Regular readers know I am fascinated by sky phenomena; not just astronomy-related but also optical effects in clouds. A few days ago I was out with The Little Astronomer, and I noticed the clouds looked very odd; fuzzy, not well-defined, and very solidly white with almost no variation. My memory tweaked, and I slapped on a pair of polarizing sunglasses. Sure enough, bang! The edges of the clouds glowed pink and green, luminous, iridescent.
I call these Izod-Lacoste clouds, because I remember the pink shirts with the green alligator on them from when I was in high school. The clouds are a lot prettier:
Imagine my surprise when I found out that the day after I saw those clouds, Astronomy picture of the Day posted a picture of them… and the photographer (August Allen) shot it in Boulder! For all I know, that’s the same cloud I saw.
The explanation for why the clouds do this can be found at the APOD page, or on this German weather site (it’s in English). The wave nature of light is critical to making these colors, so it spurred a fun conversation with TLA about waves and interference (which is why polarizing glasses help; the light that comes off the cloud is highly polarized, so the glasses let that light through and block a lot of the glare from the cloud which otherwise drowns the colors out). Come to think of it, we never finished that talk… so now I have something to show her and talk about when she gets home from school today.
Tip o’ the umbrella hat to BABloggee Kyle Carmichael.
November 26th, 2007 at 2:09 pm
For a second I was expecting KNEEL BEFORE ZOD! pareidolia, but this is much more awesome.
November 26th, 2007 at 2:14 pm
Not a bad translation if indeed it written by a German was.
November 26th, 2007 at 2:22 pm
It’s always exciting seeing the fascination with the sky through the eyes of a child. Last week, my little toddler son just warmed the cockles of my heart when we were walking up the steps to our front door in the evening, and he turned and saw the almost full moon and gazed at it then stood there pointing at it for a moment.
November 26th, 2007 at 2:45 pm
Hats off Phil, I think discussing the natural world is one aspect of parenting that is far, far too often neglected. Your post makes me miss the days when my dad would point to something in the sky, on the ground, in the house, a noise in the car, etc and discuss with me what it was and how it works.
November 26th, 2007 at 3:03 pm
A related cloud type is the nacreous cloud. I took this picture near Estes Park, CO back in 2003.
The shot was taken without a polarizer and the colors were even more vivid to the naked eye.
November 26th, 2007 at 3:04 pm
The URL in my last comment didn’t survive. This is what should have been there:
http://milesde.home.comcast.net/DreamLake/LongsPeakCloudRainbow.jpg
November 26th, 2007 at 3:42 pm
Thanks Phil. Your site has also inspired me to talk about the real world with my 13 month old daughter. I was giving her a bath, and we were playing with foam that stick on the wall when wet. I started of saying “look it’s magic!”, but then corrected myself, and in the same tone said “look it’s physics!”
November 26th, 2007 at 4:02 pm
I remember having a similar conversation with my dad over a puddle with a splash of oil in it at five years old. At 15, when interferance phenomena in thin layers came up, I still had a fairly reasonable explanation as to why that might happen. One of my friends thought it was hilarious, saying most dads would likely say “It’s ‘cos there’s oil in it” rather then “Well, you see, in some circumstances light acts as a wave. Now imagine half of the same wave bouncing at the top and half at the bottom of a surface similar to an even divisor of the waves wavelength..”. I thought it strange that a child would accept the lesser explanation, but then perhaps that’s a good thing.
November 26th, 2007 at 4:27 pm
I remember one day in 1996 when the whole sky was full of nacreous clouds which looked quite like the image above expect the colors were more random and alien like in mother-of-pearl… it was quite a sight. In the next day there was still some remains left. They’re not normal clouds since they’re located in the ozone layer high in the stratosphere and don’t necessarily consist of water. They also destroy ozone.
November 26th, 2007 at 6:19 pm
>”A related cloud type is the nacreous cloud. I took this picture near Estes Park, CO back in 2003.”
