New York: NASA researches have discovered how aerosols from human activity, like particles from burning vegetation, influence the cloud cover and ultimately affect the climate.

"We connected the dots to draw a critical conclusion, and found evidence over the Amazon that traces the direct path of the effect of human activity on climate change by way of human-caused aerosols," said the study's co-author Lorraine Remer, a physicist at NASA's Goddard Space Flight Center.

Aerosols are the tiny particles that make up smoke, dust and ocean spray. Traveling on wind currents, aerosols move from their source into the atmosphere, where they become individually encased by water and turn into the droplets that combine to create clouds.

Aerosols are known play an essential role in how clouds develop. Accordingly, a team comprising Remer, Ilan Koren of Israel's Weizmann Institute and J. Vanderlei Martins of the University of Maryland set out to explore one of the least understood aspects of climate change caused by human activity.

"Scientists have observed instances where increases or decreases in the amount of these tiny particles have increased and decreased cloud cover in different places and times," said Remer.

"We saw an example of this ourselves: increased aerosols over the Amazon produced less cloud cover. Over the Atlantic Ocean, however, increased aerosols actually produced more cloud cover.

"We wanted to know what the link was between these different outcomes from varying amounts and types of aerosols. This paper gives us a clear picture of what is occurring."

The team developed an analytical model that combined knowledge of cloud development, satellite observations and mathematical calculations of aerosol concentration and cloud properties in an effort to explain how the two opposing effects of aerosols on clouds can influence cloud coverage and life cycle.

"This result helps us understand aerosols' effect on a cloud's mass and lifetime - how long it will provide cloud cover, how deep the clouds will be, and when and where it will rain," said Remer.

"This improved understanding leads to prediction and prediction can help us plan and perhaps prevent some of the potential consequences of putting aerosols from human activity into the atmosphere." IANS