[cxr]

I don't know why you're yes-anding the premise. For this sentence the authors of the study would have been rather more interested whether the subjects would look up the term "aits".

Aside from that, there's actually isn't a lot more to it, which makes it an unfortunate sentence to focus on, because it results in a caricature of the study. "There's just fog everywhere" and "the author is trying to portray a dark, grim, barely visible image of the city" are just barely short of the desired results. It just happens that this mostly straightforward (not complicated) sentence lies between/among many other far less straightforward ones. The problem is glossing where it is inappropriate to do so—and being overly comfortable doing so—which the authors of the study criticize as "oversimplification":

> 96 percent of the problematic readers used oversimplified phrases at least once to summarize a sentence in the test passage while 61 percent used this method for five or more sentences. Often, subjects used this tactic as a shortcut when they became overwhelmed by a sentence with multiple clauses. One subject disclosed that oversimplifying was her normal tactic[…] Those subjects, however, who relied on oversimplification became more and more lost as they continued to read