[layman]order of colors in rainbow?

Okay, we get a rainbow. I understand pretty much what's going on there.
What causes the colors to be in the same order every time?

Anyone?

Greg Copeland wrote:

Okay, we get a rainbow. I understand pretty much what's going on there.

Apparently not.

What causes the colors to be in the same order every time?

Why do you think they ought to be able to be different?

Mark L. Fergerson

On Thu, 15 Jul 2004 22:14:19 +0000, Gordon wrote:

On Thu, 15 Jul 2004 11:38:20 -0500, Greg Copeland
wrote:

Okay, we get a rainbow. I understand pretty much what's going on there.
What causes the colors to be in the same order every time?

Anyone?
Their wavelengths determine the angle of refraction as they pass
through the air/water surface of rain drops. Red, being the
longest wavelength of the visible spectrum, and violet the
shortest, causes the image to be arranged ROYGBIV. That is Red,
Orange, Yellow, Blue, Indigo and Violet.

That's nearly, exactly what I told someone, but wasn't 100% sure after I
said it. Been a long time since I cracked a book on the topic. Thanks!

There was a fantastic article on this in Scientific American a while back.
Based on the particle size and refractive index, one can get either forward
rainbows or backward rainbows, ROYGBIV or VIBGYOR. Apparently there are
occasionally backwards rainbows from rain also, but I haven't seen one yet
that I recall.

Michael
"Greg Copeland" wrote in message
news
On Thu, 15 Jul 2004 22:14:19 +0000, Gordon wrote:

On Thu, 15 Jul 2004 11:38:20 -0500, Greg Copeland
wrote:

Okay, we get a rainbow. I understand pretty much what's going on there.
What causes the colors to be in the same order every time?

Anyone?
Their wavelengths determine the angle of refraction as they pass
through the air/water surface of rain drops. Red, being the
longest wavelength of the visible spectrum, and violet the
shortest, causes the image to be arranged ROYGBIV. That is Red,
Orange, Yellow, Blue, Indigo and Violet.

That's nearly, exactly what I told someone, but wasn't 100% sure after I
said it. Been a long time since I cracked a book on the topic. Thanks!

"Herman Family" /without_any_s/ wrote in message
news
There was a fantastic article on this in Scientific American a while back.
Based on the particle size and refractive index, one can get either
forward
rainbows or backward rainbows, ROYGBIV or VIBGYOR. Apparently there are
occasionally backwards rainbows from rain also, but I haven't seen one yet
that I recall.

snip repost

Re-read the article. Particle size is almost irrelevant. What *does* count
is the number of internal reflections with the water droplet, which (along
with the wavelength) determines the final angle at which the light emerges
from the droplet. Differences in the refractive index of water for
different wavelengths is called "dispersion" and is responsible for the
*separation* of the wavelengths.

Since 'rainbows' are *always* made with distilled water (it doesn't rain oil
on this planet) the refractive index is not significantly variable from one
droplet to another.

Also, the 'color' indigo was included to please a royal patron, since indigo
is the name for 'royal purple' - a shade of blue-violet - and nourished the
ego of a king with a dream of a divine mandate.

Most serious investigators ignore 'indigo' in the rainbow as it is a
poorly-defined hue.


Tom Davidson
Richmond, VA

"tadchem" schreef in bericht
...

"Herman Family" /without_any_s/ wrote in message
news
There was a fantastic article on this in Scientific American a while
back.
Based on the particle size and refractive index, one can get either
forward
rainbows or backward rainbows, ROYGBIV or VIBGYOR. Apparently there
are
occasionally backwards rainbows from rain also, but I haven't seen one
yet
that I recall.

snip repost

Re-read the article. Particle size is almost irrelevant. What *does* count
is the number of internal reflections with the water droplet, which (along
with the wavelength) determines the final angle at which the light emerges
from the droplet. Differences in the refractive index of water for
different wavelengths is called "dispersion" and is responsible for the
*separation* of the wavelengths.

Since 'rainbows' are *always* made with distilled water (it doesn't rain
oil
on this planet) the refractive index is not significantly variable from
one
droplet to another.

Also, the 'color' indigo was included to please a royal patron, since
indigo
is the name for 'royal purple' - a shade of blue-violet - and nourished
the
ego of a king with a dream of a divine mandate.

Most serious investigators ignore 'indigo' in the rainbow as it is a
poorly-defined hue.


How are the others better defined? I've wondered about that.

jos

"Gordon" wrote in message
...
On Thu, 15 Jul 2004 22:43:32 GMT, "Herman Family"
/without_any_s/ wrote:

There was a fantastic article on this in Scientific American a while
back.
Based on the particle size and refractive index, one can get either
forward
rainbows or backward rainbows, ROYGBIV or VIBGYOR. Apparently there are
occasionally backwards rainbows from rain also, but I haven't seen one
yet
that I recall.

I've seen one, but it wasn't positioned in the sky opposite the
sun as rainbows usually are. This one formed a circle about the
mid-day sun, overhead. The sun was shining brightly through a
hole in the clouds, but rain was falling from clouds all around
the hole. The rainbow formed a complete circle around the sun,
and its colors were in an inverted order.
____________________

One bright sunny day on Kalamalka Lake near Vernon BC in 1959 we were in our
15' Glenn Swift runabout.

A heavy shower sprang up, we headed for a *very* small bay with overhanging
tree branches under which to tuck until the squall ended.

Moored there, when the shower was practically over, we observed the end of a
rainbow entering the water about five feet to the left of our bow, could
have reached out and touched it.

The other end was also contacting the water surface, about fifty feet away.
The whole thing was practically right overhead.

The colour bands were about a foot wide, quite stunning.

Wish I had a camera.

-bg-
www.thelittlecanadaheadphoneband.ca