What causes rare rainbow arcs? - Sixty Symbols

Professor Mike Merrifield discusses semi-rare circumzenithal arcs and even rarer supralateral arcs.
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Astronomy Picture of the Day featuring arcs by Magnus Edback: apod.nasa.gov/...
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Sixty Symbols videos by Brady Haran
Editing and animation in this video by Pete McPartlan
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[@General12th]

Thanks to H.I. episode 121 for pointing me here.

[@brennuvargr4638]

What's H.I.? :)

[@splitscim]

@@brennuvargr4638 Brady's podcast, Hello Internet, with CGP Grey!

[@dandoo111]

Hi Tim.

[@conanichigawa]

This video's vertical! ;)

[@Triantalex]

??

[@quahntasy]

Noone explains as good as Professor Mike. Thanks to Brady for bringing such a nice explanation to us.

[@xyz.ijk.]

@@quantumhelix8668 ... and still somehow makes me *not* feel like an idiot.

[@Triantalex]

false.

[@veggiet2009]

Best animations I've seen so far to demonstrate the process of 'rainbow-like' phenomena

[@MushookieMan]

But the animation is wrong, or at least misleading. The crystals that refract light into your eyes are in a circular array. It only showed refraction through a single crystal, as if it forms the entire sundog, which isn't very enlightening.

[@lare290]

I love how he calls Brady "some guy" right to his face.

[@blackflash9935]

lare290 Well...that is the joke.

[@lare290]

@@blackflash9935 I know, that's what I love about it.

[@bengineer8]

time stamp?

[@ro_yo_mi]

Proof the Prof is a Baller!!

[@nathangreene3]

Also called him a lightweight.

[@rozaepareza]

For anyone interested in these sorts of things "atmospheric optics" is the keyword to google.

[@Defeshh]

Lovely, thanks

[@dielfonelletab8711]

There really needs to be a website or a subreddit where you can ask people what keywords you'd need to google to find something.

[@U014B]

"Halo Sim" sounds like a game where you date Master Chief.

[@0rderofTheWhiteLotus]

You win

[@paulamsden8420]

"Some guy called Brady Haran"? Sounds like Dr. Merrifield isn't giving Brady the respect he deserves :D

[@francoislacombe9071]

There was an article in Sky and Telescope about such halo arcs. One interesting thing in that article was that such halos also exist on Mars, but they look quite different because they are formed by dry ice crystals, which have a very different structure from that of water ice crystals.

[@HermanVonPetri]

These are such fascinating and ephemeral natural works of art. I would like to mention a slight niggle concerning the visual aids. The viewer is actually in the space in the center of the arc and the ice crystals make up the material in the arcs themselves. While individual crystals do shine light at a particular angle relative to the light source, the sheer number of randomly oriented crystals in the atmosphere means that the combined light is diffusely homogeneous. It's an illusion to think that there is some actual well defined projection that exists in any one place in the sky. There is not. You just can't see the light from all the crystals that aren't shining in your direction. And the light you see is just the light coming from crystals that happen to be in the right place so that their orientation makes the proper angle to refract the sun's light directly into your eyes.

[@ln5321]

"Merry Christmas! I got you something!" "Oh, mate, you didn't have to do tha--" "I wrote you an essay!" "What? An essay on what?" "Snowflakes have six-fold symmetry and it was tripping me out." "All right, well I was just gonna give you this $5 gift card I won to a store I don't like, so we'll call it a wash."

[@conanichigawa]

A year later: CGP Grey: "Hexagons are the bestagons!"

[@TheyCallMeNewb]

Spectacular work, arc hunter. The animated renderings were terrific!

[@sixtysymbols]

Thanks. Pete did the animations.

[@MarkTillotson]

Indeed - it'll be Snark hunting next I reckon!

[@hernancoronel]

At 3:40 I disagree with the animation. It should show several crystals randomly oriented with the light exiting in different directions forming a (possibly incomplete) rainbow. Thanks for the video and love the professor explanations. Keep up the excellent content!

