January 21, 2009
If the universe seems cold from a distance, birthdays are part of its rebuttal.
A Lenticular Cloud Over New Zealand
Birthday · January 21, 2009
A little universe, just for you
Your date.
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APOD published January 21, 2009. Credit: Chris Picking. A publication-date match, not a photo taken on your date. Independent of NASA.
What's happening above those mountains? Several clouds are stacked up into one striking lenticular cloud. Normally, air moves much more horizontally than it does vertically. Sometimes, however, such as when wind comes off of a mountain or a hill, relatively strong vertical oscillations take place as the air stabilizes. The dry air at the top of an oscillation may be quite stratified in moisture content, and hence forms clouds at each layer where the air saturates with moisture. The result can be a lenticular cloud with a strongly layered appearance. The above picture was taken in 2002 looking southwest over the Tararua Range mountains from North Island, New Zealand.
Image credit: Chris Picking