New research has been published on how cirrus clouds are formed. Cirrus clouds can be identified by their wispy strands, and have a big effect on global climates because of their ability to absorb radiation and trap heat.
A study funded by NASA and the National Science Foundation recently took samples of cirrus clouds using research aircraft. The study found that a majority of the cloud particles form around two types of "seeds": mineral dust and metallic aerosols.
"We think we're really looking at the seed, the nucleus of these ice crystals," Dan Cziczo, associate professor of atmospheric chemistry at MIT, said to Phys.org. "These results are going to allow us to better understand the climatic implications of these clouds in the future."
The research was conducted through four flight missions over a nine year period between 2002 and 2011. The clouds were sampled in North and Central America, where cirrus clouds are most likely to form.
Cziczo explained that while the team relied on weather forecasts to predict where the clouds would be, it was up to the pilot to actually snag the sample.
"More often than not, the forecast is solid, and it's up to the pilot to hit a cloud," Cziczo stated. "If they find a good spot, they can call back on a satellite phone and tell us if they're inside a cloud, and how thick it is."
Using a particle collector and mass spectrometer, the plane then extracts the ice particles, which would then thaw and be examined by the research team. After analyzing the data, the researchers found that over 60% of the particles were formed from mineral dust blown into the atmosphere, which points towards significant human involvement.
"There's been a lot of research efforts spent on looking at how these particle types freeze under various conditions," Karl Froyd, a researcher with NOAA's Earth System Research Laboratory, explained. "Our message is that you can ignore those, and can instead look at mineral dust as the dominant driving force for the formation of this type of cloud."