Homework #5: Answers
1. Tropical cyclones are called ___ hurricanes ___ in the Atlantic Ocean, ____ typhoons ____
in the West Pacific Ocean and ____ cyclones ____ in the Indian Ocean.
2. Winds circulate in a ____ counterclockwise _____ direction around a tropical cyclone.
3. Tropical cyclones have __ low __ pressure at the surface and __ high __ pressure aloft.
4. The energy source for tropical cyclones is ___ the warm ocean water ___ that is released as vast amounts of ___ latent heat ____ generated by the heavy precipitation in the core of these storms.
5. The shape of tropical cyclones is more ____ round ____ and ____ symmetrical ____ than
extratropical cyclones because they form where there is little temperature contrast and,
therefore, they do not develop “fronts”.
6. Why are tropical cyclones “the most destructive storms on earth”?
Because of their large size, and in particular, their association with oceans
7. Strong vertical wind shear will _____ weaken _____ a tropical cyclone.
8. Why does vertical wind shear have this effect upon a tropical cyclone?
Tropical cyclones must remain vertically oriented in order to strengthen
9. The air ____ sinks ____ in the eye of a tropical cyclone, which results in clear skies.
1

10. The most intense updrafts and strongest winds are found in the ____ eyewall__ __ of a
tropical cyclone.
11. List the four environmental requirements for tropical cyclone formation.
1. Sea surface temperatures must be greater than 26.5°C (80° F)
2. The warm surface water must extend to depths of at least 60 meters
3. Weak vertical wind shear
4. Must be at least 5 degrees latitude from the equator
12. Because of the necessity for warm sea surface temperatures, tropical cyclones usually
only form in the ___ summer ____ and ____ fall ____ seasons.
13. Why does the warm surface water layer need to be at least 60 meters deep in order for a
tropical cyclone to form?
The winds of the tropical cyclone “stir” the water, which causes upwelling of water from below the surface. The warm water must be deep enough so that the deeper cool water does not make it to the surface
14. Why do tropical cyclones not form within 5 degrees of the equator?
Because there is no Coriolis force near the equator, it is not possible to generate a cyclonic circulation
15. Tropical cyclones originate as ____ clusters of thunderstorms ___ within or near the ITCZ.
16. Tropical cyclones in the Atlantic Ocean most frequently originate from
___ African Easterly Waves ___ which form over the African continent during the monsoon season.
17. Even though these African weather systems can become destructive tropical cyclones, they severe an extremely important function for the African people. What is that function?
These systems are the essential water source for agriculture in this region
2

18. Tropical cyclones tend to continue to deepen and strengthen because of a __ positive __
feedback process.
19. What is a tropical disturbance?
Any organized cluster of thunderstorms
20. When a tropical disturbance develops a low pressure center and cyclonic circulation it
is called a ______ tropical depression _______.
21. A tropical cyclone receives a name when it becomes a ____ tropical storm _____.
22. When sustained winds reach 74 mph a tropical cyclone in the Atlantic Ocean becomes a
_____ hurricane _____.
23. Tropical cyclones tend to track with the anticyclonic flow around the
____ semi-permanent subtropical high pressure systems ______.
24. True or false..........The majority of tropical cyclones make landfall.
False
25. If a tropical cyclone reaches middle latitudes it may undergo an extropical transition in which it begins to feed off the energy of _______ the jet stream _______, develop
____ fronts ____ and become a(n) _____ extratropical cyclone _______.
26. What two conditions will generally result in intensification of a tropical cyclone?
1. Warm sea surface temperatures
2. Weak vertical wind shear
3

27. What three mechanisms result in the weakening and eventual demise of a tropical
cyclone?
1. Vertical wind shear
2. Cool sea surface temperatures
3. Land
28. What two things about tropical cyclone landfall results in its eventual demise?
1. Loss of its energy source (warm ocean waters)
2. Friction
29. “Hurricane season” in the Atlantic Ocean runs from ____ June 1 _____ to
___ November 30 ____with a peak in ___ mid September ____.
30. a) Hurricanes are categorized by intensity based upon ______ wind speed _______.
b) The intensity scale is called the _____ Saffir-Simpson Scale _________.
31. What are the three tropical cyclone “modes of destruction”?
1. Wind
2. Storm surge
3. Rainwater flooding
32. a) Which of these three modes causes the most hurricane/typhoon/cyclone (of hurricane
strength) related fatalities?
Storm surge
b) Which of these three modes causes the most deaths related to all tropical cyclone (not
necessarily of hurricane strength) activity?
Rainwater flooding
33. The storm surge is greatest to the _____ right _____ of the path of the eye of a tropical
cyclone.
34. The storm surge is enhanced by ___ high tide ____ and ___ shallow inland bays ___.
4