100 gallons of Water Added into Air Daily by 1 Big Tree

Trees, and all plants do to some extent, recycle some of the rainwater that falls on them rather than let it all flow away


The "Smoke" in Great Smokey Mountains National Park

Smokey Mountains National Park
Source - art.com

The Great Smokey Mountains contain over 187,000 acres of old growth forest - the largest such forest east of the Mississippi. It got its name because, from a distance, this forest-covered range appears to be exhaling plumes of smoke into the sky above it.
But this is not smoke. This forest is usually covered in a mist that is the result of water vapor transpired by the trees and the natural fog created by water-laden air from the Gulf of Mexico that cools rapidly as it moves onto the higher elevations of the Appalachian mountain range.
Scientists estimate that a quarter of the rain that falls on these trees is transpired back into the atmosphere by the forest.


The Amazon Rain Forest

The Amazon Rain Forest
Source - travelblog.com

Trees in the 55 million year-old Amazon Rain Forest cover over 1.4 billion acres.
The forest gets about 9 feet of rain every year.
Scientists estimate that fully half the rainfall is transpired back into the atmosphere by trees of the rain forest. 
Estimates vary widely, but every canopy tree in the rain forest is estimated to transpires more than 00 gallons of water every day, during the growing season - this translates into adding over 10,000 gallons of water transpired into the atmosphere over the course of a summer from ONE tree.

Trees are Tall Because Water Can Move Against Gravity

Source - USDA Forest Service

The Sequoia Sempervirens (commonly known as The California Redwood) tree species has the tallest tree in the world, reaching a height of 379.1 feet. This height, a bit short of the estimated 430 feet maximum possible height for a tree, is the result of the tree's ability to develop an internal structure that water can use to rise from tree roots to the topmost leaves of the tree.


Water Molecule

Source- H2O_molecule_scheme_of_dipole.png‎

The unique shape of the water molecule, the shape that makes the water molecule a "polar" molecule, is used by the tree to design its internal water supply system that moves water up the tree. Simply speaking, water moves up the tree because it is "attracted" to the sides of the channels that the tree has created in its internal structure.


Capillary Action

Source - davidnelson.md.

Capillary action is the phenomenon that raises water molecules closest to a vertical surface (of the sides of a tube) because the attraction between the water molecules and the surface material molecules is high and the tube is so small that the water in the tube is unable to form a water surface, as shown on the right. 
When there is a very very tiny or no water surface, then the condition exists (called Capillary action) that all the water  molecules on the surface are "pulled up" and water rises against gravity.
Water in a narrow tube continues to rise due to capillary action, till the forces of attraction (between the water molecules and molecules of the wall material) are able to support the column of water that is formed in the tube. Measurement of this attraction force and calculations of water weight have shown that the maximum height that capillary action can transport water, against the force of gravity, is about 430 feet. So no tree can be taller than 430 feet in height. 


Capillary action is also behind the ability of water to move through soil from high humidity locations to low humidity locations.


Tree Leaves & Branches Are Smallest at the top

Source-hollowcreektreefarm.com

In especially tall trees, the number of branches, the length of a branch, the number of leaves and the size of a leaf all reduce as the height increases. 
These differences with height are due to the amount of water that the tree has available at different heights. As less water is available at greater heights, there is less need for longer branches, lots of leaves and leaves of larger sizes, because transpiration needs are less at greater heights. 
This reducing volume of water with height, produces the typical conical shape of trees.