During the fall in the Northern Hemisphere, the winds which are blowing
from east to west, (NORTHEAST TRADE WINDS), from the equator to about 30
degrees north latitude, in the Southern Hemisphere, the (SOUTHEAST TRADE
WINDS), from the equator to about 30 degrees south latitude, become weak
and by Christmas time are reversed, these winds and now blowing west to east,
from the area of Australia and Indonesia towards South America, or
from high pressure over the western tropical Pacific towards lower pressure
over the eastern tropical Pacific.
The winds blowing from west to east move the warm waters eastward, when
this occurs, The UPWELLING of the colder water rich in nutrients from
the depths of the Pacific Ocean weakens, or does not occur at all. This
lack of UPWELLING of colder water rich in nutrients causes a lack of food
for the fish and sea life in the area, thus the fish, seabirds and other
animal and wildlife which the phytoplankton and fish help support in the
food chain, migrate away from the area. Some sea life normally found in
these tropical waters migrate as far north to off the western coast of the
United States.
As the warm water moves eastward, it strikes the western coast of
South America, and then spreads out, when this happens, the sea level in the
eastern Pacific along the coasts of Ecuador and Peru rise about 1 foot,
likewise, the sea levels in the western Pacific lower by about a foot,
exposing and destroying any exposed coral reefs of the many islands in the
Pacific. These warm waters spread south along the shores of South America
and northward to off the western coast of the United States, and as far
north as Canada. Ocean water temperature at the surface rise over 10
degrees from normal levels of 70 Degs. F. to well into the 80s.
In the future look for weather articles on: Hurricanes. Tornadoes.
Floods. Thunderstorms. Winds. Radar. Atmosphere. Orographic Lifting.
Adiabatic Process. Clouds. Relative Humidity. Water. Temperature and
Temperature Scales, and many more.
The phenomenon of EL-Niño has been going on for millions of years.
Since it occurs around Christmas time, it was given the name Christ Child
by the Peruvian fishermen some 4 centuries ago. It is only in the past 10
to 20 years that we have become alert to what its world wide effects are.
Through research it has been learned that an El-Niño occurs about every 3
to 7 years and no two events are alike.
The last major El-Niño occurred in 1982-1983. At that time it was still not
understood about its world wide effects. So as not to be caught off guard
again, the documentation and analysis of past and present weather,
and weather related events are being conducted.
Currently observations are carried on by ships, weather satellites,
space shuttle, land and sea based stations in the Pacific as well as
thousands of weather stations through-out the world.
Many buoys containing weather instruments and other electronic devices
have been deployed in the Pacific from Mexico to South America and along
the equator to Indonesia and Australia. These observe and record information
about the atmosphere and ocean water. The information is relayed via
satellite to weather centers around the world for analysis.
The Effects of El-Niño are strongest during the winter in the Northern
Hemisphere, summer in the Southern Hemisphere. Winters are milder
over portions of Western Canada, and the northern portions of the United
States. Heavy rains and severe weather occur more frequently over the
southern United States.
The northern polar jet stream associated with the polar front is a steering
mechanism in the atmosphere. It forms a boundary between the cold dry air
to the north and warm moist air to the south and is usually located over
the central and southern United States during the winter months. During an
El-Niño, the polar jet stream becomes situated further north along the
U.S./Canadian border, in a somewhat west to east position. This position
creates a blocking action of the cold air masses which are moving south from
the interior of Canada and the Arctic regions, allowing warm moist air from
the tropics to penetrate farther north than usual.
Another jet steam which is called the southern jet stream is usually located
at 15-20 degrees north latitude. During El-Niño this jet shifts north over
the southern United States to 30-35 degrees north latitude.
"Weather By Giannetta"
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