is constantly moving within and around the earth in a continuous
pattern called the hydrologic cycle.
with Water Use the navigation buttons on the right
to explore the water cycle. Using the oval buttons, you can
see the three primary stages of the water cycle in action.
Then check out the processes that make up these stages by
using the rectangular buttons.
such rivers as the Mississippi River may seem huge to us,
they are a very small part of the entire hydrologic cycle.
Note that only about 0.2% of the water is located in rivers,
lakes, or the atmosphere.
supply of water remains constant, however, people can effect
the quantity and quality available. Large cities accelerate
water drainage rates through road drains and city sewer systems.
This changes the rates of infiltration, evaporation, and transpiration
that would normally occur.
suns energy heats up water from oceans, lakes, ponds,
rivers and causes it to evaporate. In addition, water absorbed
by plants pass through them and then transpires through the
leaves to the air and changes it into water vapor. The water
vapor rises then cools and condenses to form clouds.
Clouds hold the water temporarily as vapor, small liquid droplets,
or little ice particles. When cloud temperatures become cold
enough, moisture vapor cools and condenses.
condensed water within clouds forms larger liquid drops or
solid moisture particles and is pulled to earth by gravity
as precipitation in the form of rain or snow. Some of this
rain or snow is absorbed by the ground (infiltration) and
then becomes groundwater (0.6%). Most of this water return
to the ocean. Some water runs off the surface of the ground
and becomes nonpoint runoff to streams and rivers, finally
returning to the ocean. A very small amount (2%) of the precipitation
falls in colder areas of the earth as snow and becomes tied
up for longer periods of time in glaciers and ice caps.