changing sky

It was a good morning for a walk at the Valley Forge National Historical Park.

The sky was pure blue when I started with an occasional puff of a white cloud decorating the blue. As I walked the inner loop of the Joseph Plumb Martin trail the steady wind blew dark gray clouds in, obscuring the sun. A few raindrops fell.

As I was driving back, a band of heavy rain appeared. It disappeared quickly, leaving the sky blue again.