Flagged Trees and Lenticular Cloud

May 10, 2010


Photographer: Mario Freitas; Mario's website
Summary Author: Mario Freitas

The prevailing wind direction over a particular point on the Earth's surface is strongly influenced by global circulation cells in the atmosphere; blowing westwards at low and high latitudes and eastwards at mid latitudes (35 to 65 degrees). The above photo depicts two distinct effects of winds blowing southeastwards on a peninsula near Grey Glacier in Chilean Patagonia (Torres del Paine National Park). Continuous exposure to fierce winds coming from the same general direction caused the trees at bottom foreground to become distorted and predominantly flagged – branches growing away from the direction the wind is blowing. Additionally, as air is forced to rise over elevated terrain, the Andes Mountains for instance, clouds having almond or lens shapes (Altocumulus lenticularis) form on occasion in lee waves. The impressive lenticular cloud at top, which was nearly stationary with respect to the underlying terrain, formed in air moving from the same quadrant as the gales responsible for the flagging the trees. Note the iridescence around its edges.

Photo details: Canon A710 camera; focal length 5.8 mm; shutter speed 1/1250; aperture value 5.6; ISO speed Auto.