January 04, 2013 Posted by: BW

A beautiful phenomenon with a funny name, hoar comes from Old English and means grayish white or gray-haired with age. This type of frost forms large white crystals on cold surfaces. It is easy to see how the feathery crystals can make things look hoary! These large crystals form when we have cold nights with no wind but still plenty of water vapor in the air. The vapor transitions directly from a gas to a solid in a process called deposition. The morning is the best time to look for evidence of this occurring throughout the park because the fragile crystals are melted quickly by the sun. So where would be a great place tolook for hoarfrost? How about under the Maclure Glacier?  The lack of sunlight and wind, along with plentiful humidity, allow for the formation of large galleries of gorgeous hoarfrost crystals. Of course, right now the glacier is buried under snow along with the rest of the high country, so you may want to stick to looking near the snow covered trails, low plants, and fence rows of the more easily accessed parts of the park. Any surface that would be chilled below freezing during the night could wake up covered in hoarfrost. 

 Hoarfrost on the snow-covered pines near Badger Pass  Hoarfrost under the Maclure Glacier

Hoarfrost on snow-covered pine trees near Badger Pass

Hoarfrost underneath the Maclure Glacier


Yosemite Valley, BW

Last updated: February 16, 2013

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