They are immense masses of water vapor that, carried by air currents, travel across the sky and account for a large part of the rain that rolls in various parts of the world. The main flying river in Brazil rises in the Atlantic Ocean, pumps volume by incorporating the evaporation of the Amazon rainforest, hits the Andes and escapes towards the south of the country. “The water vapor that makes this journey is extremely important for rain in almost all of Brazil”, says agronomist Enéas Salati, from the University of São Paulo (USP). See below the impressive intricacies of this gigantic flying rapids.
flying rapids
Volume of water circulating through the sky is similar to the flow of the Amazon River
1. The flying river rises in the Atlantic Ocean. The water evaporates in the sea, near the equator, and reaches the Amazon rainforest pushed by the trade winds. This block of steam passes low: 80% of it flies at a maximum height of 3 kilometers
2. The flow of this aerial shower is around 200 million liters per second (similar to that of the Amazon River), making the Amazon one of the wettest regions on the planet, in addition to causing the rains that fall daily throughout the region
3. As it passes over the forest, the flying river practically doubles in volume. This is because, by absorbing more radiation from the Sun than the ocean itself, the forest works like a gigantic kettle, releasing steam with the transpiration of the trees and the evaporation of the tributaries that run through the soil.
4. In the west of the Amazon, the mass of moisture meets a barrier of mountains 4 kilometers high, the Andes mountain range, which works like a dam in the sky, containing the air current on this side
5th. Much of the steam is accumulated in the Andes itself, in the form of snow. When it melts, this water flows down the mountains, giving rise to streams that, in turn, will form the main rivers of the Amazon basin, such as the Amazon.
5b. Not all steam that encounters the Andes stays there. About 40% of this celestial waterfall heads south. The humidity passes through Rondônia, Mato Grosso, Mato Grosso do Sul and São Paulo, ending the trip in the north of Paraná, about six days later.
6th. As it flows in mighty veins towards the sea, much of the water from the flying rivers is absorbed by the forest. When they transpire, the trees then release this liquid in the form of vapour, closing the cycle that will again feed the current in the sky.
6b. Finally, the flying river falls in the form of rain. More than half of the precipitation in the Midwest and Southeast regions comes from aerial rivers in the Amazon. In addition to this main vein, another 20 currents cross the sky of the country, carrying a volume of water equivalent to 4 trillion water tanks of 1000 liters!
• To get an idea of the importance of the Andes, the Amazon rainforest emerged about 15 million years ago, right around the time the mountain range was formed
• Gerard Moss’ team has already made 12 “dives” into the flying rivers, collecting hundreds of water vapor samples
• In 2008, a flying river that arrived in the city of São Paulo transported 3.2 million liters (more than an Olympic swimming pool) of water per second
cloud chasers
Researchers “surf” air currents to study the phenomenon
Since 2008, a scientific project has been trying to get to know the flying rivers better. The leader of the research is Gerard Moss, a French naturalized Brazilian engineer and explorer. His job is to fly a single engine collecting water vapour. “While all pilots avoid clouds, I go straight for them,” he says. On his plane, Moss hunts for moisture using 16-inch tubes chilled to minus 70 degrees. At such a low temperature, any steam that enters the tube immediately turns into water. The drops are then stored for laboratory analysis.