Smoke Changes Cloud Cover, Climate: NASA
In the dry season in Amazon smoke creates large number of pollution over the place. A photograph has taken from airplane in 2005 to see how the clouds look like:
Researchers from NASA and other institutions have identified the common thread that determines how aerosols from human activity, like the particles from burning of vegetation and forests, influence cloud cover and affect climate. The study improves researchers’ to predict whether aerosols will increase or decrease cloud cover. Lorraine Remer, a physical scientist at NASA’s
“Scientists have observed instances where increases or decreases in the amount of these tiny particles have increased and decreased cloud covers in different places and times,” said Remer. “We saw an example of these ourselves: increased aerosols over the Amazon produced less cloud cover. Over the
To test their model, Remer’s team used aerosol and cloud observations from NASA’s Terra satellite of the Amazon during the 2005 dry season the season offers stable weather conditions and an abundance of human-caused aerosols from fires, set to clear new land and burn through old pastures to prepare the land for the next crop season. Aerosols are the tiny particles that make up smoke, dust, and ocean spray. Traveling on wind currents, aerosols move from their source and into the atmosphere, where they become individually encased by water and turn into the droplets that combine to create clouds. Cloud microphysics makes clear that the larger the number of aerosol particles suspended in air the less water in the atmosphere is available for condensation on each individual particle. Under these conditions, a cloud will have a much larger number of small droplets. The smaller the droplets, the longer it will take for a cloud to rain. Aerosol-rich clouds like this spread out by winds, produce less rainfall, and last longer, creating more cloud cover. However, aerosols also influence clouds through their ability to absorb heat from the sun. The trapped heat causes the atmospheric layer to warm up, and changes the environment in which the cloud develops. The overall result is to make the environment less hospitable for cloud growth. Even the smallest resulting changes in cloud cover can significantly warm or cool the atmosphere and change when and where fresh water will be available in the region.” As we’d expected in applying our model, increased smoke from the fires created clouds rife with a more pronounced radioactive effect – rich with human-caused aerosols that absorbed sunlight, warmed the local atmosphere, and blocked evaporation. This led to reduced cloud cover over the Amazon,” said co-author Martins.
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