Thursday, February 05, 2009

When Sunny Means Foggy

This time of year on Powell Lake in Coastal BC a forecast for sunny days isn't always good news. During winter months it's common for Powell Lake to become enshrouded with a mantle of low lying fog. You might call it ground fog, but it starts on the surface of the lake. Ground fog and valley fog are forms of radiation fog. Conditions leading to radiation fog include:

  • clear skies
  • light winds
  • shallow layer of cool moist air near the ground
  • long nights
Powell Lake fills a steep glacial carved valley and is susceptible to valley fog. The NASA website states:
Valley fog forms on clear winter days when heavy cold air settles into the mountain valleys while warmer air moves over the surrounding mountains. Fog forms when the frigid ground cools the air immediately above it. The cooling air thickens into fog as water condenses. Air farther from the Earth’s surface is warmed by the sun, trapping the layer of cold air beneath it. The condition is called a temperature inversion, and it can last several days.
When the fog begins to clear it typically moves from north to south down the lake. From the deck of our float cabin we can often see it flowing back through First Narrows.


Thanks for visiting! -- Margy

13 comments:

  1. Fog or no fog - it is very beautiful there!

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  2. Very cool. I like the picture with the wake from the boatit looks likeyou are trying to out run the fog.

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  3. Great pictures of the fog. I saw your post about the Arlington Airport. I work across the street from there and enjoy watching the planes fly in and out. Thanks for stopping by blog.

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  4. Hi Margy,
    Thank you for stopping by and linking I will be pleased to do the same.

    Your photos and info on fog are great. I love to know about things also.

    Your site has be on my favourites list before I got back into blogging and I have gone there often to read about your float house experiences, your trip from California and of course your SkyWatch Friday pictures. Your blog is very informative.

    Thank you for sharing and thank you for coming by.
    Smiles
    P.S. You know Powell River isn't very far away!?!

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  5. Awesome photos..that fog is so thick!
    I am familiar as I lived in BC for a while!

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  6. Great fog shots. I live up fairly high looking down into the valley and sometimes it looks like the ocean in the valley because it's foggy there but not where I am. That might be a blanket of fog.
    You have a super blog full of neat info. Thanks for visiting. MB

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  7. So beautiful and impressive!

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  8. I didn't have the foggiest idea, but you've explained it so well, with great pics, so now it's all become clear...so to speak!

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  9. This is absolutely stunning, I have to admit I am quite partial to a nice bit of fog! Thank you for visiting my Skywatch entry and your kind comment too :)

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  10. Incredible photos, I truly enjoy your blog every time I visit.

    Have a great weekend!
    Guy
    Regina In Pictures

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  11. Thanks for visiting my blog. Love you site, beautiful pictures.

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  12. amazing photos! Fog certainly lends a quality to master and you have!

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