Over a course of a single growing season, forests pump millions of gallons of water into the air. This is why walking through a forest on a hot summer day is so refreshing. Even a single tree pumps dozens of gallons of water from its roots to its leaves each day.
How is this possible?
The hot sun on the leaves causes water to evaporate from the leaves. This evaporating water creates a vacuum within the leaves’ cells. Because water molecules like to “stick together”, this vacuum pulls the water far up into a tree – almost like it is being sucked up a drinking straw. Water molecules have been tracked moving as fast as 25 miles per hour up through the trunk of a tree!
Over 90% of the water which moves from the ground into the leaves of a tree is evaporated from the surface of the leaves. Only 2% of the water is used for photosynthesis. It is this massive amount of evaporation that provides the driving force to suck so much water out of the ground and carry it hundreds of feet into the air. Even a small grove of trees removes tons of water from the soil and releases it into the air each day.
It has been estimated that an apple tree gives off 16,000 pounds of water to the air during one growing season. This is an amazing system involving capillary flow, hydrogen bonding of water molecules, osmosis, and vacuum pressure.
Trees are God’s method of humidifying the world. And all this happens in total silence! What an example of God’s engineering excellence.1
For he makes his sun rise on the evil and on the good, and sends rain on the just and on the unjust.Matthew 5:45
References and Notes
- Inspired Evidence: Only One Reality, Bruce Malone, Julie VonVett