Cumulonimbus clouds as seen from an airplane flying above 30,000 feet. (Photograph: © Tom Yulsman) I'm spending much of my Fourth of July jetting across the country. So I thought I'd take advantage of my window seat, along with the WiFi on the aircraft, to wish everyone a very happy Independence Day with an ImaGeo picture postcard. I shot this photo with my iPhone somewhere over Oklahoma or Arkansas. Classic cumulonimbus clouds have boiled up to an altitude above 30,000. I was particularly taken with the detail in the clouds, and I thought it would look particularly compelling in black and white. So I converted it, used a red filter to darken the sky a bit, and boosted the contrast. I hope you are enjoying your own slice of nature wherever this 4th of July may have taken you.