Open-cell and closed-cell cloud systems obscure the Pacific Ocean just off California (file photo).
Covering vast areas of the ocean at any given time, such systems play a major role in regulating the amount of sunlight that reaches the planet. And since little is understood about clouds' effects on temperatures worldwide, cloud cover remains something of a wild card in global warming predictions.
The new study, though, could shed some light on what causes overcast, "cooling" cloud systems vs. open-cell, "warming" systems to form. According to the study, computer simulations show that cloud patterns are greatly influenced by the amount of aerosols in the atmosphere.
Aerosols are tiny, floating particles, such as the soot generated by burning fossil fuels. Water in the atmosphere tends to condense around aerosols, so more aerosols mean more water droplets and thus denser, closed-cell clouds, which are less prone to raining.
And because rain appears to be the trigger for open-cell clouds to form and reorganize, Wang said, "less rain may keep the clouds in a closed-cell pattern."
(See "Surprising Clouds Forming Due to Lead in Air.")