Physics Photo of the Week

Physics Photo of the Week March 20, 2026   Ice Sprouts - Photos by Henry Willis; Discussion by Donald Collins My friend, Henry Willis, sent me this photo of "ice sprouts" taken during a trek in the Great Smokies National Park earlier this winter.  Although fairly common, ice sprouts this large are quite unusual.  These sprouts are about 2 inches tall.  Ice sprouts are formed when bare ground, that has been saturated with rain water, freezes.  The amazing property of water is that the ice phase is less dense than water.  Ice cubes float on top of your drink of iced tea.  Most solid objects are more dense than their liquid counterparts.  When the muddy soil freezes, the freezing takes place on the top of the mud. The frozen surface confines the remaining water beneath the surface.  The remaining water under the top shell freezes and expands; pressure builds up and the expansion force breaks through cracks in the shell; the water is forced out a...