's Guide to the TOEFL® Test Podcast

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Monday, April 10, 2006

TOEFL® Podcast #22

Atmospheric Science - El Niño

Script by Dr. Lucy Tse

Audio Index:
Slow dialog: 01:16
Explanations: 03:41
Fast dialog: 16:35
Questions: 18:04

We’ve been talking about weather phenomena this week, and one such phenomenon that affects this region of the country is El Niño. An El Niño occurs when there is a warming of the ocean surface along the South American coast. This warm water current is usually associated with atmospheric changes. As the warm air spreads toward the east, it takes along with it rain. This results in rainfall in areas that are normally dry.

We classify an occurrence as El Niño when the water temperature is greater than 0.5°C across the central tropical region of the Pacific Ocean for a period longer than five months.

So, how often do they occur? Generally speaking, we see El Niños every three to five years, although it may be as long as seven years between occurrences. We normally see these patterns in late December, hence the name “El Niño,” which means “the Christ child” in Spanish.

El Niño episodes in recent years have lasted no longer than a few weeks or a month. After this time, the weather patterns go back to normal. But, there have been some cases of it lasting longer--several months in fact--which can have serious effects on the economy, such as the local fishing trade and the international markets that rely on it.
Now, if you’ll turn to page 362 in your textbook, you’ll see a diagram