Most of the ultraviolet radiation reaching the Earth's atmosphere from the Sun is absorbed by the layer of stratosphe...
Julie-VAugust 12, 2019
Clarifying the Discrepancy
Hi LSAT Max,
Is the discrepancy in this question stem the confusion as to why there wasn't an increase in UV radiation since the stratospheric layer slightly decreased? It took me multiple reads to absorb what the stimulus was trying to get at.
Many thanks in advance for the help!
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@Julie-V, yes, that's precisely what the discrepancy is in this stimulus. Did you have any other questions on this problem? Let us know if you'd like an explanation, and we'll be happy to walk through this question.
nizhoniNovember 6, 2019
I'd like an explanation :-D
shunheJanuary 8, 2020
Hi @nizhoni,
Thanks for the question! Let's break this question down a bit. The first premise tells us that most UV radiation doesn't reach the Earth's surface, since it's absorbed by stratospheric ozone. The second premise then tells us that there's less stratospheric ozone over North America. But, somehow, the average level of UV radiation detected by North American research stations decreased over this period of time as well. This is weird, since we'd expect more UV radiation if there were less stratospheric ozone to block it. A number of possibilities could explain it: maybe the research stations' measurements are wrong, or maybe something else is helping block their UV radiation. This is what (D) tells us. It gives us an alternate explanation as to why the UV radiation measurements have gone down - ozone pollution blocks it instead, and so even though there's less stratospheric ozone, the ozone pollution makes up for it. Hope this helps!
Gabby_teixeiraApril 14, 2020
Is E incorrect because we need to solve for the discrepancy that must account for North America in the explanation?