Looks more like a lee cloud with iridescence. You generally only see the nacreous clouds near sunrise or sunset.
http://epod.usra.edu/archive/images/lenticular_2076_photosig.jpg
November 26th, 2007 at 6:22 pm
> The Centipedeon 26 Nov 2007 at 2:09 pm
> For a second I was expecting KNEEL BEFORE ZOD! pareidolia, but this
> is much more awesome.
I was going to simply post “Kneel before iZod”, but you beat me to the joke.
November 26th, 2007 at 6:26 pm
My first word was ‘Moon’, so I trained my first son to say that word first, too. My second son’s first word was star. I’ve explained stuff like thin-film interference to my eldest (now almost 4) and he knows the names of all the planets (and can identify from Venus to Neptune — Mercury and Pluto are a little more difficult to simplify than ‘the red one’, ‘the one with the rings’, etc), knows that the Sun is a big ball of gas, etc. I showed my youngest the picture at http://www.astronomy.com/asy/default.aspx?c=a&id=6192 and he said “it’s a rainbow moon!” Aaah.
November 26th, 2007 at 6:56 pm
When I saw this on apod, I saw it had been taken over Boulder, and wondered if maybe you’d taken the photo. So many times, you’ll discuss something on your site and that night, when the apod feed updates, there will be the same thing. Good on you, BTW!
November 26th, 2007 at 7:06 pm
Phil et al:
I still try to explain stuff to -MY- “Little Astronomer” :
http://www.cvilleastro.org/casimage.php?image=02-vick-email.jpg
But now that she’s 13 she quickly replies “I know.” to shut me up long before I’ve finished with the explanation. She does this even when she clearly DOESN’T know. It could happen with Zoe someday, and if it does don’t take it personally. It’s just part of being a teenager I think…
So I have to content myself with explaining things to her little sister (11YO). Someday even she will tire of hearing cool stuff from old dad. Then I’ll have to content myself with working with local girl scouts at public outreach events. I’ve helped a goodly number of them get their “Sky Search” badges.
Neat phenomenon! I’ll have to keep my polarizing camera filter handy!
Rich
November 26th, 2007 at 8:52 pm
>>â€A related cloud type is the nacreous cloud. I took this picture near Estes Park, CO back in 2003.â€
>”Looks more like a lee cloud with iridescence. You generally only see the nacreous clouds near sunrise or sunset.
That sounds plausible. The shot was taken in the early afternoon and there can be some pretty fierce winds above the peak.
I guess it’s a good thing that I’m a programmer instead of a meteorologist!
November 26th, 2007 at 10:01 pm
I check out APOD everyday and i saw that the pic was taken in Boulder,Colorado and was thinkin The Bad Astronomer lives there…Cool thing tat you saw this phenomenon…
November 27th, 2007 at 12:21 am
>”That sounds plausible. The shot was taken in the early afternoon and there can be some pretty fierce winds above the peak.”
I wish you had a later shot. I’ll bet it went lenticular. Looks like it was starting to.
November 27th, 2007 at 5:52 am
All I see is an angel.
November 27th, 2007 at 7:24 am
I think I should buy some polarizing sunglasses some time in the future.
November 27th, 2007 at 9:27 am
I happened to hit the Mount St. Helen’s Volcano cam at just the right instant and got this:
http://blog.kickin-the-darkness.com/2007/11/dog-and-plume-mount-st-helens-style.html
November 27th, 2007 at 12:09 pm
Yeah, I saw a moon ring last Friday night. Probably another of the coolest yet eeriest phenomena the moon can make.
November 27th, 2007 at 2:00 pm
I saw a rainbow in the dark (Dio fan) last week. Full moon and a rainbow. Our exchange student took a picture but I haven’t seen it yet.
November 28th, 2007 at 12:49 pm
I saw this phenomenon frequently before my polarized sunglasses were broken. I wonder if this is a Colorado thing (the frequency, not the phenomenon.)
November 30th, 2007 at 7:48 am
[...] APOD: An Iridescent Cloud Over Colorado Nice diffraction. (via Phil) [...]
December 5th, 2008 at 4:08 pm
[...] here ice crystals in the air abound, providing all sorts of lovely refractive and diffractive and interference effects. It’s one of the best shows on Earth… or above it, and it’s free. All you [...]