Shadows in the Sky

Another in the "Optical Phenomena at Lakehurst Naval Air Station" series.

This time shadows in the sky.

I'm not sure if these are clouds or contrail fragments that are causing these shadows.

But what exactly is the shadow been projected on?  The sky is made of air and air is transparent.

Hint, it is the same stuff clouds are made of.

If you guessed water vapor pat yourself on the back. You can see that the sky becomes increasingly white as it approaches the horizon. That's because we are looking through more and more of the atmosphere and the water vapor in it. Learn more about what's going on here.