This picture was taken with my new Canon 100mm f/2.8 Macro lens, simply because it was the lens that was on my camera. I was testing my lens on flowers and insects when I suddenly looked up and saw the perfect contrails on the perfect blue sky. I took three shots with manual focus, and this was the sharpest one. It just proves that this lens has many uses. This image is priced at $50 (royalty-free) as part of the PhotoShelter Collection.
Being a meteorologist, I feel compelled to explain what contrails are. As jet aircraft enter the cold air just below the stratosphere, they trigger the formation of ice crystal Cirrus clouds. The exhaust of the engines provides the condensation nuclei necessary to produce clouds from the water vapor already present in the surrounding air. According to the IPCC, contrails contribute to global warming.
Erik Kolstad's photo blog 