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Climatologists believe they know why Earth has undergone a

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YashYashkratos

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17 Jan 2024, 03:26

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Great Question

A) strengthens - shows the time period observation was correct.

B) strengthens - shows existence of such clouds

C) strengthens - shows relation between dust and earth's temp

D) irrelevant- correct option

E) strengthens- shows relation between debris and ice age occurrence

MohdZaidKhan

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21 Oct 2024, 21:43

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vjsharma25

Climatologists believe they know why Earth has undergone a regular sequence of ice ages beginning around 800,000 years ago. Calculations show that Earth’s orbit around the Sun has fluctuations that coincide with the ice-age cycles. The climatologists hypothesize that when the fluctuations occur, Earth passes through clouds of cosmic dust that enters the atmosphere; the cosmic dust thereby dims the Sun, resulting in an ice age. They concede, however, that though cosmic dust clouds are common, the clouds would have to be particularly dense in order to have this effect.

Each of the following, if true, would lend support to the climatologists’ hypothesis EXCEPT:

(A) Earth did not pass through clouds of cosmic dust earlier than 800,000 years ago.
(B) Two large asteroids collided 800,000 years ago, producing a tremendous amount of dense cosmic dust that continues to orbit the Sun.
(C) Earth’s average temperature drops slightly shortly after volcanic eruptions spew large amounts of dust into Earth’s atmosphere.
(D) Large bits of cosmic rock periodically enter Earth’s atmosphere, raising large amounts of dust from Earth’s surface.
(E) Rare trace elements known to be prevalent in cosmic debris have been discovered in layers of sediment whose ages correspond very closely to the occurrence of ice ages.

Source : LSAT PrepTest 44, Q17

the conclusion is , Orbit fluctuation->cosmic dust cloud enters atmosphere -> dense dust cloud block sun->temp of earth drops.

A-strenghtening .
B-strenghteninng : orbit fluctuations therefore cause cosmic dust cloud to enter atmosphere .
C-strengthening - so dust thus HAS an effect on temperature . that means theory of dust cloud blocking sun and temp rise might be true .
D-dust is discussed but no other parameter is discussed to have a correlation . Answer
E-strenghtening -cosmic debris is found in earth's soil dated same as ice age ...

gurugmat

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22 Oct 2024, 03:02

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Answer choice (D) states, "Large bits of cosmic rock periodically enter Earth’s atmosphere, raising large amounts of dust from Earth’s surface." While this describes a source of dust in Earth’s atmosphere, this dust is not of cosmic origin, but rather raised from Earth’s surface itself. The hypothesis specifically involves cosmic dust dimming the Sun by coming from space. Dust raised from Earth’s surface does not align with this core premise, as it would not dim the Sun in the way required to trigger an ice age.

MohdZaidKhan

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22 Oct 2024, 03:06

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gurugmat

But it does shakes the asumption involved in main conclusion that dust do have an effect in lowering temp .

gurugmat

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22 Oct 2024, 03:16

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The climatologists’ hypothesis is about a dust cloud that enters the Earth’s atmosphere, not a dust
cloud within the Earth’s atmosphere. Hope this helps.

MohdZaidKhan

gurugmat

But it does shakes the asumption involved in main conclusion that dust do have an effect in lowering temp .

saurabhmishrano1

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To identify the correct answer, we need to find the choice that does not support the hypothesis that Earth's ice ages are caused by dense clouds of cosmic dust dimming the Sun. The correct option will either be irrelevant to the hypothesis or contradict it.

Evaluating the Options:

(A) Earth did not pass through clouds of cosmic dust earlier than 800,000 years ago.

This supports the hypothesis because it aligns with the timing of ice ages beginning 800,000 years ago. If no clouds existed before this time, it supports the idea that cosmic dust clouds are responsible.

(B) Two large asteroids collided 800,000 years ago, producing a tremendous amount of dense cosmic dust that continues to orbit the Sun.

This directly supports the hypothesis by providing a plausible source for the dense clouds of cosmic dust that coincide with the start of ice ages.

(C) Earth’s average temperature drops slightly shortly after volcanic eruptions spew large amounts of dust into Earth’s atmosphere.

This supports the hypothesis indirectly by establishing a parallel: dust in the atmosphere (in this case from volcanoes) causes a cooling effect, similar to what cosmic dust clouds would do.

(D) Large bits of cosmic rock periodically enter Earth’s atmosphere, raising large amounts of dust from Earth’s surface.

This does not directly support the hypothesis. The hypothesis depends on cosmic dust clouds in space dimming the Sun, not on dust raised from Earth’s surface by cosmic rock impacts. This is unrelated or minimally relevant to the hypothesis.

(E) Rare trace elements known to be prevalent in cosmic debris have been discovered in layers of sediment whose ages correspond very closely to the occurrence of ice ages.

This supports the hypothesis by providing physical evidence of cosmic debris coinciding with ice ages, linking cosmic events to climatic changes.

Correct Answer: (D)
This is the only option that does not directly support or strengthen the hypothesis regarding cosmic dust clouds dimming the Sun and causing ice ages. It describes a phenomenon unrelated to the hypothesis.