Sun Pillar

Discussion in 'Miscellany' started by bobhoge, Jan 2, 2006.

  1. At sunset on December 30 we could see a sun pillar, a vertical shaft of light that is caused by the reflection of the sun off ice crystals high in the atmosphere. It is related to sun dogs and the like.
    [​IMG]
    [​IMG]

    There is a great website that describes in detail how this and other similar things occur:
    http://www.sundog.clara.co.uk/halo/pillar.htm

    Bob
     
  2. Johntu

    Johntu

    539
    Jul 4, 2005
    Fremont, CA
    Great shots. Thanks for sharing
     
  3. Gale

    Gale

    978
    Jan 26, 2005
    Viera Fl
    Excellent Bob,
    Great images..
    Wonderful catch on the sun rays..
     
  4. Chris101

    Chris101

    Feb 2, 2005
    Arizona
    Wow!!! I have been known to chase after dogs and halos. Pilars as well defined as this one are rare! Nice!
     
  5. Rob

    Rob

    873
    Jul 28, 2005
    Truro, Cornwall, UK
    This is a new phenomenon for me. I had never heard of Ice pillars, let alone all the others mentioned on the link. Great images, and something to watch for in the future.

    Just for information. The air cools with altitude at approximately 2*C/1000'. (actually 1.98*C). So it's worth considering at this time of year keeping an eye open for these pillars. If for example the ground temperature is close to zero, virtually all thin cloud layers that are observed above 5000' will be ice crystals, so pillars are possible.
    I'll stop now and let somebody else burst forth with the International Standard Atmosphere.:smile: :smile:
     
  6. Hi Rob,

    Thanks for the information, I had not thought about the temperatures needed for ice formation.
    These photos were taken in the southern part of Florida and it was probably 75ยบF outside at sea level. Do you think that made it more unusual to have the ice needed for the pillars? Obviously the ice was a bit higher in the atmosphere that you suggested.
    Bob
     
  7. wow, I learned yet another new thing today! Thanks for sharing Bob. A bit curious though as southern florida should not exhibit this to my thinking.
    Dave
     
  8. I've seen this phenomenon but wasn't aware of why it happened. We have such a widely intelligent group of people here. Always something to learn, no matter the subject.

    Bob, I like the shot too!
     
  9. Rob

    Rob

    873
    Jul 28, 2005
    Truro, Cornwall, UK
    Bob I'm going to try this from memory, so no mocking from you bods who Googled!:biggrin:
    75* F is 23.8888888888888889*C honest.:smile:
    The ISA (International Standard Atmosphere) is agreed to be at sea level, a temperature of +15*C, pressure 1013.25 Mb, temperature will reduce by 1.98*C/1000' to -56.5*C at 36,090' whereupon it will roughly remain constant. (But in fact gets a lot colder, but at a different rate.

    So, as you have no doubt worked out already, the icing band, generally accepted as being between +2*C to -2*C (although some use +3*C) lies somewhere in the region of 10-11,000' in the Florida rum consumption zone. Anything above that may be considered frozen, but often in fact may still be liquid, although super-cooled.................don't go there, please, this hurt me enough.:biggrin: :biggrin:
     
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