[@NGC-7635]

...but it could also be aliens. The aliens want you to THINK it’s just ice crystals, but they haven’t fooled me. *adjusts tin foil hat*

[@Theraot]

Plot twist: there are alients that want you to THINK it's just tin foil.

[@spoonikle]

Alfonso J. Ramos - Exactly! the aliens want us to think tin foil hats don’t work!!

[@oremooremo5075]

But Derek from Veritasium showed that wearing a tinfoil hat makes it easier to spy on you

[@RWBHere]

It's a NASA lie! Tinfoil is FLAT!

[@slappy8941]

@@RWBHere You're just crazy. Everyone knows tinfoil was invented by Sasquatch on Atlantis.

[@jeremiahbaker985]

I've been interested in these for a while, I watch for them. I notice from my location in the midwest they seem to occur less often than I often hear predicted. I suspect they are more prevalent in areas of Europe where they are studied with more rigor. This leads of course to the hypothesis that local weather patterns play a significant role in how often these phenomena can be seen.

[@macronencer]

Brilliant! I remember the first time I was able to show my son a sundog, and I took his photo with it behind him and tried to explain what it was. I think Professor Merrifield would have done a better job, though. I love it that you can get software to help you identify what you've seen! That's fantastic.

[@baluskisworld]

Thank you for helping me to understand the true nature of the universe again and again. Another awesome video

[@MyYTwatcher]

Lucky Brady at the right time at the right spot, fantastic prof Merrifield and breathtaking beauty of the nature in one video. This was so awesome.

[@JustOneAsbesto]

The world (including youtube) needs more Mike Merrifield. Brady? Do it.

[@TetonGemWorks]

that's the reason for the comment section... What does it meeeeeeeeeeeeeeeennnnnnnnnnnnnnnnn??????????

[@BrianBlock]

Professor Merrifield is my favorite presenter on this channel. We all need teachers like him!

[@YitzJacob]

Hey Brady :) (I came here from HI, I've only rarely seen your videos but after the discussion on HI, I was very curious to see your rainbow, never seen anything like it! Also, there are sooooo many interesting videos from your archives that KZbin is suggesting, I guess you earned yourself a few subscriptions. !thanks!)

[@sapiense-science-cerveau]

It is amazing to discover both an interesting optic application, but also that it ends up making those wonderful natural events. It makes them even more magic to contemplate!

[@Esc0bar0ni]

I’m a simple man, I see new Sixty Symbols video with prof. Merrifield, I watch and hit like.

[@sixtysymbols]

That’s all we ask.

[@Robertohamoso]

These videos are great, please do more of them. New discoveries make some videos look dated, gravitational waves is one that comes to mind. You've had 8k views in 3hrs so it's worth it.

[@Grinsekatze113]

Pff and I thought we had rainbows figured out. Instead another rabit hole. Who needs sleep anyway xD

[@EebstertheGreat]

These higher order arcs are usually extremely faint or invisible, so it's not surprising they found new stuff in photos of rings formed by snowblowers.

[@Triantalex]

Humans.

[@juniorballs6025]

Awesome as always. Excellence just doesn't get old, thanks very much!

[@Fingerblasterstudios]

The two intersecting arcs kind of reminds me of the artifacts you get when doing a starfield skybox in a video game with just a cube of faces. EDIT: Specifically with mipmaps on.

[@bambooloop9386]

A thing that always trips me up about the visualization at 3:39. The arc you see from the ground isn’t directly because the hexagon sweeps out an arc the way the graphic suggests (or rather a bunch of hexagons really close together at random orientations). It’s about you looking in different directions and hoping there’s a hexagon perfectly positioned to bend the light from the sun into your eyes. Remember that when you look at another part of the rainbow,you’re looking at entirely different snowflakes.

[@emilioherrera6345]

6:30 "Haran arcs, I prefer to call them"

[@JuiceExMachina]

Discovered by the humble "Arc Hunter" (7:37)

[@fahadmalik4797]

Hey Brady! We need more videos!

