A cloud is a cloud, is a cloud. But scientists have now found that at least some clouds contain biological particles that can be genetically analyzed to show where the cloud came from.
In the case of a study presented last week at the Ocean Sciences Meeting in Honolulu, the clouds were over the Arctic Ocean and the particles were microgels -- snot-like substances containing proteins -- created by algae that live on sea ice.
The discovery that the carbon-based products of living things in the oceans are part of the process that creates clouds is a major shift in understanding ocean clouds, and therefore a rather crucial matter, say scientists, because clouds play a very important role in the models that are used to study climate.
"It's a whole new paradigm," said chemist David Kieber of the State University of New York in Syracuse. “And it is important because understanding clouds is key.”
Since the 1950s most scientists thought that over the oceans, where there's usually not a lot of dust to serve as the seeds for cloud droplets, the role was filled by salt particles. That turns out to be wrong.
“A lot of people are still back in the '50s on this matter,” said Kieber. “Honestly, in the '70s and '80s everybody thought it was salt. Salt was the main thing.”
The cloud-forming microgels were the focus of a talk by Monica Orellana of the University of Washington, who was part of team that used balloons with threads of monofilament line to collect water droplets from clouds over the Arctic ocean during an expedition in 2008.
“We went to the Arctic to look at aerosols because it's a simple system,” said Paty Matrai, of Bigelow Labs for Ocean Sciences. Matrai was was part of the expedition team. “The air quality in the center of the Arctic in summer is very clean.”
It's a great place to look for the organic inputs from the sea into the clouds, which they found.
“It means there is an intimate connection between the seawater and the clouds,” said Matrai. “It's a revolution in aerosol chemistry.”