| 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 and in the animation above.
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.
From NASA: http://kids.earth.nasa.gov/archive/nino/intro.html |