[@projektor4]

I´m often keeping a look out on the sky to see what´s going on but the first time i noticed a Circumzenithal Arc was when i was looking down and saw it reflected on the surface of my garden pond.

[@iisjebsb26378]

Can't wait to come in September, (providing I get the grades)

[@Triantalex]

??

[@chinookvalley]

I've been seeing the strangest shaped rainbows here in southern Colorado. Some zig-zag, others bow upwards, others seem to be a straight line that goes out into infinity, multiple overlaid bows, 2-tone bows, ... with all the imposed particulates being added into our atmosphere on a daily basis (solar radiation management) I'm surprised we still have any blue to be seen, or white clouds left at all.

[@beskamir5977]

It's rather incredible how old scientists were able to predict stuff with rather impressive accuracy despite not being able to know for certain. Stuff like Kepler basically predicting molecules, a bunch of early psychologists/neuroscientists pretty accurately predicting various neurological systems/pathways that we're just now beginning to understand, etc.

[@althaz]

I saw the tweet and was like "I hope this turns into a video". Nice.

[@sixtysymbols]

Happy to oblige.

[@ThomasGodart]

OMG it's way more complicated than I thought. Thanks for the full explanation

[@stuartstjohn1291]

I note that no mention is made of the order of the colours in the lower arc. In a normal rainbow the red goes on the outside of the bend and violet on the inside. This 'Haran Arc' has the colours reversed...

[@potkettle]

It's because in a rainbow, the light is reflected off the internal "rear" surface of the raindrop, so you see a mirror image of the colour spectrum. In these ice halos, there is refraction, but no reflection, so you see them the "correct" way round. In a double rainbow, there are two reflections inside the water droplet, so the order of colours is reversed back to regular. That's why in a double rainbow, the red bands are back-to-back.

[@RBuckminsterFuller]

Awesome. If I ever see one I'll definitely think of it as a Haran arc.

[@chaoslab]

Thank you so much professor Mike. You are awesome.

[@RWBHere]

Fascinating, and explained so clearly too. Thanks Brady.🙂

[@mrlegoboy413]

thank you for sharing halosim mister professor!

[@seanehle8323]

I've seen the "Sun Dogs" before, but never the circle connecting them, nor the star of arcs intersecting vertical of the sun. That's so cool. Gosh, there's so much cool stuff in that pic. Do a follow-up episode on all the "extra" arcs in the pic, please!!!

[@fatemeh2560]

This was wonderful, very well explained, thank you

[@N.I.R.A.T.I.A.S.]

I wish I'd had just one science teacher as good as Professor Merrifield when I'd been at school.

[@topofsm]

I can't nitpick the optics, but ice doesn't have a hexagonal structure just because it's the most efficient way to pack molecules. If that were true, then solid ice would be denser than liquid water, which isn't the case. Ice has hexagonal structure due to the nature of hydrogen bonding, which will cause H20 molecules to orient relative to each other in a relatively hexagonal pattern.

[@johnmurrell3175]

A lot of the rare arcs were identified by the early polar explorers hence one of them is called the Parry Arc. The cold clear conditions in Antarctica result in fairly frequent displays of the common and rare arcs.

[@iwillfreezeyou]

Video has been up for 2 min and you can already see the likes

[@lobo80085]

Why does the light only show in that specific spot in the sky? At 3:40 why does the light only appear at the end of the beam, rather than showing the entire beam of light?

[@Sirenhound]

3:39 Isn't that backwards? The observer is fixed, you should move the hexagon.

[@philp4684]

@Orange Top The animation is somewhat misleading - It shows light from the sun being refracted through an ice crystal, then beamed out into an arc around the crystal, which the observer then sees. That's wrong. The reality is that the refracted beam leaving the ice crystal either directly enters the observer's eye, or it misses the observer's eye. The light appears as an arc to the observer because only an arc of crystals are in the right positions to refract the light towards the observer. So, a correct animation should show a whole bunch of crystals in an arc arrangement refracting light towards the observer. And maybe other crystals outside the arc refracting light in directions other than towards the observer. More briefly: The arc shouldn't be drawn *around* a single crystal; there should be crystals *on* the arc.

