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Look up at the sky. What do you see? Depending on the weather, you might see a blue sky dotted with fluffy white clouds, gray clouds pouring down droplets of rain or even snow. However, researchers say that the sky may even qualify as an ecosystem. Hovering as high as 30,000 feet overhead, they have found bacteria, as many as 17 of which may live there full-time, that may have a hand in affecting weather patterns, climate and even the spread of disease.

The study, conducted by researchers from the National Aeronautics and Space Administration, was performed in 2010. As the scientists rode aboard a NASA aircraft, instruments on board the vehicle sampled the air in the upper troposphere before, during and after the Hurricanes Earl and Karl. As the Los Angeles Times explains, the researchers focused on an RNA gene called SSU rRNA, which can accurately identify bacterial species.

Researchers found that there were 144 bacterial cells per each cubic feet of air and, according to Nature, found 314 different types of bacteria in all. Scientific American reports that, in total, there were 5,000 bacterial cells. They also found fungi, though in less concentrated amounts than bacteria. While they found that bacterial populations were vastly different before and after the storm, indicating that many bacterial species were kicked up into and washed out from the atmosphere, 17 species were found in every sample, suggesting that they live there. The bacteria appears to have developed the ability to withstand freezing temperatures, ultraviolet radiation and scarce feeding supply.

Researchers also found some plant-based microbes, which typically freeze plant leaves and invade. In the air, that power could be used to amass water vapor and small clouds, triggering rain.

The findings could also hold implications for the spread of illness. Study co-author Athanasios Nenes said to the Los Angeles Times, "Once you get to that altitude, if you can survive, you can basically circulate the Earth very quickly. You can start out in Europe and end up in Asia."

The study was published in the journal Proceedings of the National Academy of Sciences.