is, as beautiful and as sublime as rainbows are, they're not really where we see them. They're not even in or on our eyes. Rainbows only exist in our brain.

No one sees the same rainbow as you do.

And that's kinda cool.

Thoughts?

[This message was edited by sirguessalot on April 03, 2003 at 17:38.]

Share this post


Link to post
Share on other sites

not only do I appreciate the colors...

.....but the trails........and the flashbacks............

Share this post


Link to post
Share on other sites

I remember Craig teaching that the gay supporter rainbows are devilish because they only show 6 colors of the rainbow when it really has a Godly 7 colors.

Isn't one of those colors invisible to the naked eye? I've tried to count them several times and I only see 6 or many more than 7 depending on how they "blend".

Share this post


Link to post
Share on other sites

The color in question is indigo. Standard spectrum colors are red, orange, yellow, green, blue, indigo, violet, indicated by the mnemonic ROY G BIV. It's a dark bluish-purple.

Share this post


Link to post
Share on other sites

I think the colors of a double rainbow are:

(blue sky)

Red

Orange

Yellow

Green

Blue

Purple

(blue sky)

Purple

Blue

Green

Yellow

Orange

Red

(blue sky)

Lindyhopper,

Just curious, were you in the air when you saw the triple?

Or on a mountain or something?

Simpleton,

I've wondered about the 7-vs-6-colors thing too (not cuz of LCM's words. I never even heard that til now). There does seem a puzzle among colorists about how many colors there really are.

A color-wheel has 3 primary colors and 3 secondary colors where the primaries overlap. According to this, the two shades of purple on a rainbow are really just two shades of a single color (for some reason).

But maybe 7 colors make more sense on a double rainbow than a single, because the MID POINT between the TWO rainbows is actually CLEAR, which is really then BLUE sky where the last band of PURPLE unravels and overlaps the blue sky at the middle/inside of the spectrum. Hence, a bluish-purple violet/indigo quandry.

Either that, or my memory is bad and red is the inner-most color, and my whole theory just jumped backwards out its own ***. icon_wink.gif;)--> But even then, red and blue would make purple as well, no?

But I DO at least remember the colors of a double being inverse in order.

Thanks E,

This one's for you:

As dusk and dawn remind us

Of the life and death of our days

The winking sun assures us

Of a secret bridge, gate and way

For while that star lingers

Against quiet ocean and mirror beach,

Hope is never a secret,

And is where every eye can see.

tng

Share this post


Link to post
Share on other sites

One time, when I was on a flight somewhere, I saw a circular rainbow. It was so cool.

And, Zix, if you look 4 posts above yours, you'll see that I already posted about Roy G. Biv.

Share this post


Link to post
Share on other sites

Thank you for posting about Roy G. Biv. First time I ever heard that. I swear you can learn something new everyday. BTW I think its cool how you call yourself Steve! Whenever I see your name it isn't like "oh, its Steve" its like "hey, its STEVE!"

Share this post


Link to post
Share on other sites

rainbows are one of my favorits...you know the pot of gold at the end of the rainbow thing?i always thought they said that cuz you can never get to the end.but my dad insists that when he was young,he stood right inside of a rainbow.(this was before lsd,but my dad is deffintly not normal).this is imposible,no?

[This message was edited by peter on April 04, 2003 at 20:49.]

Share this post


Link to post
Share on other sites

Sir guess, I think the colors of a double rainbow are in the same roy g biv order, not in reverse. I don't think I was on a mountain, as in on top, but I was high in altitude.

Didn't the rainbow in the "men in tights" Athletes of the Spirit prod just add something fabulous to it all.

Wasn't it just thuper?

Beautimous, beutimous!

It don't mean a thing if it ain't got that swing.

Share this post


Link to post
Share on other sites

Lindy,

I think they are reverse.

http://www.doublerainbow.com/

This site has an artist's rendition, in which the violet is on the inside.

But I found that this is the wrong order once I found these other two sites:

Double Rainbow Photo

This one is a photograph, and it appears that the red is on the inside for both rainbows.

Double Rainbow answers

These questions were answered by a meteorologist.

quote:
I have noticed that in rainbows, the color is red on the outside and progresses through the spectrum to violet on the inside. Occasionally, a second larger but weaker bow appears and exhibits a reversal of colors by displaying blue on the outside and red on the inside. Why?

ANSWER:

Rainbows are produced when sunlight is reflected and refracted by raindrops in a manner similar to the refraction occurring when light passes through a prism. The light rays making up the main, or primary, rainbow experience single internal reflection from the back surfaces of the drops. The light composing the secondary bow undergoes two reflections from the raindrops. As you know from looking in a mirror, the action of reflection is to cause an inversion of an image. Your right hand appears to be your left hand. The second reflection in a raindrop reverses the order of the colors in the rainbow. In rare cases, you can see a very weak third bow. It is explained by three reflections and exhibits the same order of colors as does the primary bow. At each reflection, only part of the incident light is actually reflected, therefore, the more the reflections, the less bright the bow.