[@waldorf2007]

Best Weatherman eva!

[@tomasthemas]

Ok, this is super cool, BUT, I was under the impression that the rainbow shape emanated directly from the crystals themselves... they had to be in that spacial location relative to you. The animation makes it appear that the crystals are essentially a point-source, and that the rainbow is another reflection that bounces the array of colors to your eyes. Can someone please help me understand this?

[@davidonfim2381]

I may have missed this, but why do the crystals tend to align themselves? I can't think of any mechanism that would do this, and I would think that even the slightest air current would completely randomize the directions of the crystals

[@AstroMikeMerri]

David Enrique you do need fairly still conditions in the cloud so as not to randomise the orientations, but if so they then settle in the horizontal arrangements because it is the most stable, much like a leaf dies when falling from a tree.

[@davidonfim2381]

@@AstroMikeMerri Oooohhh, it's them falling through the air that does it! That makes total sense now. Thanks!

[@janice8500]

And that is exactly why I love this channel!!!

[@collinscody57]

Must be nice to have a team of professors to awnser your random questions

[@3snoW_]

Never knew about Haran arcs ! Nice!

[@brokentombot]

Human: Wow! Angels are in the sky sending us a sign from Jeebus! Physicist: Hold me pint, let me get my powerpoint slide out and I'll explain...

[@abhavishwakarma5035]

This always amazes me, how subtle changes in a microscopic scale can cause such a beautiful scene.

[@gowri1991]

My man Mike is finally back

[@benoitlafleur1364]

Two weeks ago, I was amazed by strange rainbows on both sides of the sun at sunset. Now, I undesstand what these "sun dogs" (parhelion) are made of. Nice.

[@z-beeblebrox]

1:03 did Terry Gilliam secretly animate this?

[@TheAmethyz]

few weeks ago in Finland winter time we saw straight rainbow (rainstick???) and it had also bright normal sun light looking orb so almost like light orb that shoots rainbow laser. it was around 45 degrees in the sky if i remember correctly.

[@ThePrimevalVoid]

Amazing video, as always. Also, Brady, what's up with your microphone?

[@bernhardmelitamann6512]

the funny thing is that rainbows are not two dimensional. When you move closer you still see the rainbow and when you sit down you see it and when you jump you still see it. This means the rainbow is a 3d dimensional volume effect.

[@daniyaradashev1813]

Long live prefessor Merrifield!

[@Terminalss]

I've seen clouds that dont form rainbow like arcs rather the cloud itself is lit up in rainbow colours like an oil spill. No idea how that happens

[@potkettle]

That's iridescence, and is caused in a very similar way to oil on water. The droplets cause a mass diffraction grating, so you get the various wavelengths of light going in and out of phase with each other as the angle to the sun changes.

[@Defeshh]

Great animations!

[@sixtysymbols]

Cheers. They were by Pete.

[@michaelsheffield6852]

Fascinating

[@jackielinde7568]

Are the different (or more exotic) crystalline shapes of ice linked with the different types of water ice?

[@jb76489]

Not naturally, you need very high pressures for those

[@savvapouroullis7927]

a sixty symbols video? Made my month :D

[@ysakhno]

How come a professional camera operator (!) shoots vertical video on his bloody iPhone?

[@sixtysymbols]

Was shooting it for social media. The KZbin video was an afterthought. And I actually like how it integrates. In the modern video grammar it almost feels like “and here’s a moment from the real world”. I think the days of that mattering are over TBH.

[@mokovec]

Why do the two arcs appear to touch? Seems very peculiar how everything aligns so well also on the pic of the day.

[@MarkTillotson]

Its the same geometry of 90% face angles if you think about it, just the crystal's flipped over.

[@litigioussociety4249]

I know sun dogs, solar halos, and lunar halos are caused by similar effects, but I'm curious as to what the difference is that causes a full ring versus a couple arcs or sun dogs?

[@datajunkie190]

Remarkable! Thank you.

