Geoscience Reference
In-Depth Information
El Niño
To investigate El Niño more thoroughly, go to the
Geo Media
Library
and select
El Niño
. This animation has four parts that
demonstrate how the patterns evolve, recover, and impact the
coast of Peru. Once you complete the animation, be sure to an-
swer the questions at the end of the module to test your under-
standing of this concept.
South America (and even the southwestern United States) and
drought to the western Pacific. This weather reversal occurs
because the atmospheric pressure in the eastern Pacific is rela-
tively low, whereas it is relatively high in the western Pacific.
Remember that air flows from areas of high pressure to low
pressure, which, in this case, pushes the warm surface waters
to the east side of the Pacific.
2.
Like that of the atmosphere, the primary consequence
of oceanic circulation is to redistribute heat energy
around Earth.
3.
Warm, generally low-salinity currents flow along the top
of the oceans. In contrast, cooler, saltier water flows at
great depths.
4.
Normal equatorial circulation in the Pacific is easterly,
resulting in extremely warm waters in the western
Pacific and upwelling cold waters in the eastern part of
the basin. This normal pattern causes precipitation in
the west and dry conditions in the east.
KEY CONCEPTS TO REMEMBER ABOUT
OCEANIC CIRCULATION
1.
Oceanic circulation is driven by winds and generally
flows in the same direction as atmospheric circulation.
Due to the presence of the continents, however, distinct
circulatory cells, or gyres, exist in the oceans.
5.
An El Niño occurs when the normal (equatorial) circu-
latory system in the Pacific is reversed. This reversal
results in drought in the western Pacific and strong
storms in the eastern Pacific.
S U M M A R y O F K E y C O N C E P T S
1.
Air pressure refers to the weight of air distributed on
the surface of Earth. The two basic kinds of pressure
systems are high (anticyclones) and low (cyclones).
High-pressure systems in the Northern Hemisphere are
columns of air that rotate clockwise and descend to-
ward the surface of Earth within their core. In contrast,
low-pressure systems in the Northern Hemisphere are
columns of air that lift from the Earth's surface within
their core as they rotate counterclockwise. The rotation
of these respective systems is opposite in the Southern
Hemisphere.
a spiral motion of air in both low- and high-pressure
systems.
3.
The global circulatory system consists of a series of
separate, but connected, pressure systems that distrib-
ute air around Earth. Humans are now trying to harness
this energy source in a systematic way to supplement
current energy supplies.
4.
In addition to large-scale wind systems, several region-
al and local-scale circulation systems occur, including
monsoon winds, land-sea breezes, katabatic winds, and
Chinook/foehn winds.
2.
The speed and direction of airflow depend on many vari-
ables. The pressure gradient force refers to the differ-
ence in air pressure that exists between adjacent areas.
The Coriolis force refers to the deflection that occurs in
winds due to the rotation of Earth on its axis. Features
on the Earth's surface, such as mountains, forests, and
buildings, create a frictional force that acts opposite to
the wind's direction. The combined effect of the pressure
gradient force, Coriolis force, and frictional force causes
5.
Oceanic circulation is driven by winds and generally
flows in the same direction as atmospheric circulation.
Due to the presence of the continents, however, distinct
circulatory cells, or gyres, exist in the oceans.
6.
An El Niño occurs when the normal (equatorial) circula-
tory system in the Pacific is reversed. This reversal re-
sults in drought in the western Pacific and strong storms
in the eastern Pacific.
