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Visual phenomena

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eggshaped
76229.  Thu Jun 22, 2006 1:36 pm Reply with quote



Known in the weather world as a circumhorizontal arc, this rare sight was caught on film on June 3 as it hung over northern Idaho near the Washington State border (map of Idaho).

The arc isn't a rainbow in the traditional sense—it is caused by light passing through wispy, high-altitude cirrus clouds. The sight occurs only when the sun is very high in the sky (more than 58° above the horizon). What's more, the hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground.

When light enters through a vertical side face of such an ice crystal and leaves from the bottom face, it refracts, or bends, in the same way that light passes through a prism. If a cirrus's crystals are aligned just right, the whole cloud lights up in a spectrum of colors.

This particular arc spanned several hundred square miles of sky and lasted for about an hour, according to the London Daily Mail.

http://news.nationalgeographic.com/news/2006/06/060619-rainbow-fire.html

 
Gray
78981.  Tue Jul 11, 2006 6:41 am Reply with quote

This is terrifically weird. I had a look at it yesterday, and IT'S STILL WORKING TODAY! Read the instructions carefully, and take at least three minutes over the gazing bit...

All the best things are accompanied by such phrases as
Quote:
...no one knows why this happens...

 
samivel
78999.  Tue Jul 11, 2006 8:23 am Reply with quote

I don't get the effect described - maybe I'm too introverted.

 
swot
79037.  Tue Jul 11, 2006 9:28 am Reply with quote

Same here. Nobody talk to me.

 
tetsabb
79061.  Tue Jul 11, 2006 10:31 am Reply with quote

no1 school swot wrote:
Same here. Nobody talk to me.


Yes we do, and we 'listen' to you, too

 
Quaintly Ignorant
79077.  Tue Jul 11, 2006 11:12 am Reply with quote

I think it's one of those things where the goal is to get as many saps to stare at coloured grids for as long as possible while those in the know laugh heartily.... I'm quite suspicious of this type of thing

 
Amie
79078.  Tue Jul 11, 2006 11:13 am Reply with quote

I did it a couple of hours ago and did see the haze.. now it's faded somewhat...

 
swot
79245.  Wed Jul 12, 2006 7:51 am Reply with quote

Quaintly Ignorant wrote:
I think it's one of those things where the goal is to get as many saps to stare at coloured grids for as long as possible while those in the know laugh heartily.... I'm quite suspicious of this type of thing


I like the way you think. That must be why it didn't work for me; I'm too intelligent.

[/denial]

 
falco
309504.  Wed Apr 02, 2008 7:47 pm Reply with quote

http://www.youtube.com/watch?v=4_1uQwe9lNs&feature=related

one of the better illusions i've seen. i know how it works and i still can't convince myself its fake sometimes[/url]

 
Colle
442972.  Fri Nov 21, 2008 10:05 am Reply with quote

Wow, that dragon is awesome.
Something I've always liked is this: Can you spot the dolphins?

Now don't come to me and ask "What dolphins?" XD

 
this.recruit.
575634.  Sun Jun 28, 2009 6:24 am Reply with quote

Haha! The dolphin test! I took that once years and years ago and it said the longer it took to see the dolphins the more corrupted your mind was; needless to say, I couldn't see the dolphins. I found it again last year and still couldn't see them, but, oddly enough, I kind of can now; not for long at all but still...

 
Susannah Dingley
575647.  Sun Jun 28, 2009 7:08 am Reply with quote

Here is a simple visual illusion I made out of MS Paint. You might think the circle of the left has a darker shade of grey than the circle on the right.


In fact, the two circles are the same shade of grey!

This is more obvious the further back you move from the computer screen – the further back you are, the better your eyes can focus on both circles at once and ignore the background colours.

 
this.recruit.
575653.  Sun Jun 28, 2009 7:23 am Reply with quote

Actually, it seemed more apparent that they were the same when I was closer... It might just be the lighting, I suppose.

 

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