The Amazon is the world’s largest tropical forest, home to unmatched biodiversity and one of the planet’s longest rivers. Besides the Amazon River, the Amazon rainforest also features “flying rivers:” invisible streams of vapour that travel through the atmosphere, fuelling rainfall both within the forest and far beyond its boundaries.
The forests play a central role in this system. Much of the moisture that rises into the atmosphere comes from transpiration. Trees pull water from the soil through their roots, transport it to the leaves and release it as vapour. That vapour becomes rainfall — sometimes locally, sometimes hundreds of kilometres away.
In the dry season when rain is scarce, up to 70 per cent of rainfall in the Amazon comes from this moisture-recycling generated by the forest itself. This raises a key question: where do the trees find the water to keep the cycle going during the driest months?
