Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I What caused a rainbow near the setting sun?

  1. Dec 18, 2016 #1
    About a half-hour before sunset I saw part of a rainbow extending upwards from the horizon about 10 degrees. All seven colors from red to violet were visible from left to right, but they were somewhat faded out. What caused this partial rainbow which I saw about 30 degrees north of the setting sun? As the sun set, the rainbow gradually faded out completely.

    The setting sun itself was quite a sight also. Unfortunately I am not a photographer. I do not even know how to take a picture with my cell phone.

    A red-golden sun started out about ten degrees above the horizon. Above was a dark gray cloud bank extending from abut 60 degrees south of the sun to about 20 degrees north of the sun. Below the dark clouds were lines of thin golden clouds extending out radially from the direction of the sun.
     
  2. jcsd
  3. Dec 18, 2016 #2

    anorlunda

    User Avatar
    Science Advisor
    Gold Member

  4. Dec 19, 2016 #3
    Hi @anorlunda:

    Thanks for your interesting post. What I saw did not resemble any of the photos in the article you cited. The odd characteristic of what I saw was the rainbow colors near the sun, only about 30 degrees away. All other rainbows I have ever seen had an azimuth about 160-180 degrees away from the sun.

    Regards,
    Buzz
     
  5. Dec 19, 2016 #4

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor
    2016 Award

    It's hard to say for certain, but from your description it could have been a 22° Halo:

    http://www.atoptics.co.uk/halo/common.htm
    http://www.atoptics.co.uk/halo/mdisp6.htm
    http://www.atoptics.co.uk/rainbows/notabow.htm

    But there are other, less common, atmospheric effects as well- atoptics is a great site.
     
  6. Dec 19, 2016 #5

    anorlunda

    User Avatar
    Science Advisor
    Gold Member

  7. Dec 19, 2016 #6
    Hi @anorlunda and @Andy Resnick:

    Thank you both for your responses. It seems likely that a partial 22 degree halo (the lower part near the horizon near sunset) is what I saw, except that as I remember it, red was closest to the sun rather than away. However, my memory could be playing tricks with me. I am going to have to learn how to take pictures with my cell phone.

    EDIT
    I previously misread the description at the atoptics site. It says:
    Each 'dog' is red coloured towards the sun.​
    So what I saw was probably a sundog.

    Regards,
    Buzz
     
  8. Dec 19, 2016 #7

    anorlunda

    User Avatar
    Science Advisor
    Gold Member

    Now it is my turn to thank you. I missed sun dogs in the Insights article, so I just went back and added a new passage and a new picture to the article.

    Very bright sun dogs in Fargo, North Dakota. Also visible are parts of the 22° halo (the arcs passing through each sundog), a sun pillar (the vertical line) and the parhelic circle (the horizontal line).

    Fargo_Sundogs_2_18_09.jpg
     
  9. Dec 19, 2016 #8

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor
    2016 Award

    Here's a lunar version:

    DSC_2395_zps9cytqiql.jpg

    The 22° halo is clearly visible, there's also a moondog (paraselene) and a bit of the paraselenic circle.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: What caused a rainbow near the setting sun?
  1. What causes this? (Replies: 1)

Loading...