Wednesday, May 28, 2014

Mushroom Shaped Cloud Over Oregon

This was 12 minutes north of Crater Lake on Alaska Airlines from LA to Seattle almost 4pm PDT.  Actually, there were two of these clouds side by side.

The dark spots are dirt on the plane window.  I'm looking west.

This was the first one (southern) that we came to.

I couldn't find much about mushroom shaped clouds on line other than nuclear clouds.  There was an article in The Guardian that discussed non-nuclear mushroom shaped clouds.
However, mushroom clouds are not unique to atomic explosions. Any sufficiently powerful source of heat, such as a volcano or forest fire can produce one. The heat creates a powerful updraught, channelling dust and smoke from the ground into a narrow chimney, forming the stalk of the mushroom. This chimney continues to rise until it meets an obstruction in the form of a boundary layer in the atmosphere. The rising column then spreads out and forms the cap of the mushroom.
National Atlas has a map of potentially active volcanoes in Oregon, but I don't know that any created these.  

Wikipedia has a picture of a cumulusnimbus cloud which it calls an anvil cloud.  The stalk is a lot narrower than the two above. 
Wayne Flann Avalanche blog has a picture of a mushroom shaped cumulus cloud.

I expect that these two clouds would not have been as obvious, or even visible, from the ground.

BTW, here's a picture of Crater Lake which we passed 12 minutes before the clouds above. 


  1. Looks like a perfectly normal cumulonimbus to me. I'll see if I can find a live observation somewhere near there, but the automated weather stations don't provide the detail we live observers used to.

  2. Thanks, Anon, for the confirmation. We don't have clouds like that often in Anchorage and when we do, there tend to be lots of clouds all around - like in this case - so you wouldn't see it so clearly from the ground.

  3. Look like graduation mortarboards to me . . . . Must have been honoring some special folks. Thanks for the picture of Crater Lake! Grew up in the area and it's always a treat to see a photo of that very special place.

  4. They look like lenticular (lens) clouds to me, which I've seen frequently capping Mt. Rainier, but apparently they can form over even low hills.

    I wonder if the misty clouds under the lens clouds are being pulled up from the cumulus cloud layer underneath, in some sort of vortex air movement?

  5. Graduation Clouds! A whole new class of clouds, Anon.

    KaJo, I see what you're saying (seeing?)- but the pictures of the lenticular clouds look like the pancake, like top of the cloud formations above, but without the bottom. But the cumulunimbus have both the top and the stem. But I'm just going by what I can find online.
    Bill Butler - what do you have to say about this? Atmospheric phenomena are your area, and Oregon is your state?


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