Hi everyone,
Got 5/7 correct in 15:20 minutes, including 5:10 minutes to read.
Tough passage indeed. What helped me here was to visualize the geographies, the direction of winds and waves.
---------------------------------------------------------------------------------------------------------P1In the first paragraph we are presented with a model that might explain the appearance of a phenomenon: El NINO. Researchers are enthusiast because such models try to correlate wind and warm/cold ocean temperatures that are typical of El NINO and its opposite ANTI EL NINO. The author then proceeds by claiming that without developing such models it is impossible to confirm such correlation and if the hypothesis upon which the model lies is true, then the answer to our questions lie in the Ocean.
Purpose: To present a model and to clarify its scope.
P2In this paragraph the author presents 2 conditions typical of EL NINO: 1 warm water in the east side and winds coming from the west. Then the author proceeds by detailing where in all this situation the model previously discussed comes into play. The model claims that such wind generates a signal directed to the ocean in the west side. Such signal is represented by a Wave (Called Rossby
negative) that we know travels to the west side in a way that is parallel to the equator, encountering islands such as Philippines and Indonesia.
Purpose: To present 2 key conditions of EL NINO and
to detail the correlation proposed by the model discussed in the first paragraph
P3In paragraph 3 the author keeps explaining the travel made by the Rossby negative waves. When such waves arrive on the west side they turn into small Kelvin negative waves that go into the opposite direction, that is eastward. Then the author proceeds by explaining how these Neg Kelvin waves reverse the effect done in the east side by the winds and warm water. Thanks to the negative Kelvin water will get colder and an ANTI EL NINO probably will develop. Now
positive Rossby waves will start their journey westward and they will produce positive kelvin waves that will reverse the conditions again. Clearly this is a cycle.
Purpose: To keep explaining the cycle
Main pointTo explain the cycle that produces EL NINO and ANTI EL NINO in light of a new mathematical model
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1. The primary function of the passage as a whole is to
Pre-thinking
Main point question
To explain the cycle that produces EL NINO and ANTI EL NINO in light of a new mathematical model
(A) introduce a new explanation of a physical phenomenon
(B) explain the difference between two related physical phenomena
(C) illustrate the limitations of applying mathematics to complicated physical phenomena
(D) indicate the direction that research into a particular physical phenomenon should take
(E) clarify the differences between an old explanation of a physical phenomenon and a new model of it No differences mentioned
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2. Which of the following best describes the organization of the first paragraph?
Pre-thinking
Structure question
To present a model and to clarify its scope.
(A) A theory is presented and criticized.
No theory but a model. Plus no criticism
(B) A model is described and evaluated.
The author does not expresses an opinion about the model (Good versus bad)
(C) A result is reported and its importance explained.
A result sounds a little bit awkward but it matches with the term prediction used in the first line.
(D) A phenomenon is noted and its significance debated.
the focus of P1 is not EL NINO but the model
(E) A hypothesis is introduced and contrary evidence presented.
no contrary evidence
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3. According to the passage, which of the following features is characteristic of an El Nino?
Pre-thinking
Detail question
From P2: and (2) winds blow from the west into the warmer
TIP: when we are 100% about a detail we found, there is no need to read option C,D and E.
(A) Cold coastal water near Peru
(B) Winds blowing from the west
(C) Random occurrence
(D) Worldwide effects
(E) Short duration
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4. According to the model presented in the passage, which of the following normally signals the disappearance of an El Nino?
Pre-thinking
Detail question
We can find this answer in P3: my guess now it is that the arrival of negative kelvin waves to the east side would be a strong signal
(A) The arrival in the eastern Pacific of negative sea-level Kelvin waves
(B) A shift in the direction of the winds produced by the start of an anti-El Nino elsewhere in the Pacific
no shift mentioned
(C) The reflection of Kelvin waves after they reach the eastern boundary of the Pacific, along Ecuador and Peru
out of scope
(D) An increase in the speed at which negative Rossby waves cross the Pacific
increases in speed of Rossby waves are not discussed
(E) The creation of a reservoir of colder, deep ocean water trapped under the pile of warmer, surface ocean water
Opposite
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5. It can be inferred from the passage that which of the following would result fairly immediately from the cessation of the winds of an EI Nino?
Pre-thinking
Inference question
IMO
1: cold water
2: positive Rossby wave
3: Positive Kelvin wave
I. Negative Rossby waves would cease to be generated in the eastern Pacific.
In line with number 2
II. The sea level in the eastern Pacific would fall.
Yes, when El NINO is at play the sea levels in the east side get higher and when ANTI EL NINO begins water levels will decrease
III. The surface water in the eastern Pacific would again be cooled by being mixed with deep water.
In line with point 1
(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) I, II, and III
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6. Which of the following, if true, would most seriously undermine the validity of the model of EI Nino,that is presented in the passage?
Pre-thinking
Weaken question
We have multiples way to weaken an entire passage, so it makes sense to evaluate the options
(A) During some years EI Nino extends significantly farther along the coasts of Ecuador and Peru than during other years.
no impact
(B) During periods of unusually cool temperatures along the eastern Pacific, an EI Nino is much colder than normal.
No impact
(C) The normal upwelling of cold water in the eastern Pacific depends much more on the local characteristics of the ocean than on atmospheri.c conditions.
No impact
(D) The variations in the time it takes Rossby waves to cross the Pacific depend on the power of the winds that the waves encounter.
Plausible and no impact
(E) The western boundary of the Pacific basin is so irregular that it impedes most coastal Kelvin waves from beading eastward.
Correct, if Kelvin waves cannot reach the east side, then the cycle stops and we would never see again EL NINO and ANTI EL NINO
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7. The passage best supports the conclusion that during an anti-EI Nino the fastest-moving signal waves are
Pre-thinking
Inference question
We do not have explicit comparisons but we have a couple of data. From P3: These eventually shoot toward the equator, and then head eastward along the equator propelled by the rotation of the Earth at a speed of about 250 kilometers per dc1y.
This speed is the highest mentioned in the passage so we can infer that Kelvin waves heading to east are the fastest.
What could be confusing about option E is the usage of Positive since the passage talks about negative kelvin waves. From a deeper understanding we will know that we are dealing with a cycle and so negative and positive kelvin waves will travel eastward.
(A) negative Rossby waves moving east along the equator
(B) positive Rossby waves moving west along the equator
(C) negative Kelvin waves moving west along the equator
(D) positive Kelvin waves moving west along the equator
(E) positive Kelvin waves moving east along the equator
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