Monday, November 7, 2011

Cool Clouds: Contrails and Maples

You can see glistening sunlight in this picture. And a bright blue sky. And the edge of a golden-leaved maple tree. But do you see a cloud?
Yes! As luck would have it, as I snapped this photo a plane was cruising across the sky, leaving behind a contrail. A contrail is a cloud—a stream of water vapor produced by exhaust from an aircraft’s engines. When the hot exhaust gases come into contact with the much cooler air, they condense into tiny water droplets and form a temporary cloud trail. Pretty cool.

 

I made sure to get just the edge of my maple in the contrail photo because I really want to talk about it today. Despite the terrible storm last week, the tree (left) still has most of its leaves.

I thought I remembered the tree losing it’s leaves right around Halloween, so I went back to my archive to find a photo of the tree from 2009 (below). That tree is almost bare.
The tree started to turn yellow at the same time both years. That means the tree is holding on to its leaves longer this year. I wonder why. Does it know something we don’t about the winter to come?

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