Scientists have found a world of bacteria and fungi floating about 30,000 feet above Earth. Athanasios Nenes of Georgia Tech and his colleagues hitched rides on a NASA aircraft that sampled the air before, during and after hurricanes Earl and Karl in 2010. They reported in the Proceedings of the National Academy of Sciences finding 17 types of bacteria that must have developed traits that allowed them to bear freezing temperatures and survive in an environment bombarded by ultraviolet radiation. Microbes with this freezing ability could conceivably seed clouds and affect the way illnesses spread. "Once you get to that altitude, if you can survive, you can basically circulate the Earth very quickly," Nenes said.