Hurricane forecasters have difficulty determining maximum sustained surface-level winds. Reconnaissance aircraft usually obtain data from a flight level of 10,000 feet. However, in 1997, reconnaissance aircraft began deploying dropwindsondes in hurricanes. These weather instruments, carrying global positioning systems and affixed to parachutes, acquire detailed data from flight level down to surface level. Near the eyewall—the ring of towering thunderstorms surrounding a hurricane's eye—the strongest winds are usually found at around 1,600 feet, about 20 percent stronger than at flight level. In the hurricanes' outer reaches, however, wind maximums are typically found at higher elevations. The data also show that, near the eyewall, winds on top of a thirty-story building average about twenty miles per hour stronger than at ground level. Given the collective dropwindsonde data, forecasters typically estimate eyewall surface-level winds at about 90 percent of flight-level winds, with surface-level winds in the outer reaches at about 78 percent.
Hurricane Mitch in 1998, however, exhibited maximum flight-level winds no stronger than 150 miles per hour, yet dropwindsondes indicated much stronger surface-level winds. In this case, Mitch appeared to be weakening from the top down; the circulation at flight levels was decreasing but had yet to decrease at surface levels. This storm is a reminder that the typical estimates often need modification based on certain real-time factors, especially convective (warm-air updraft) intensity and sea-surface temperature.
1. The passage most strongly suggests that circulation in hurricanes
A. weakens at the eyewall before it begins to weaken in the outer reaches of a storm
B. near the outer reaches is typically strongest at elevations above the usual flight level of reconnaissance aircraft
C. is typically the same from flight level down to surface level before the hurricane begins to weaken
D. is usually faster at flight level than it is at surface level after a storm has begun to weaken
E. will not increase if sea-surface temperatures remain constant
2. The passage is primarily concerned with
A. describing various competing methods by which hurricane forecasters judge the accuracy of typical estimates of surface-level wind speeds
B. describing a method forecasters use to estimate surface-level wind speeds in hurricanes, while emphasizing that these estimates will sometimes require revision
C. explaining why it is that wind speeds vary according to altitude and position relative to the eyewall within a hurricane
D. explaining why advances in real-time data collection have precluded the need to estimate surface-level wind speeds in hurricanes
E. arguing that forecasters' estimates of surface-level wind speeds in hurricanes tend to be accurate despite the limitations of data collected from reconnaissance aircraft
3. Suppose that the windows on the top floor of a thirty-story building will shatter in 200 mile-per- hour winds. Under which of the following circumstances does the passage suggest that the windows would be most likely to break?
A. The building is in the outer reaches of a hurricane when surface-level winds reach 180 miles per hour.
B. The building is in the outer reaches of a hurricane when flight-level winds reach 200 miles per hour.
C. The building is in the eyewall of a hurricane when surface-level winds reach 150 miles per hour.
D. The building is in the eyewall of a hurricane when flight-level winds reach 200 miles per hour.
E. The building is in the eyewall of a hurricane when winds at 1,600 feet reach 200 miles per hour.
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21 Feb 2024, 03:32
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(03:42) wrong 
