Physics Photo of the Week

Warren Wilson College

January 28, 2005

Clouds before Ivan

The evening before the arrival of Ivan the Terrible Storm to Western North Carolina in September 2004, the clouds showed an amazing multiple dynamics.  Three types of clouds are seen in the picture.  The high clouds are cirrus clouds.  They are formed by warm, moist air flowing above cold air and usually indicate a prelude to stormy weather on the way.  At mid level - to the right of center - is a lenticular-like cloud.  This mid-level cloud shows a different shape from the lowest cumulous clouds just above the Craggy Mountains.  The three strata are better observed in the animation below.  Please have patience, the animated file is larger than 350 kilo-bytes - it may take awhile.  In the animation, however, one can see that the directions of the winds at various altitudes are all different.  The lowest clouds move toward the left (wind coming from the east) forming the clouds as the winds are deflected toward the summits of the mountains. The biggest "blob" of lenticular cloud appears stationary while bits an pieces travel toward the north - away from the camera.   The highest level clouds are moving from the west - towards the right hand side of the photo.

Animated Image
Image 350 kB.  Please have patience...

The animated image consists of 11 frames taken every 40 seconds and played back at 0.2 sec per frame.  Over 7 minutes of motion are compressed into about 2 seconds.  The images were made on the evening of Sept. 15.  The hurricane remnants (much rain, flooding, and high winds) came on the evening of Sept. 16, 2004.    -   Donald F. Collins

Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department.  These photos feature an 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

Click here to see all Physics Photo of the Week for 2005

Click here to see all Physics Photo of the Week for 2004.