Physics Photo of the Week

January 24, 2014

Sloshing Fog

This bleak, heavily overcast day in early December of 2013 showed an interesting layer of fog.  The fog most likely is caused by a layer of cold air sunken into the Warren Wilson Valley.  Notice how clear the air is below and above the fog layer.  Click on the above image for a larger view.

A time-lapse animation of this foggy mass is very interesting.  The overhead clouds are moving quickly toward the East, and the fog is sloshing around trapped in the valley.  The sloshing is similar to water sloshing around in a bathtub.  At the end of the loop notice that a "wave" of fog appears to crash into the Watch Knob mountain - similar to waves breaking on a rocky shore.  The animation was produced by taking an image every 10 seconds then playing back the short loop of 41 images at about 3 images/sec.  The playback speeds up the effect by a factor of 300 times.

Next week we will celebrate the Tenth Anniversary of Physics Photo of the Week!

Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to

All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion.  These photos and discussions may be used for private individual use or educational use.  Any commercial use without written permission of the photoprovider is forbidden.

Click here to see the Physics Photo of the Week Archive.

Observers are invited to submit digital photos to: