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Water Cycle
2009-07-06 17:58:20

The water cycle (or hydrologic cycle) describes the continuous movement of water above, below, and on the planet. Since the water cycle is in fact a "cycle", there is no beginning or end. Water exists in three states: liquid, vapor, and ice. Although the balance of water on our planet is fairly constant, individual water molecules may come and go. The water cycle is driven by the sun. The sun...

Word of the Day
ecotone
  • A transitional zone between two communities containing the characteristic species of each.
The word 'ecotone' comes 'eco-' plus a Greek root meaning 'tension'.