WASHINGTON – Smoke drifting from burning forests in the Amazon is affecting the climate across the entire continent – drying up rain but making the storms that do develop much more violent than usual, scientists reported yesterday.
Smoke rises to the clouds, delaying the release of rain and allowing the clouds to grow taller than they otherwise would, the researchers said.
Higher clouds produce violent thunderstorms, and while less rain falls to the ground, it often comes in the form of hail and thunderstorms instead of more nourishing, gentle rains, they said.
Plus the storms push the smoke into higher atmospheric levels, allowing it to be carried far and wide, the international team reports in Friday’s issue of the journal Science.
“The invigorated storms release the latent heat higher in the atmosphere,” they wrote in their report. “This should substantially affect the regional and global circulation systems.”
The international team was funded by the European Union and headed by Meinrat Andreae of the Max Planck Institute of Atmospheric Chemistry in Mainz, Germany.
They measured whether smoke particles produce cloud droplets – the seeds of raindrops. A team at Hebrew University in Jerusalem flew special planes through smoky clouds over Brazil and measured how the smoke affected them.
They found the tiny smoke particles caused the water in the clouds to form minuscule drops that were too small to fall to the ground.
These can then be carried into higher levels of the atmosphere to freeze into chunks of ice, which fall as hail or big raindrops, they wrote.
There are plenty of sources for this disruptive smoke, they noted.
“Several hundred thousand deforestation and agricultural fires burn in Amazonia during the dry season each year, covering vast areas with dense smoke,” they wrote.