Geology Reference
In-Depth Information
even through parts of earth's interior — but they never leave the planet. (See Chapter 5
for a description of molecules.) The cycling of water among the atmosphere, oceans,
and
lithosphere
(the rocky surface of earth's crust; see Chapter 4) is called the
hydrologic
cycle.
The hydrologic cycle is the never-ending transformation of water into its different forms.
Figure 12-1 illustrates the various parts and processes of the hydrologic cycle, which I
describe in this section.
Driving the cycle with evaporation
When heated, water molecules transform from liquid to gas (water vapor or steam) in a
process called
evaporation.
You observe this transformation any time you boil water.
Figure 12-1:
Earth's
hydrologic cycle.
