Scientists cannot predict when an El Niño will begin. But once it does, forecasters are able to predict changes to weather patterns. What would be a predicted weather effect of an El Niño?

Question

A.  Drier and warmer in the southeastern U.S.

B.  Colder than normal across the northeastern United States.

C.  More rain in Peru and Ecuador.

D.  More rain in Indonesia and the Phillipines.



Clarify Question

· What is the key concept addressed by the question?

· What type of thinking is required?



Gather Content

· What do you already know about El Niño?

 

Choose Answer

· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?



  Reflect on Process

· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

C.  More rain in Peru and Ecuador.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses El Niño.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.

Gather Content
· What do you already know about El Niño?
        o Every two to seven years on an irregular and relatively unpredictable basis, the water along the Peru-Ecuador coastline becomes warm, and the primary productivity becomes unusually low. This is called El Niño.
        o Because of the low primary productivity, the ordinarily prolific fish populations weaken, and populations of seabirds and sea mammals that depend on the fish are stressed and plummet.
        o The cause of El Niño is a weakening of the east-to-west Trade Winds in the region. The Trade Winds ordinarily blow warm surface water to the west, away from the Peru–Ecuador coast. This thins the warm surface layer of water along the coast, so that deep water—cold but highly rich in nutrients—is drawn to the surface, leading to high primary production. Weakening of the Trade Winds allows the warm surface layer to become thicker. Upwelling continues, but under such circumstances it merely recirculates the thick warm surface layer, which is nutrient-depleted.
        o The weakening of the Trade Winds is actually part of a change in wind circulation patterns that recurs irregularly. One reason the Trade Winds blow east-to-west in ordinary times is that the surface waters in the western equatorial Pacific are warmer than those in the eastern equatorial Pacific; air rises from the warm western areas, creating low pressure at the surface there, and air blows out of the east into the low pressure. During an El Niño, the warmer the eastern ocean gets, the more similar it becomes to the western ocean, reducing the difference in pressure across the ocean. Thus, once the Trade Winds weaken a bit, the pressure difference that makes them blow is lessened, weakening the Trade Winds further.
        o One specific result of an El Niño is to shift the weather systems of the western Pacific Ocean 6000 km eastward. The tropical rainstorms that usually drench Indonesia and the Philippines occur when warm seawater abutting these islands causes the air above it to rise, cool, and condense its moisture into clouds. When the warm water moves east, so do the clouds, leaving the previously rainy areas in drought. Conversely, the western edge of Peru and Ecuador, which usually receives little precipitation, gets a soaking. In addition, the northern U.S. and Canada are warmer, and the southeastern U.S. is cooler and rainier.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o During an El Niño, topical rainstorms that usually drench Indonesia and thePhilippines move eastward instead and bring rain to Peru and Ecuador.

  Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that El Niño causes a reversal of weather patterns, bringing extra rain to the Americas?