How many "u"s can you find in:
Forget about rain delays or missing flight crews. Climate change means the real problem for aviation will be heat waves.
Last month, Phoenix enduring a blistering heat wave, with temperatures so high that airport officials had to cancel dozens of flights. The reason was two-fold. First off, some jet engines risk catching on fire in extreme heat. And when air gets hot, it expands and becomes less dense—so an airplane’s wings can’t generate enough lift to get off the ground. Planes either need to speed up during take-off or use a longer runway.
But Phoenix’s flight delays aren’t a one-off event. As the Earth’s climate undergoes a 1 to 3 degree Celsius warming over the next half-century, extreme heat waves will hit more frequently. Some of these heat waves will hit airports with short runways. Forget about rain delays or missing flight crews. At places like Washington’s Reagan National Airport, New York’s LaGuardia Airport, and Dubai International, the real trouble will come during heat waves.
The scientists looked at five common commercial airplane models—the Boeing 737-800, Airbus A320, Boeing 787-8, Boeing 777-300, and Airbus A380—and calculated how their takeoffs would be affected at 19 airports around the world, based on projected temperatures from 27 different global climate models. The runways represented the most common climates, elevations, and runway conditions at busy airports around the world—including US airports in Denver, Phoenix, Chicago, Atlanta, New York, Washington, DC, Los Angeles, Houston and Miami.
The good news for air travelers is that London, Paris, and JFK in New York will be able to shrug off the worst of future heat waves. But a Boeing 777-300 departing from Dubai at the time of the daily highest temperature may be weight-restricted about 55 percent of the time according to the study, which appears today in the journal Climactic Science. Because of the short runways, airplanes at Washington’s Reagan-National (7,170 feet) and New York’s LaGuardia (7,000 feet) will also have to lighten their load to get off the ground. Expanding the runways probably won’t work, given that they are either sandwiched along the Potomac River or Jamaica Bay.
Heat waves aren’t the only problem facing the aviation industry as the Earth’s climate changes rapidly. Other scientists have calculated that severe turbulence—the kind that sends drink carts flying and sometimes even unbuckled passengers—will increase over certain transatlantic routes that follow the meandering jet streams.
There are plenty of solutions out there, some more complicated than others. Flights may have to leave earlier in the day when its cooler, Horton suggests, or aircraft manufacturers may have to make planes lighter. Or engineers could step in, building some kind of special new wings that generate additional lift. There’s one other option that probably won’t happen: leaving three or four paying customers back at the terminal in order to make the takeoff weight.
Last year was the hottest year since scientists started keeping records in the 19th century. It's no fluke---because it's humanity's fault.

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In that passage, there are sixty-eight occurrences of the letter "u."
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