14 DAY TRIAL // For many years, atmospheric scientists have been trying to determine how and why clouds catch on the variety of shapes and forms that they do, and two new studies finally provide a clear view of that.
According to investigators, it would appear that the origins of the aerosols – small particles in the atmosphere that create the clouds – is the most important factor in determining cloud shape.
In other words, the structure looks very much like where they came from. The two research papers detailing the idea and the evidence to support it appear in the September 17 issue of the top-rated journal Science, Wired reports.
One of the investigations, which was conducted in the Amazon rainforest, shows that clouds here mostly originate in the gases that plant emit. The work was conducted in one of the most pristine environments on the face of the planet.
According to paper coauthor Scot Martin, an environmental chemist at Harvard University, the rainforest is a system in which “the plants cause the rainfall, and the rainfall causes the plants.”
University of Washington cloud scientist Robert Wood, who was not involved in any of the new researches, says that this investigation “demonstrates the importance of combustion-produced aerosols for controlling cloud-forming particles.”
Both studies contribute to “areas that so far have been nearly white spots on the landscape of aerosol information,” adds Paul Scherrer Institute expert Urs Baltensperger. The Swiss expert authored a Perspectives article in Science, accompanying the two papers.
The second study was basically a compiling analysis of 12 experiments that have been conducted in this field of research over the past 15 years.
The work was conducted by a team of scientists led by Anthony Clarke, who holds an appointment as an atmospheric scientist at the University of Hawaii.
“This paper impresses by its wealth of data, many of which stem from areas where very little data has been obtained so far,” Baltensperger writes of this work.
One of the main conclusions in the study was that the aerosol particles that were produced from human activities were very likely to go on and form clouds, by interacting with light.
A worrying implication for this finding is that, if two regions have the same number of aerosols, then the one with the most man-made fine particles in the air will go on to develop clouds.
“In cloud formation and in radiation transfer, larger particles that are sourced from combustion can play a more important role,” Clarke says.
“Of course everybody wants to know, what’s the effects of all this? Unfortunately that’s not easily done without very complex models. But there is data out there now for modelers,” he concludes.