PrepTest 147, Section 1, Question 10

What we’re looking for

Working the answers

• A

  This says cold air is required to form the clouds that produce snow. The argument is about what happens to atmospheric temperature when snow and ice cover more of the surface. Explaining a condition needed for snow to form doesn't establish that snow then helps cool the atmosphere. Also, being required for snow doesn't mean cold air always produces snow.

• B

  Other influences on temperature can exist alongside the effect described here. The author doesn't claim that reflectivity is the only factor. This answer doesn't tell us whether those other factors reinforce, offset, or leave unchanged the proposed cooling effect, so it doesn't add support for that effect.

• C
  Correct

  This adds a way that the uncovered surface warms the air: sunlight heats the ocean and land, which then pass heat to the atmosphere. Snow and ice reflect more of that sunlight instead. Covering more of the surface can therefore reduce a source of atmospheric warming. That helps explain why the change in surface coverage would lead to cooler air, even though it wasn't a specific gap we identified before reading the choices.

• D

  This tells us that sunlight's passage through the atmosphere supplies most of its heat. But sunlight passes through the atmosphere whether it ultimately reaches snow, ocean water, or bare land. We still need a reason the difference in surface coverage affects atmospheric temperature. D doesn't explain that difference as C does.

• E

  This compares one kind of uncovered soil with another. The argument compares snow and ice with the ocean and land without snow cover, and we're already told snow and ice are more reflective. Learning that lighter soil reflects more than darker soil doesn't strengthen the further claim about what greater snow and ice coverage will do to the atmosphere.