Parima Forest Reserve, State of Roraima, Brazil, 2018

Over the Amazon rainforest, rare is the day when you can see a clear sheet of blue sky or a solid blanket of gray cloud. Rather cloud formations offer an ever-changing spectacle. This begins in the morning when warm moist air rises from the jungle and makes contact with minuscule particles which permit the vapor to condense into water droplets and become little clouds resembling cotton balls known locally as aru. As the day advances, they rise and join forces and, temperature and wind speed permitting, gather strength to become a storm cloud known as a cumulonimbus. This is quite the most dangerous meteorological formation, reaching several thousand meters into the sky, spewing out pieces of ice and winds of up to 200 kilometers per hour (125 miles per hour) at the same time as sending lightning, strong winds, and fierce precipitation toward the jungle. Such is its force that even large aircraft will do everything to avoid it, helicopters immediately look for a jungle clearing in order to land and riverboats hurriedly take shelter from the blinding rain.