As large parts of the Amazon burn, weather experts are warning that rainfall is unlikely to put out the fires in the coming weeks. The Amazon is the world's largest rainforest. Brazil's National Space Research Institute reports that the number of fires has risen by 85 percent to more than 77,000 in the past year. That is the most since the research center began keeping records in 2013. The fires are not limited to Brazil. At least 10,000 square kilometers of land are burning in Bolivia, near its border with Brazil and Paraguay.
Brazil's government has sent troops and military airplanes as part of firefighting efforts. But they will only be able to put out smaller fires and help to prevent new fires, experts say. The larger fires can only be put out by heavy rain.
The rainy season in the Amazon usually begins in late September. It takes weeks to build to widespread heavy rains throughout the area. The little rain that will fall in the next 15 days will be in areas that need it the least, says Maria Silva Dias. She is a professor of atmospheric sciences at the University of Sao Paulo. "The whole area needs it to rain more...and this will only happen around October," she said.
Heavy rain has to fall in a short enough period to put out a fire. If there is little rainfall, the water changes from a liquid to a gas and rises in the air, Dias explained. She said it would take at least 20 millimeters of rain within 1 to 2 hours to put out a forest fire, with more required for the larger ones.
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