Half the Amazon's Rain Was Breathed Out by Trees That Morning
More water passes via tree leaves than runs in every river and creek worldwide combined.
The joe gardener Show - Organic Gardening - Vegetable Gardening - Expert Garden Advice From Joe Lamp'l · 490-How Leaves Conjure Up Our WorldRoughly half the rain falling in the Amazon was breathed out by trees that same morning, says evolutionary biologist Jonathan Silvertown.
Each leaf pulls water up from the soil and releases it through tiny pores as vapor, and a whole forest does it at staggering scale. More water travels via tree leaves than runs in every river and creek worldwide combined.
Forests send much of that water back into the air, recycling moisture into downwind clouds and rain. Where trees are cleared, rainfall usually drops and becomes more erratic.
Questions people ask
How does a tree lift water all the way to its top leaves?
It does not pump it the way an animal heart would. Water evaporating from leaves creates suction that pulls the column of water up from the roots, helped by water molecules sticking to each other and to the walls of tiny tubes in the wood. Sunlight powers the evaporation, so the taller the tree and the stronger the sun, the stronger the pull.
Does this forest-made rain happen outside the Amazon?
Yes, though the Amazon is the most dramatic example. Large forests in the Congo Basin and Southeast Asia also recycle huge amounts of moisture back into the air, seeding downwind clouds and rain. Even smaller forests raise local humidity and cool the air enough to make nearby showers more likely.
If trees are cut down, does the rain really stop?
Rainfall usually drops and becomes more erratic. Without leaves returning moisture to the air, clouds form less reliably and more incoming rain runs off instead of being recycled. Scientists have linked Amazon deforestation to longer dry seasons and reduced rainfall downwind of cleared areas.