When most people think of clouds, they picture these liquid water clouds, which exist closer to the Earth's surface and are responsible for rainstorms and other weather, Cziczo said. Unlike liquid water clouds, which generally cool the Earth by reflecting sunlight, ice clouds can help warm it up by absorbing reflected heat, Toon said.Ĭirrus clouds are unique in that they are made up of ice crystals, whereas most other clouds contain condensed droplets of liquid water. Depending on their location in the atmosphere, they can either help cool the Earth or warm it up. It's also unclear how cirrus clouds might affect the climate. (Image credit: Courtesy of Karl Froyd, NOAA and CIRES) Instruments behind the front of NASA's WB57F airplane, used to collect cirrus ice cloud crystals and the particles that help them form. Toon said more mineral particles kicked up by humans could equate to more cirrus clouds, although there are many other factors that complicate the situation. Metallic particles are also introduced by humans through the burning of fossil fuels and other industrial activities, he said.īut how does this affect the amount or size of cirrus clouds? It's too early to say, Cziczo said, but the data from the study will help improve computer models of climate change. Cziczo estimates that the level of these minerals has increased by about 50 percent since the beginning of industrialization.
Although mineral particles have always found their way into the upper atmosphere, where cirrus clouds hang out, humans have increased the amount of mineral dust that arrives there through land-use changes such as deforestation and land development, Toon said. The new study shows, however, that humans actually impact the formation of cirrus clouds (just as climate change affects cloud formation and vice versa, in little-understood ways), by sampling the ice crystals making up the clouds and seeing what particles they formed on.
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