|El Nino Conditions|
Now that you are very well aware of what normal conditions in the
Pacific are, we can now explain what happens during an El Niņo. If you still unsure about
some of the normal conditions, please go back to the previous
The strength of the Trade Winds declines - The strength of the trade winds declines which then reduces the force that the winds are blowing from east to west (thanks to Sun Sentinel)
As we have previously stated, El Niņo have a frequency of about three to five years. Even though scientists do not know the exact workings of an El Niņo, they do have a pretty good idea of what occurs.
At one point, when the air pressure gradient declines as part of the southern oscillation, the southeast trades weaken. Slackening trade winds allow the warm surface water that had been driven westward to drift slowly eastward along the equator and then southward off the Peruvian coast. El Niņo is in progress.
During an intense El Niņo, the southeast trade winds eventually shift direction and become equatorial westerly. This phenomenon is technically knows as El Niņo-Southern Oscillation or ENSO, but many people refer to it as simply El Niņo.
Upwelling Decreases Strength - Upwelling, which was such a strong force during normal conditions, now loses strength and the great temperature difference is not more (thanks to Sun Sentinel)
The warm water near the South America coast is no longer warm because
upwelling has decreased. Because of this, the water now increases its temperature by
3.5-5.5o F. This has fatal effects on the living organisms in the food chain
since less less nutrient rich water is now brought to the surface. Planktons are decreased
in numbers, thus, bringing the rest of the food chain down with them.
Deprivied of nutrients, plankton in the coastal waters of the south-eastern Pacific began to die. Their population collapse affects the open-ocean [pelagic] fish that feed on them and that are the basis of the fishing industries of Ecuador, Peru, and Chile. The fish shoals move in search of more nutritious waters. Their location is upredictable and often cut out of range of the fishing vessels. Cathces usually drop while El Niņo conditions previal.
Go to our impacts section to learn more about this and other effects of
Warm air creates clouds beginning the wet season - The warm water in the west becomes water vapor which rises and then condenses and form clouds (thanks to Sun Sentinel)
In normal conditions, rain clouds used to be over Australia. However,
now they move towards the coast of South America bringing heavy rains and floods to Peru
and Ecuador. This movement also has potential to bring drought to Australia. The
equatorial trade winds now decrease greatly in strength and the winds to the west now
start to change direction. Then begin to blow the opposite way and these winds start to
become stronger than the trade winds.