Question | Answer |
tropical cyclone | massive storms that spiral around low air pressure and have strong winds;5-25 degrees N/S of equator |
typhoon | forms over Western Pacific |
cyclone | forms over Indian Ocean and S. Pacific |
hurricane | forms over Atlantic and E. Pacific; >74 mph = class 1 hurricane |
spiral | counterclockwise = N Hem; clockwise = S Hem; because of Coriolis Effect; average diameter 480 km |
Coriolis Effect | winds spiral because of Earth's rotation |
eye | center, few clouds, light winds; has lowest surface pressure; air sinks, becomes warmer and drier; measure air pressure here for storm strength; not all hurricanes have one; 8 to 200 km diameter |
eyewall | wall of clouds around eye; deadliest part of storm; moist air rising then vapor condenses; release energy = heavy t-storms with heavy rain and winds |
rainbands | regions beyond eyewall of heavy t-storms that spiral outward from center; moist air rising the condenses; strongest 90 degrees of storm track; light rain between, air not rising |
needed for a hurricane the form | warm ocean water - >27 degrees C; deep enough 200 m.; rising air spirals; low-pressure area; light winds and light wind-shear to help cause convections but not to much to destroy formation; if it forms off of Africa at the equator = "kick start" |
process of formation | water evaporates which carries water to atmosphere, vapor condenses to a cloud which releases stored energy, t-storms begin = tropical depression |
causes for weakening | high wind shear, cooler ocean water, moist and rising air is stopped (SAL), moving over land |
wind shear | change in speed and/or direction of wind with change in altitude; high = weaken; low = strengthen |
cooler ocean | less energy = less evaporation = less energy to atmosphere; winds take system North to cooler water (US Atlantic coast); moves to an area where cold ocean current flows (California); moves over cool water stirred up by a previous storm |
Saharan Air Layer (SAL) | sometimes blows out from N Africa during summer; weakens/prevents: interrupts updrafts = moist air cannot rise, mix w/hurricane and takes moisture out of the storm, can have strong wind = high wind shear |
temperature inversion | warmer less dense air lies above a layer of cooler more dense air |
landfall | puts storm over no warm water = no energy/water source, still has high winds and heavy rain - can be severe even inland |
what satellite images do not show | they show size, location past tracks of a hurricane, but they do not show the flow of air |
hurricanes track wast in the Atlantic but often go around a Bermuda_____while staying off the Atlantic coast due to US______syatems | Bermuda high; US weather systems |
where in a hurricane are the convections highest | the eyewall |
____air sinking in the eye does not have enough energy to keep water as a vapor. As the air sinks,though, an unusual thing happens; the air is warmed by the warm ocean and can carry open moisture. It then quickly risies in the_______ | cold air; in the eyewall |
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