Then I found this site:

Double Rainbow "cult"

icon_wink.gif;)-->

enjoy

tng

Share this post


Link to post
Share on other sites

ex,

yer too cool.

Ya know, I don't think you can stand inside your own rainbow, cuz it'll run from ya. But you can stand in another's.

Reminds me of that cliche about only being able to feed each other in heaven.

but...

You can only stand in your friend's rainbow.

(sumthin like that.)

...or even: "Hey, you! get yer *** outta my rainbow!"

icon_wink.gif;)-->

goodnight

Share this post


Link to post
Share on other sites

Sir G,

You caught my attention.

You can see a full circle rainbow by riding in an airplane above lots of clouds.

If you can position yourself to look exactly opposite the sun, and if there are clouds when you look in that direction, you'll see the shadow of the airplane on the clouds.

The airplane's shadow will have a full circle rainbow surrounding it. It's beautiful!

Also, a double and triple rainbow happens somewhat the same way several higher pitch harmonics can come off a guitar string.

Share this post


Link to post
Share on other sites

quote:
Also, a double and triple rainbow happens somewhat the same way several higher pitch harmonics can come off a guitar string.

This is wrong. Multiple rainbows occur from multiple reflections and refractions through the atmosphere. Harmonics are in no way involved since the visible portion of the spectrum subtends less than a full octave of frequencies.

Share this post


Link to post
Share on other sites

Zixar,

If you?ve checked into it recently I?ll take your word for it.

You?re probably correct. It's been 35 years since I saw the diagrams and the equations cranked. I think it was second year physics. When you said: ?the visible portion of the spectrum subtends less than a full octave of frequencies? you got my attention most efficiently.

My memory of it, what's left of it and isn't degraded or falsely planted, is this:

White light reflects back and forth within each raindrop. The raindrop?s dimensions are of the order of the light?s wavelengths. Differing harmonics of colors will geometrically gang up with each other and against each other in constructive and destructive interference (sounds like Grease Spot) giving rise to the higher order rainbows. This is admittedly a very crude grasp, but it?s I all I have on this subject.

When I posted, I had a stronger phrase in there that I quickly edited out. I watered down my statement to: ?happens somewhat the same way? and even considered adding the word ?maybe.? I should have.

I put all my rainbow investigations into the ?Finished? folder when I happened to visit Niagara Falls in 1969. I had a fresh memory then of the diagrams and equations, and at the falls I could see many near complete full circle rainbows at times and from certain locations, especially when wind gusted up and the water sprayed in the air more. I?ve not looked at them since, so I?m interested in efficient, neat bundles of summation like your ??the visible portion of the spectrum subtends less than a full octave of frequencies?? statement. It skips around the need for diagrams and equations.

One thing I did retain from rainbow physics is this. It?s easy to predict rainbows.

Zixar, I?m sure you know this, so for the other rainbow lovers out there, it can really easy and fun to predict rainbows. You can also help get someone interested in this beautiful subject?s physics if you say ?I?ll bet there?s a rainbow behind that building!? and sure enough, walking around and WOW! There it is! Then you can explain to your friend how to predict them. Kids can be taught these simple points in prediction, and they can be motivated to pay attention to science from the enjoyment.

**********************************

Here?s how to predict rainbows:

They happen MUCH more likely when the sun is lower in the sky, morning or afternoon. Noon is impossible almost, I think. (maybe, possibly)

As pointed out by sirguessalot, they are in the opposite direction as the sun approximately. The center of the rainbow is exactly opposite the sun. Let?s call this the ?sun-opposite? region of the sky. This region is also somewhat lower in the sky. Not straight up.

There needs to be water, or mist, or clouds, or gloominess in the ?sun-opposite? region of the sky.

There needs to be strong sun shining, not necessarily on the ground where you are standing, but there needs to be sun shining in the direction of this ?sun-opposite? region.

********************************

So, if you can see that there?s rain on the whole region on the other side of that building, and there's strong sun in the opposite direction as the building, the time invested in a walk around the building is well worth it.

Share this post


Link to post
Share on other sites

Steve!

I'm going to have to dodge that question.

Really, though, I've GOT to go to work! HONEST!

I hope this doesn't reflect poorly upon me!

Share this post


Link to post
Share on other sites

Harmonics are integer multiples of a given frequency. The lowest possible visible frequency (dark red) has a wavelength of about 700 nanometers. When you double the frequency, you halve the wavelength. Thus, the first possible harmonic of that color is at 350nm, which is, unfortunately, fifty nanometers into the invisible ultraviolet potion of the spectrum.

No. Harmonics. Period.

Share this post


Link to post
Share on other sites

I believed you the first time, and could could see it qualitatively. Now, you've repeated it quantitatively.

So, thanks for the numbers. The orders of magnitude of these things are far from my memory, and somewhat far from retrieval in my books. Even the books are far, some of them.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×