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Chapter 13
Section 1: Atmosphere and
Climate Change
Terms

Weather: state of the atmosphere at a
particular place at a particular moment.

Climate: long-term prevailing weather
conditions at a particular place based
upon records taken.
What Factors Determine Climate?
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Latitude
Atmospheric circulation
patterns
Oceanic Circulation
patterns
Local geography of an
area
Solar activity
Volcanic Activity
Distance from the equator
Latitude

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Distance from the
equator measured in
degrees north or
south of the equator.
Low latitudes:
temperatures high
year-round. No
summers or winters.
High latitudes: yearly
temperature range is
larger.
Atmospheric Circulation
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Cold air sinks
As cold air sinks, it
compresses and
warms.
Warm air rises,
expands and cools.
Solar energy heats the ground, which
warms the air above it.
 This warm air rises, and cooler air moves
in to replace it. (WIND)
 Circulation pattern determines
precipitation pattern.
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Areas near equator are warmer, warm air
holds more water. As water cools, it cannot
hold as much water—this leads to rain.
Global Circulation Patterns
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Cool air over the equator is forced toward the
poles.

Cold, dry air descends at the poles, which are
essentially very cold deserts.
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Coriolis Effect – air defected from its path due to
earth’s rotation
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/gifs/coriolis.mov
Three Prevailing Winds
Due to Coriolis
Effect
Polar
easterlies
 Westerlies
 Trade Winds
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Prevailing Winds
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Prevailing winds: winds that blow
predominantly in one direction throughout
the year.
Trade winds: Blow from the northeast in the
Northern hemisphere and the southeast in the
Southern hemisphere. Near the equator.
 Westerly's: northwest winds in Northern
hemisphere, and southwest winds in the
Southern hemisphere. 30-60o latitude
 Easterlies: cold dry air – cold deserts

Oceanic Circulation Patterns

Surface currents affect the
climate in many parts of the
world.
El Niňo: Pacific ocean is
warmer than usual. Causes
increased rainfall in some areas
and droughts in others.
 La Niňa: (opposite) Pacific is
cooler than usual.
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Topography

Mountains trap clouds, which can cause
rain on one side and dry air and climate on
the other.
Other Influences on Earth’s Climate
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Sun: Increased UV
rays = increased
ozone = warmer
atmosphere.
Volcanic eruptions:
sulfur dioxide
released reflects
sunlight and causes
global temp. to
decrease.
Seasonal Changes in Climate

Seasons change as a
result of the earth’s tilt
on its axis.

Northern hemisphere
tilts toward sun in
summer and away from
it during winter.