JERUSALEM, Jan. 25 (Xinhua) -- Even the tiniest of particles from human emissions can fuel powerful storms, influencing crops much more than previously thought, a new study revealed by sources from the Hebrew University of Jerusalem shows.
The new study, which will be published in the Jan. 26 issue of the journal Science, focuses on the power of man-made emissions, which come from urban and industrial air pollution, wildfires and other sources, to bring rain clouds and big storms.
While scientists have known that particles in the man-made emissions play an important role in shaping weather and climate, the new study shows even the smallest of man-made particles can have an outsize effect, creating more severe thunderstorms which in turn, may lead to soil erosion, runoff and crops damage.
These tiny pollutants, less than one-thousandth of the width of a human hair, were long considered too small to have much impact on raindrop formation.
However, according to Dr. Jiwen Fan of the U.S. Department of Energy's Pacific Northwest National Laboratory, who is the lead author of the study, the presence of these particles is one reason why some storms become so strong and produce so much rain.
"In a warm and humid area where atmospheric conditions are otherwise very clean, the intrusion of very small particles can make quite an impact," he explained.
The study was conducted in the Amazon, a largely pristine, untouched area, where scientists studied the impact of pollution from nearby Manaus, a city of 2 million people in the Amazon.
While larger particles were known to enhance thunderstorms, scientists had not observed until now that even smaller particles, like those produced by vehicles and industry, could have the same effect, according to the second-author Prof. Daniel Rosenfeld from the Institute of Earth Sciences of the Hebrew University of Jerusalem, Israel's leading academic and research institution and producing one-third of all civilian research in Israel.
The new study revealed that the ultrafine particles could invigorate rain clouds and increase rainfall in a much more powerful way than their larger counterparts, said Rosenfeld.
"This groundbreaking research strongly suggests that mankind has likely altered the rainfall and weather in densely populated tropical and summer monsoon areas such as India, Southeast Asia, Indonesia, and even southeastern U.S.," he said.
Despite being small in size, these particles are large in number and serve as a platform upon which small water droplets congregate and excess water vapor condenses.
This enhanced condensation releases more heat, causing updrafts to become more powerful. The updrafts then could pull more warm air into the clouds, which ultimately produces more ice and snow pellets, lightning and heavier rain.
