Cloud Shadow but in the Sky

The photo above was taken by Dan Gingerich. It is the Hot Shot photo at 5 pm today. It was taken in Decorah. I was not sure exactly why the shadow looked the way it did in the sky. When it comes to atmospheric optics the #1 source is Les Cowley. He runs a GREAT web page. 

I have asked him questions before and he ALWAYS has the answer. So I went to him again to help me out. Here is what he had to say about the photo above.

Cloud shadows and rays can, like these ones, be very counter intuitive! 

The dark shadows look like they are pointing upwards but in reality they are angled downwards – all shadows cast by the sun must go downwards.      

There is a thin layer of hazy cloud _below_ the top of the towering cumulus.    The sun is casting a shadow of the cumulus cloud onto this lower layer.   We see the shadow through the other side of the lower cloud layer ‘screen’.     The shadow looks above the cumulus cloud simply because the shadow is closer to the camera.   See the diagram here:


Posted under Optics

This post was written by Schnack on January 17, 2013

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