The
atmosphere covers the Earth. It is a thin layer of mixed gases which
make up the air we breathe. This thin layer also helps the Earth from
becoming too hot or too cold, much like clothing does for us. Weather
systems, which develop in the lower atmosphere, are driven by heat
from the sun, the rotation of the Earth, and variations in the Earth's
surface.
Oceans
cover about 70 percent of Earth's surface. Their large mass and
thermal
properties, enable them to store vast quantities of heat. Oceans
buffer and regulate temperature energy absorbed or lost by
the oceans results in a smaller surface temperature change than
would occur over land. The atmosphere and ocean constantly exchange
energy and matter. For example, water evaporates from the oceans
into the atmosphere. This moisture then falls back to the Earth
as precipitation
rain, snow, sleet, and even the morning dew on the grass.
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Land
covers 27 percent of Earth's surface, and land topography
influences weather patterns. For example, the weather in areas covered
by mountains can be completely different than the weather in areas
where the land is mostly flat.
Ice
is the world's largest supply of freshwater. It covers the remaining
3 percent of Earth's surface including most of Antarctica and Greenland.
Because ice is highly reflective and because of its insulating properties,
ice plays an important role in regulating climate.
The
biosphere is that part of Earth's atmosphere, land, oceans that
supports any living plant, animal, or organism. It is the place
where plants and animals, including humans, live. Large quantities
of carbon dioxide are exchanged between the land-based biosphere
and the atmosphere as plants take in carbon dioxide and give off
oxygen, and animals inhale oxygen and exhale carbon dioxide.
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