Science: El Niño

The El Niño weather disturbance happens about 30 times per century, taking place in the South Pacific. They affect weather around the globe. But to understand El Niño we must first know the normal weather patterns in the South Pacific.

• Normally, a low pressure system in the southwest Pacific draws air from a high pressure system the southeast Pacific creating southeast trade winds. These pressure systems are caused by warm air rising the west, moving east and descending over South America. The low pressure systems near Australia and Oceania create rainy conditions.

• The trade winds create the South Equatorial Current, which move warm surface water westward where it pools near Australia and Oceania.

• As the surface water is blown away from from South America cold nutrient rich water rises from the deep to take its place. This nutrient rich water supports a food chain and a local fishing economy.

But, during an El Niño year, for reasons still unknown, the cycle slows or even reverses. (See diagram above.)

El Niño causes floods, droughts and storms around the world.

Note: El Niño is a complex but interesting subject, I do recommend doing more research.

Sources:
Book: Ocean by The American Museum of Natural History.
Book: Oceans: A Visual Guide by Stephen Hutchinson and Lawrence E. Hawkins

Diagram: Mark Dowe's Journal