Chapter 16 - Hurricanes Flashcards
What is a tropical easterly wave? How do these waves generally move in the Northern hemisphere? Are showers found on the eastern och western side of the wave?
A weak through (low pressure) from east to west. Precipitation on eastern side.
Why are skies often clear or partly cloudy in a hurricane’s eye?
the strong surface winds converge towards the center but never reach the eye due to Coriolis force.
What conditions at the surface and aloft are necessary for hurricane development?
Low pressure bottom and high pressure above.
Describe the vertical and horizontal development of a hurricane.
Horizontal structure: As one approaches the hurricane, the sky becomes overcast with cirrostratus
clouds; barometric pressure drops slowly at first, then more rapidly as we move closer to the center.
Winds blow from the north and northwest with ever-increasing speed as we near the eye. The high winds,
which generate huge waves over 10 m (33 ft) high, are accompanied by heavy rainshowers. As we move
into the eye, the winds slacken, rainfall ceases, and the sky brightens, as middle and high clouds appear
overhead. Vertical structure: Near the surface, moist tropical air flows in toward the hurricane’s center.
Adjacent to the eye, this air rises and condenses into huge cumulonimbus clouds that produce heavy
rainfall, as much as 25 cm (10 in.) per hour. Near the top of the clouds, the relatively dry air, having lost
much of its moisture, begins to flow outward away from the center. This diverging air aloft actually
produces an anticyclonic (clockwise in the Northern Hemisphere) flow of air several hundred kilometers
from the eye.
If a hurricane is moving westward at 10 knots, will the strongest winds be on its northern or southern side? Explain. If the same hurricane turns northward, will the strongest winds be on its eastern or western side?
Northern side; eastern side.
Why are North Atlantic hurricanes more apt to form in October than in May?
Hurricane season is from June-November.
Explain how a storm surge forms. How does it inflict damage in hurricane-prone areas?
The combined effect of high water (which is usually well above the high-tide level), high winds, and the net Ekman transport toward the coast, produces the storm surge—an abnormal rise of several meters in the ocean level—which inundates low-lying areas and turns beachfront homes into piles of splinters. The storm surge is particularly damaging when it coincides with normal high tides.
