Monday, January 21, 2008

Heads or Tails: Hoarfrost

On January 10th, I took photos of what I thought was wind blown ice formations on the Missisquoi River during the January thaw. I was wrong. What I saw is more interesting than that. It is surface hoar, a type of hoarfrost. You can see it in the above photo at the edges of the snow. In the photo below, it is in the foreground and looks like diamonds in the sun.

The Guide to Frost at SnowCrystals.com describes surface hoar:
The most common form of hoarfrost is called surface hoar. This consists of ice crystals that form on top of snow banks, usually overnight. The sparkles you see coming from a field of snow are often reflections off the facets of surface hoar crystals.

Surface hoar typically forms when a snowbank warms up during the day and is then cooled again overnight. The night air cools the surface of the snowbank more than the inside, so that water can evaporate from inside the snowbank and recrystalize on the surface. By morning the snowbank is covered with a layer of faceted ice crystals, and they can be quite large. These usually melt again once the sun comes up, so the best time to find surface hoar is early in the morning.

Surface hoar is a delight for our eyes.

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26 comments:

  1. I have never even heard of surface hoar before. Whatever the name, it sure is beautiful and interesting.

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  2. Very interesting post. I did not know what hoar frost was. It is amazing how cold it is all over the US right now.
    --JB

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  3. It does look like diamonds. Beautiful!

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  4. Cool. Thanks for the education; I knew the term but not what it meant.

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  5. Absolutely beautiful! I just love learning new things! I've never heard of hoars, surface or otherwise! LOL! Cold enough for you? I see at the time I'm commenting that it's about 1F in Barton. We're at about 10F here in Guilford....downright balmy! LOL!

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  6. Those are great photos! Thanks for teaching me. :)

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  7. Surface hoar may be easy on the eyes, but its hard as heck to walk on! I'm usually pretty graceful, but that stuff is slippery AND uneven which = a sore butt.

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  8. That was the most interesting post I've read so far this whole past week...I learned something today, thanks to you.

    Excellent photos to by the way.

    My HoT is posted. Drop by if you can, okay?

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  9. Diamonds in the sun ... that's a perfect description. The reflection of the sun makes it sparkle.

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  10. You know, I've probably seen this...but never realized there was a name for it. Now I'll know.

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  11. I have never heard of surface hoar before either...but it sure is pretty...what do you think the temperature was?

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  12. I had never heard of these, they look very interesting thanks for sharing

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  13. That's really cool, I'd never heard of that before! I love that you added pictures - Happy HoT :-)

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  14. I always wondered what that meant, and now I know! Now that I know, I know I've seen it too.. and it IS beautiful. :)

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  15. Interesting post. Frost a lot that in here in Wyoming. Also snow...

    mine is here http://www.happymomiam.us

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  16. I've heard the term hoarfrost before, but I didn't know what it was. How pretty!

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  17. Great pictures and thanks for the explanation. I have seen hoar frost before, but I did not know it had its own name. I sure love learning new things.

    Happy Tuesday.

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  18. Great frosty and visual H or T! (Thanks for visiting mine.)

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  19. Lovely pics - and a very informative Heads or Tails. Thanks for posting - it was a pleasure to read. Happy Tuesday!

    My Heads or Tails is up at Siani's Pot-Pourri.

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  20. I have heard the term hoarfrost since I was a kid and mother and daddy used to point it out. Thanks for a great memory!

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  21. What an interesting post! Great Photos!

    www.mamapj.com

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  22. Very good photos. I'm not really familiar with "hoar" but I have seen the crystal like appearance in snow. I learned something new :)

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  23. Oh, I forgot to mention that the radio I got for Skittles car also has an input cord that hooks up to our ipod and also controls it too :)

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  24. Very good explanatory material...that kind of research is what makes picture taking more interesting and documentative! Great work!

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