[@Gaspode_]

If "the Haran Arc" doesn't take off you could always use "the Parker Sphere"

[@cbrackin531]

hey I have a random video idea. Did we discover math or invent in. Of course we invented the symbols we use( numbers/ letters), but the relationships between the ideas behind the symbols did we discovered?

[@sniffy6999999]

That was explained really well. and I still don't understand it.

[@bhatkrishnakishor]

Rainbows, when God's build kaleidoscope to project some color onto sky.

[@ericpuse5151]

Love the Simpsons/Stephen Hawking reference Brady

[@jordandeck2477]

15/10 video. Wow!

[@bob2nifty]

nice vid thanks

[@josephtixier2404]

Haran Arcs "I don't think you get to call them after you" Professor Mike Merrifield (2019)... Have you looked at the internet lately?

[@altejoh]

I need a new daytime TV show called "Arc Hunter".

[@DANGJOS]

Wow that was fascinating!!!

[@cgaccount3669]

Seems like a square and cube would be just as efficient for packing things as a hex. And less complex.

[@mistag3860]

I saw a moonbow once - quite beautiful and rare - whats that all about then?

[@Camboo10]

To think that double rainbows used to impress the internet. Now look how many rainbows we have!

[@शिवप्रमति]

WOW!

[@davidwilkie9551]

Wow! type pictures, ..and does all this type of explanation tie into X-ray crystallography too, (which I also find difficult, ..to relate the crystal object geometry to the projected interference objectives that is actually to do with entanglement and QM-Time projection, and sync-condensation drawing, Principle of e-Pi-i perspective resonances).

[@MarkTillotson]

Alas, not quite, X-ray diffraction patterns are different from these refraction effects, but all patterns expose the symmetries of the object generating them. Diffraction effects act rather like reflections from layers of atoms, but only when the wavelength is in precise relation to the spacing of the layers. The ice crystal faces are causing the refraction effects, and the faces are also layers of atoms, but only some kinds of layer become faces. X-ray diffraction happens with any layers of atoms inside the crystal (an infinity of such layers exists).

[@ArturdeSousaRocha]

The real question here, though, is why Brady filmed in vertical. :)

[@sixtysymbols]

Was just doing an Instagram story. I always shoot vertical if the primary use is social media. If I’d know it was such a big deal might have got horizontal too, but I think the vertical adds to the excitement and feeling that it’s a “civilian” moment being caught on the fly.

[@Vonwell_]

Double rainbow all the way across the sky!

[@slappy8941]

I saw a quintuple rainbow in 2007 when the sun was setting and the light passed under a rain cloud.

[@aadhithyakota6066]

I came here for the vertical video

[@Triantalex]

??

[@MrWorld-hc5rs]

if you watch it from a helicopter you'd think you're on an alien planet.

[@SparkBerry]

I've been in a chopper trying to chasing a rainbow... It's so trippy!... It's right there but you can never quite reach it!

[@Hogibaer]

...constantly checking if I am on "normal" speed :-)

[@_rlb]

Makes a million excellent videos, still films vertically with his phone :P

[@sixtysymbols]

I was filming that for social media at the time . ;) Filming something horizontally and then posting it to Instagram or Snapchat is equally problematic. I also think there’s something about inserting vertical footage into 16:9 video that says “this was filmed in the real world - out of work hours”. It has a sort of clandestine feel that I like now.

[@cmyanmar13]

But rainbows can be formed by water alone, with no ice? You can make a rainbow with a hosepipe.

[@potkettle]

Yes! An actual rainbow requires a spherical droplet, which ice couldn't form.

[@FlyingJetpack1]

And some people thought double rainbow was impressive, PFFT

[@v0ldy54]

It always bugged me since every rainbow I happen to see is double, why was that guy so shocked by it?

[@Wumbolo]

Did Brady ever ask a bad question?

[@DC-zi6se]

What's around Kepler's neck in the painting.

[@Pedozzi]

Why don't you make a video on moon halos?

[@stevepayne3094]

I stopped the podcast to witness the vertical video.