If you’re lucky enough to live in a place where a turn of the faucet is all you need to call forth a steady stream of fresh water, this illustration from the U.S. Geological Survey may have you thanking your lucky stars next time you touch that tap.
Though our planet appears to be lush with H20, the larger bubble in the illustration represents all the water in the world, ninety-six percent of which is found in the oceans. The smaller bubble is freshwater but even most of that is unreachable for humans. Now, squint:
Do you notice that “tiny” bubble over Atlanta, Georgia? That one represents fresh water in all the lakes and rivers on the planet, and most of the water people and life of earth need every day comes from these surface-water sources. The volume of this sphere is about 22,339 mi3 (93,113 km3). The diameter of this sphere is about 34.9 miles (56.2 kilometers). Yes, Lake Michigan looks way bigger than this sphere, but you have to try to imagine a bubble almost 35 miles high—whereas the average depth of Lake Michigan is less than 300 feet (91 meters).
Well, thirty-five miles seems like a pretty comfortable bubble — unless you happen to be trapped in Atlanta without an umbrella — but it is a precious and delicate one nonetheless.
A new look at water.Author on Google+