Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go in a hurry. The water in the apple you ate yesterday may contain molecules that fell as rain half-way around the world last year or was drunk by a dinosaur 100 million years ago.
Earth's water supplyIn all, the Earth's water content is about 1.39 billion cubic km (331 million cubic miles) and the vast bulk of it, about 96.5%, is in the global oceans. Approximately 1.7% is stored in the polar icecaps, glaciers, and permanent snow, and another 1.7% is stored in groundwater, lakes, rivers, streams, and soil. Finally, a thousandth of 1% exists as water vapor in the Earth's atmosphere.
Related category• ECOLOGY AND THE ENVIRONMENT
Home • About • Copyright © The Worlds of David Darling • Encyclopedia of Science • Contact