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Thread: Rainbows everywhere!

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    Rainbows everywhere!

    We've had an outbreak of rainbow symbolism in the UK, in relation to Covid-19 lockdown. It reminded me to start up a long-delayed project, which was to write myself some code to explore the higher-order rainbows beyond primary and secondary.
    I though I'd post the final result here, in case it's of interest. The diagram is inspired by a Jearl Walker "Amateur Scientist" column in Scientific American, back in 1977, but the calculations and "artistry" are all my own.
    rainbow.jpg
    Of course, you need to mentally rotate the rainbow rosette clockwise to depict the situation when the sun is above the horizon.
    Successive higher-order rainbows get progressively wider and fainter--my depiction of the increasing faintness is entirely diagrammatic. The tertiary rainbow is usually hidden in what's called the "zero-order glow" around the sun--directly transmitted light is much brighter than the rainbow rays. It's been seen by experienced observers on several occasions, and has now been photographed several times. The quaternary rainbow, which sits right next to it, has also been photographed using stacking techniques, and the quinary rainbow, partially hidden within the secondary but protruding into Alexander's Dark Band (between the primary and secondary), has also been photographed (although I find the images I've seen a little unconvincing).
    Beyond that, I'm not aware of any other rainbows that have been identified in the wild. The duodenary (order-12), which actually crosses the sun and forms two superimposed discs of colour, is probably a no-hoper, but it feels like some of the others could yield to the sort of image-processing commonly used by astrophotographers.

    Grant Hutchison

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    Very nice Grant; I've always been interested in such things.

    My go-to site for this, Atmospheric Optics, does have some stuff about 3rd and 4th order, and even 5th and 6th (images on the linked website).
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    Formula 1 car racing restarted last weekend; they too are using rainbow symbolism. They have probably the worst rainbow I've ever seen. It's offensive to my inner Roy G. Biv.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

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    Quote Originally Posted by grant hutchison View Post
    We've had an outbreak of rainbow symbolism in the UK, in relation to Covid-19 lockdown. It reminded me to start up a long-delayed project, which was to write myself some code to explore the higher-order rainbows beyond primary and secondary.
    I though I'd post the final result here, in case it's of interest. The diagram is inspired by a Jearl Walker "Amateur Scientist" column in Scientific American, back in 1977, but the calculations and "artistry" are all my own.
    That's quite nifty. If it's alright with you, I'm of a mind to PDF-ize that and keep it on my phone for quick reference.
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    Quote Originally Posted by Swift View Post
    Very nice Grant; I've always been interested in such things.

    My go-to site for this, Atmospheric Optics, does have some stuff about 3rd and 4th order, and even 5th and 6th (images on the linked website).
    Yes, that's a great resource. It was Les Cowley, of Atmospheric Optics, who coined the phrase "zero-order glow" for the light that comes straight through raindrops without reflection.

    Grant Hutchison

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    Quote Originally Posted by Trebuchet View Post
    Formula 1 car racing restarted last weekend; they too are using rainbow symbolism. They have probably the worst rainbow I've ever seen. It's offensive to my inner Roy G. Biv.
    Also probably the worst typeface I've ever seen. The proportions on that are horrible. Takes me back to mass market SF paperbacks of the 1970s.

    Grant Hutchison

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    Quote Originally Posted by PetersCreek View Post
    That's quite nifty. If it's alright with you, I'm of a mind to PDF-ize that and keep it on my phone for quick reference.
    Feel free.

    Grant Hutchison

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    If anyone's interested, I just posted more illustrations and detail concerning high-order rainbows (tertiary and beyond) here.

    Grant Hutchison

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    Cool
    At night the stars put on a show for free (Carole King)

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    Quote Originally Posted by Trebuchet View Post
    Formula 1 car racing restarted last weekend; they too are using rainbow symbolism. They have probably the worst rainbow I've ever seen. It's offensive to my inner Roy G. Biv.
    Second try for this post! Because I couldn't figure it out and still can't, but did realize that the rainbow is made up of colors associated with the teams. They use these in TV broadcasts. Except I'm not entirely sure which is which. Here's a more direct link to the rainbow. I hope.

    Anyhow, outside red is Ferrari. Probably. Because it's the oldest team.
    Orange is McLaren, certainly, and I think the second oldest team of the modern (post WWII) era.
    Yellow is certainly Renault, which is relatively new as a current entrant but I think the current team goes back to a previous iteration as Renault.
    Kind of an Aqua, is probably Mercedes, previously Honda, Brawn, BAR, and I think Tyrell. Goes back a while. Cars have never been that color as such but always had it as an accent.
    White is, what, maybe Williams? But there are at least four teams with predominantly white cars!
    Blue is, um probably Williams? But what's the white one?
    Pink is certainly Racing Point, formerly Force India.
    Then we have gray, black, red. The final red is most likely Alfa Romeo, although that's actually the Sauber team which has been around a while.
    Haas, the actual newest team is either the gray or black.
    That leaves Alpha Tauri, previously Torro Rosso, whose cars are predominantly white.

    Heck, beats me. I'll see if I can sort out the colors in this week's race.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

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    Hmmm... Verizon thinks the sites linked by Trebuchet are dangerous, and blocked them.


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    Quote Originally Posted by Extravoice View Post
    Hmmm... Verizon thinks the sites linked by Trebuchet are dangerous, and blocked them.


    Sent from my iPhone using Tapatalk

    Cool! It's Formula1.com! Which as far as I know is the official site of a major sports business.
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

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    It seems a waste of the opportunity, but someone really really interested cold aim for a wet atmosphere during a total solar eclipse and try to catch the higher-order rainbows during the near-totality phases when the colors are purer. Some colleagues reported seeing a breathtaking set of solar halos during the 1979 eclipse in Oregon as the reappearance diamond ring brightened (although nobody got photos - catching the right exposure unplanned would have been enormously tricky, even if most of the film roll hadn't been used for totality).

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    Very interesting, it strikes me that if observing inside a good fog of mixed droplets, the many possibilities combine to near white in all directions, one needs a special distant perfect fog to get the higher orders. I played with smoke ring generators (to deliver a bolus to a person) which can be adapted to make fog rings, and an engineered fog ring might be very pretty.
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