Friday, December 9, 2011

Amazing Fog Pictures and Inversions

 Special Eclipse Forecast: I got up at 5 AM...and saw the eclipse begin...
 

Last night we developed a very strong inversion and a shallow fog layer that has now mainly burnt off.  At daybreak many land areas around the Sound had fog, while large areas of the Sound were clear.

Here is an extraordinary picture sent to me by Tracee Geernaert at a location on Salmon Bay, looking to the north.  You see those wave-like structures---reminiscent of breaking waves on a beach?   Stunning.  Those are examples of Kelvin-Helmholtz Instability (KHI) waves that are produced when there a very large change in wind with height over a layer of the atmosphere that is stable.


These are also called billow clouds.  Here are a few more examples:



Such clouds can be associated with substantial turbulence as they roll up and break.   Often quite turbulent to fly through.   A few years ago I was sitting in a window seat on an aircraft and saw those clouds ahead of us.  I told the person next to me that it would be a good idea to put on her seatbelt.  She laughed at me.  A few minutes later we hit moderate turbulence.  She wasn't laughing anymore.

Some beautiful shots this morning of the sun and shallow fog from the Queen Anne and Space Needle cams:



 Last night warm air moved in aloft and offshore flow increased.  As result the inversion aloft really cranked up.  Here is the temperature structure at 8:30 AM this morning over the Puget Sound region:
Around 30F near the surface, but in the mid-50s above 2500ft.  Very strong inversion!  Want to hear something amazing? The temperature right now (1 PM) at Mowich snotel site west of Mt. Rainier, at an elevation of 3150 ft, is 62F!  And it is 50F at Paradise on Mt. Rainer (5500ft).  Can you imagine?  You could be hiking in bright sun in 60F temperature right now!

Let me end with an extraordinary shot this morning  of the fog from Peter Benda's house at 1100 ft in Bellevue

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