Physics Photo of the Week
January 20, 2012
Beynard Cells
The photograph at left is looking
down into a beaker partially filled with a fluid containing
a suspension of small aluminum flakes. The beaker (a
glass container) is gently heated from below. The
suspension of aluminum flakes enhances the visibility of the
resulting convection. The convection consists of a
semi-random pattern of cells called Beynard cells. The
warm fluid rises in the center of each cell, flows outward
from the center to the darker cell walls and descends to the
bottom of the container to be re-heated again. 
On a desktop these cells are a physical curiosity. However, they are responsible for much micro-meteorology of atmospheric circulation as seen by the photo of alto-cumulus clouds at right. The clouds form in the rising thermal cells with cooler air descending between the clouds.
Similar cells outline the
thermal convection on the surface of the Sun away
from sunspots. Solar convection cells seen in high
resolution telephoto images are called "Granules". The
photo at left (courtesy of Vacuum Tower Telescope, NSO, NOAO)
was published on Astronomy
Picture of the Day for 2005 Nov 6. _____________________________________________________________________
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 dcollins@warren-wilson.edu.
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.
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