Here is a question about this article: Under the Köppen climate classification, Philadelphia falls in the northern periphery of the humid subtropical climate zone (Köppen Cfa). Summers are typically hot and muggy, fall and spring are generally mild, and winter is cold. Snowfall is highly variable, with some winters bringing only light snow and others bringing several major snowstorms, with the normal seasonal snowfall standing at 22.4 in (57 cm); snow in November or April is rare, and a sustained snow cover is rare. Precipitation is generally spread throughout the year, with eight to twelve wet days per month, at an average annual rate of 41.5 inches (1,050 mm), but historically ranging from 29.31 in (744 mm) in 1922 to 64.33 in (1,634 mm) in 2011. The most rain recorded in one day occurred on July 28, 2013, when 8.02 in (204 mm) fell at Philadelphia International Airport.
What is the answer to this question: How much rain does Philly get on average?
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So... 41.5 inches


Here is a question about this article: A solar chimney (or thermal chimney, in this context) is a passive solar ventilation system composed of a vertical shaft connecting the interior and exterior of a building. As the chimney warms, the air inside is heated causing an updraft that pulls air through the building. Performance can be improved by using glazing and thermal mass materials in a way that mimics greenhouses.
What is the answer to this question: What is a solar chimney?
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So... a passive solar ventilation system


Here is a question about this article: Regardless of the ability of the Luftwaffe to win air superiority, Adolf Hitler was frustrated that it was not happening quickly enough. With no sign of the RAF weakening, and Luftwaffe air fleets (Luftflotten) taking punishing losses, the OKL was keen for a change in strategy. To reduce losses further, a change in strategy was also favoured to take place at night, to give the bombers greater protection under cover of darkness.[b] On 4 September 1940, in a long address at the Sportspalast, Hitler declared: "And should the Royal Air Force drop two thousand, or three thousand [kilograms ...] then we will now drop [...] 300,000, 400,000, yes one million kilograms in a single night. And should they declare they will greatly increase their attacks on our cities, then we will erase their cities."
What is the answer to this question: What kind of strategy did the Luftwaffe use to give their bombers better protection?
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So...
cover of darkness