2008 Midterm Answers.pdf

9 Pages

Atmospheric & Oceanic Sciences
Course Code
ATOC 185
John Stix

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Name:________________________________Student number:____________________ ATOC 250, EPSC 250 Natural Disasters Mid-Term Examination, 20 October 2008, 6:30-8:30 PM Instructions: There are 30 questions on this test. Answer your choice of any 25 questions. Each question is worth 4 points. If you answer more than 25 questions, only the first 25 questions will be marked. All answers should be short-answer, from several words to several sentences. Provide all answers on the test sheet itself. No aids are allowed except for translation dictionaries. This test comprises 9 pages. 1) Name at least 4 conditions necessary for the formation of tropical cyclones. Low values of wind shear Some form of pre-existing disturbance (front, easterly wave) 0 Warm water (greater than 27 C) Warm water to a depth of at least 60m Sufficiently far from the equator that the Coriolis force can create a circulation 2) Briefly list or discuss the stages (life cycle) of a tropical cyclone. 1) Tropical Depression-First signs of an organized circulation 2) Tropical Storm-System becomes named, some indication of a symmetric structure 3) Hurricane/Typhoon-Eye forms, presence of a banded structure Name:_____________________________Student number:___________________Page 2 3) What makes some areas more susceptible to storm surge damage than others? A region’s susceptibility to storm surge is largely determined by how steep the continental shelf is. Regions where there is a shallow slope to the continental shelf will tend to experience much higher storm surges than regions with a steep continental shelf. 4) Hurricane Katrina is sometimes referred to as a man made disaster. Briefly describe how human intervention may have contributed to loss of life in the New Orleans area. A large problem in the New Orleans area is that most of the city is below sea level. Consequently, levees are built in an attempt to hold back the water, and the levees are built to a height of about 17 ft above sea level to resist floods and storm surges. However, if the levees are breached, the flooding that occurs in the city becomes worse than the flooding that we would have otherwise had because the levees can actually “trap” the water in the city. 5) What are some of the factors which limit the frequency of hurricane development in the Atlantic Basin? Wind shear is too strong Descending air associated with Azores High Middle layer of the atmosphere are too dry. 6) The trade winds in the Pacific Ocean are stronger than normal. Are the conditions in northern Australia likely to be wetter or drier than normal? Explain your answer. Stronger than normal trade winds will result in warmer water temperatures over Australia; otherwise known as La Nina conditions. This enhancement of the warm water results in a stronger Walker circulation, which means that there will be greater rising motion and more rain than we would normally expect, particularly over northern Australia. 7) The economic impacts of tropical cyclones are relatively straightforward, but what are some of the ecological or environmental impacts that these storms can have? Name:_____________________________Student number:___________________Page 3 Two of the most important impacts on the ecology during a hurricane include significant coastal erosion/destruction from a combination wind and waves, as well as pollution of streams, lakes, and rivers from inland flood waters, particularly over agricultural areas. The fertilizer from crop lands can actually run into the rivers and lakes causing algae blooms, which can in turn kill fish and other organisms. 8) Why is Indonesia so susceptible to negative impacts from El Niño? What are these impacts? Indonesia is susceptible to negative impacts from El Nino due to the large bio-mass of the rainforest. During an El Nino, drought conditions in what is essentially a rainforest produces conditions that are very favorable for severe forest fires. This can result in serious health problems for the locals, and can also contribute to greenhouse warming. 9) Perhaps counter-intuitively, drought conditions in normally wet areas can lead to increases in disease. Briefly explain this apparent contradiction. In normally wet or lush areas, drought conditions can lead to an increase in stagnant water as rivers and streams dry out. This can lead to an increase in the mosquito population, and consequently, to an increase in cases of malaria. 10) What would you expect to happen to typhoon frequency and intensity in the West Pacific during a strong El Niño event? Briefly explain your answer. During a strong El Nino, sea surface temperatures over the West Pacific would tend to be cooler than normal. This would likely result in fewer, and less intense Typhoons in this region 11) List some of the factors that make present day populations both more and less vulnerable to natural disasters than 50 years ago. Name:_____________________________Student number:___________________Page 4 Factors that make us more vulnerable mainly center around the fact that there are many more people who are living in high risk areas such as Miami as compared to 50 Years ago. Along with that, the potential economic loss from damage to infrastructure is significantly higher. Factors that make us less vulnerable are mainly associated with better warning systems, as well as improved building/infrastructure codes which can mitigate loss. 12) Briefly discuss what some of the factors are that define how a population responds to warnings of impending natural disasters. Answers here can be highly varied. One of the many factors that has a large impact is the idea of collective memory. For example, if people can’t remember the last time a strong hurricane impacted them, they are less likely to respond quickly to evacuation orders. Also, the number of false alarms “the boy who cried wolf” syndrome can make people more complacent in the face of a warning. A person’s financial and physical well being is also at issue. 13) Explain the difference between “hazard” and “risk”. Hazard: potential threat to humans and their welfare. Risk: probability of loss (deaths, injuries, damage, disruption of economic activity) as a result of a particular natural event. 14) Explain the concept of “recurrence interval”. Recurrence interval: average time interval between the occurrence of two events of a given magnitude. 15) Compare and contrast lava flows and pyroclastic flows in terms of their potential hazard. Name:_____________________________Student number:___________________Page 5 Lava generally flows slowly, so there is time to get out of the way, evacuate, etc. Pyroclastic flows generally move very fast, so little time is a
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