Sulfuric acid may help soot turn into cloud seeds

March 26th, 2009 - 12:50 pm ICT by ANI  

Washington, March 26 (ANI): In a new research, scientists have determined that as soot particles in the atmosphere age, airborne sulfuric acid may help turn them into condensation nuclei, which enable the formation of clouds.

The research was conducted by Alexei F. Khalizov and colleagues from Texas A and M University, who worked alongside researchers from University of Minnesota, and Lund University, Sweden.

Carbon soot aerosols from combustion of fossil fuels and forest fires directly influence the Earth-atmosphere heat balance by absorbing sunlight.

Fresh soot particles repel water and hence have little effect on properties and lifetimes of clouds.

But, as soot particles age, they are thought to undergo a weathering process that allows them to absorb water, potentially transforming particles into cloud condensation nuclei.

To learn more about how soot develops an affinity for water, Khalizov and his team examined the properties of soot aerosols exposed to gaseous sulfuric acid.

They found that although fresh soot does not change below water saturation, soot particles exposed to sulfuric acid increase in mass when relative humidity rises because the acid-coated soot absorbs water.

An increase in particle mass is often accompanied by a decrease in size, suggesting that conventional measurement methods based on particle size may underestimate the impact of soot aging on clouds.

Because sulfuric acid, a pollutant and the driving agent in acid rain, is increasing in the atmosphere due to industrial activities, the researchers expect that this mechanism of water absorption by acid-coated soot significantly influences cloud formation. (ANI)

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