With cold temperatures, low humidity and high levels of ultraviolet (UV) radiation, conditions 10 kilometers above Earth’s surface may seem inhospitable. But next time you’re flying, consider this: The air outside your airplane window might be filled with an array of microscopic life that affects everything from weather and climate to the distribution of pathogens around the planet.
In the first detailed study of microbes in Earth’s upper troposphere, a group of scientists has found populations of bacteria that — although they don’t rival the size and diversity of microbial communities in the oceans, soils or air at Earth’s surface — are startling all the same. While participating in several NASA-sponsored research flights intended to study atmospheric conditions related to hurricanes, the scientists collected samples of airborne biomass — most at about 10 kilometers altitude above the Gulf of Mexico and the Caribbean Sea — near two late summer 2010 hurricanes, Earl and Karl.
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