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.







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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.

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