El Nino - and What is the
Southern Oscillation Anyway?!
El Nino, an abnormal warming of surface ocean waters in the eastern tropical Pacific, is one part of
what's called the Southern Oscillation. The Southern Oscillation is the see-saw pattern of
reversing surface air pressure between the eastern and western tropical Pacific; when the surface pressure is
high in the eastern tropical Pacific it is low in the western tropical Pacific, and vice-versa. Because the
ocean warming and pressure reversals are, for the most part, simultaneous, scientists call this
phenomenon the El Nino/Southern Oscillation or ENSO for short. South American fisherman have
given this phenomenon the name El Nino, which is Spanish for "The Christ Child," because it comes
about the time of the celebration of the birth of the Christ Child-Christmas.
To really understand the effects of an El Nino event,
compare the normal conditions of the Pacific region
and then see what happens during El Nino below.
Normal Conditions (Non El Nino)
El Nino Conditions
Scientists do not really understand how El Nino
forms. It is believed that El Nino may have contributed to the 1993 Mississippi and 1995
California floods, drought conditions in South America, Africa and Australia. It is also believed that
El Nino contributed to the lack of serious storms such as hurricanes in the North Atlantic which spared states
like Florida from serious storm related damage.
Unfortunately not all El Nino's are the same nor does
the atmosphere always react in the same way from one El Nino to another. This is why NASA's Earth
scientists continue to take part in international efforts to understand El Nino events. Hopefully one day
scientists will be able to provide sufficient warning so
that we can be better prepared to deal with the damages and changes that El Nino causes in the
weather.
Click here
to learn more on Normal Conditions (Non El
Nino)
or here
to learn more on El Nino Conditions. |
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