Comments on: Aerodynamic and Rainbow Contrails

By: Gli sciachimisti non hanno il senso dell’umorismo « Paoblog

Gli sciachimisti non hanno il senso dell’umorismo « Paoblog — Thu, 22 Jul 2010 06:56:30 +0000

[...] fa è apparso su Youtube un bel video che mostra un aereo in volo mentre rilascia una classica scia di condensazione aerodinamica (una di quelle che si formano per via della variazione di pressione dell’aria mentre scorre [...]

By: faithinscience

faithinscience — Tue, 20 Jul 2010 10:00:11 +0000

That’s the problem I have with these people…They are NEVER held accountable for their claims. He disappears after making that ridiculous statement and probably believes he has “won a debate”.

By: Kamran

Kamran — Tue, 20 Jul 2010 08:44:03 +0000

What specifically is bullshit bio?

And he’ll never be seen again. Or there will be copypasta from conspiracy sites.

By: bio

bio — Tue, 20 Jul 2010 06:23:44 +0000

this article is BULLSHIT

By: JazzRoc

JazzRoc — Sat, 24 Apr 2010 11:08:58 +0000

Archaeopterix:

“The scientific term is refraction”

No. “Interference“.

By: Archeopterix

Archeopterix — Sat, 24 Apr 2010 09:21:36 +0000

Hi again.

I wanted to make a remark about the explanation you used regarding the different colors in relation to the different sizes of ice particles in the above example of aerodynamic contrails.

The scientific term is refraction, or the bending of light to or away from ‘line normal’ which is the normal path the light is traveling in. The higher energy the ray (or particle, in this case photons of light) the more it will bend in reference to the observer when it enters a medium of greater refractive index from a lower one (I.E from air into water or glass). This is why if you stick a pencil in a glass of water it appears ‘broken’ if you look at it edge on; the light is being bent or refracted as it travels from the air into the water.

As for the contrails the same principle that causes the rainbow effect in the different sized ice particles is true of opals: Opals actually do not have a regular repeating crystalline structure like other gems. They’re composed of tiny ‘beads’ or smooth grains of silicates at varying sizes. The larger the grains the longer the wavelengths they refract because essentially the longer wavelengths cannot ‘fit’ inside the smaller grains. The same effect causes you to loose your wireless signal as you pass under an overpass or through a tunnel. The carrier waves literally cannot fit. And so the smaller ice particles are responsible for colors on the shorter end of the spectrum such as blues and greens and the larger ones are responsible for the ones on the longer end such as reds and oranges.

Just thought I would comment. I hope this post is not too irrelevant to topic, or that I insulted anyone’s intelligence ( I know some guys are going to be thinking, yeah, jackass, we know! we know! It was in school!) I just thought the science was fascinating.

By: Uncinus

Uncinus — Thu, 11 Mar 2010 18:48:58 +0000

I guess so But I was just using the term “rainbow” in the sense of the spectrum of colors, not the mechanism of creation.

By: danjferg

danjferg — Thu, 11 Mar 2010 18:26:19 +0000

Quite right, I missed the paper. Mie scattering is new to me. That better explains the repeating bands of color. I always find it interesting how light interacts with virtually the same medium of water in such a myriad of ways. Scattering, refraction, diffraction in so many different flavors. Sometimes it’s hard to imagine how something as simple as the size of the water droplets can make such a big difference in how the light patterns are interpreted by science. Make them really small and you can’t call it a rainbow anymore. I guess that means the article title is wrong.

By: Uncinus

Uncinus — Fri, 12 Feb 2010 22:56:41 +0000

But it’s not a rainbow. Did you read the explanation?

http://contrailscience.com/files/Gierens_Aerodynamic_poster_060625.pdf

By: danjferg

danjferg — Fri, 12 Feb 2010 22:48:28 +0000

The presence or absence of the rainbow colors in the contrail is a result of the angle formed between the viewer, plane and the incident light. The presence of a rainbow is dictated by the way light refracts off of circular water droplets. Most sky rainbows are seen when the sun is low and at your back. In the images above I’d guess that the sun had to be very low in the sky to see a rainbow from directly below the aircraft. Someone call the photographer and very for me?

If you can handle a little physics check out the MIT lecture at http://video.google.com/videoplay?docid=-2978729867097229598&ei=Ddl1S83zH5PorAKF9PjdBw&q=mit+rainbows&hl=en&view=3#