Look for cloud systems while you fly
Watch the Clouds. You don’t just have to look down. Some of the most interesting sights are meteorological—on any flight of more than a few hours, you’re bound to witness at least one complete frontal system, and a range of cloud formations. To keep track of the vast menagerie of clouds, get a copy of The Cloudspotter’s Guide by Gavin Pretor-Pinney, with extensive (and effusive) descriptions and photographs.