STUDENT NAME: STUDENT NUMBER: Faculty of Science FINAL EXAMINATION ATMOSPHERIC & OCEANIC SCIENCES ATOC 185 EARTH & PLANETARY SCIENCES EPSC 185 NATURAL DISASTERS Examiners: Professor J. Gyakum and Professor J. Stix Wednesday, 16 December 2009, 9:00 AM-12:00 PM Instructions: 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 notes, texts, or calculators are permitted. Translation dictionaries are permitted. Please place your name and student number on each page of this exam. Good luck and happy holidays. This exam comprises 10 pages, including the cover page.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 2 of 10 1. Provide one reason to explain why tornadoes account for a larger number of fatalities, on average, than hurricanes. Take one: There is a relatively short warning time, on the order of minutes, or as much as an hour. The damage tends to be catastrophic. Tornadoes can have wind speeds greater than those of even the strongest of hurricanes. 2. Provide two reasons why people tend to ignore tornado warmings. Take two: Many victims live in mobile homes, and do not have access to safe evacuation shelters People tend to ignore warnings that fall outside of the normal tornado season. In fact, tornadoes may occur during any month of the year. Optimism bias: bad things only happen to other people Warnings may be ignored, because there may be no evacuation plan, or because people do not think there is a significant threat. 3. During the past 60 years, has the number of reported tornadoes in North America been increasing, decreasing, or remaining the same? Provide a plausible explanation for your answer. Increasing. Take one: People are now more knowledgeable about spotting or detecting more tornadoes. Population encroachment into areas not previously inhabited. The number of tornadoes has actually increased. 4. Where in the world are the most tornadoes reported? Provide at least two plausible reasons for your answer.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 3 of 10 North America Take two: Warm, moist air source Cold air source All significant mountain ranges are oriented north-south 5. Distinguish between a tornado watch and a tornado warning by defining each term. Tornado watch: Indicates that conditions are favorable for tornadoes to form. The watch may be given as much as 12 hours in advance of the potential event. Tornado warning: This means that a tornado is believed to be present in the warning area. 6. Why is a freezing rain storm potentially more dangerous than a heavy snowstorm? The loading of heavy ice on surfaces does not occur in heavy snowstorms. Removal of ice is more difficult than removal of snow. 7. Define supercooled water. How does this phenomenon relate to an ice storm? This is liquid water that exists at temperatures below 0 degrees C.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 4 of 10 An ice storm consists of liquid water existing at such temperatures, or supercooled water, which freezes upon impact with a surface. 8. Is the Montreal community more or less vulnerable to an ice storm of the same severity as that of the 1998 ice storm? Explain your reasoning. Quite possibly more vulnerable. Reasons may include reliance on more fragile infrastructures, such as online banking, and the internet in general, both of which are dependent on computer servers that may be especially vulnerable to power outages. Accept answers that are well reasoned, even for less vulnerable. 9. During a freezing rainstorm, approximately what temperatures would you expect to observe near the ground? How would you expect the temperatures to change as the elevation increases? The temperatures near the ground would be less than 0 deg C. These temperatures would rise to values above 0 deg C, so that any frozen precipitation would melt aloft. This is an inversion. 10. Would you expect to observe more freezing rain storms in Montreal, or in Vancouver, British Columbia? Explain your reasoning. Montreal. This location has more instances of inversions in which the surface temperatures are less than 0 deg C.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 5 of 10 11. Given that actual weather records exist only as far back as 150 years, discuss one technique that may be used to assess temperature changes for a much longer period. We use proxy data, such as: Take one: Tree rings Ice cores Fossil pollen Ocean sediments Corals 12. Given that a major volcanic eruption has occurred, what immediate impact would this eruption have on the daily range of temperature downwind of the eruption? Explain your reasoning. The range decreases, because the ash blocks sunlight, lowering the maximum temperatures, and the minimum temperatures are also warmed because of lack of radiational cooling. 13. As the Arctic sea ice coverage continues to decrease during the late summer, name one significant negative impact of this trend, and explain why such an impact would be negative. More coastal erosion, because of storm wind-driven waves. Other well-reasoned answers are acceptable.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 6 of 10 14. What is the primary reason that we have observed an increase in the number of significant (category 3 or greater) Atlantic basin hurricanes during the past 30 years? Explain your reasoning. The sea surface temperatures are rising, and are providing an environment for enhanced hurricane intensity, as a result of more latent heating. 15. Given that carbon dioxide emissions caused by the industrial revolution have occurred only during the past 200 years, discuss one plausible explanation for the fluctuations in climate prior to the industrial revolution. When global temperatures become warmer, carbon dioxide is released from the oceans. When changes in the Earth's orbit trigger a warm (or interglacial) period, increasing concentrations of carbon dioxide may amplify the warming by enhancing the greenhouse effect. When temperatures become cooler, CO2 enters the ocean and contributes to additional cooling. 16. Explain why stony meteorites are more common than metallic meteorites.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 7 of 10 Stony meteorites come from the mantle of asteroids which is large relative to the metallic core from whence metallic meteorites are derived. 17. Both large meteorite impacts and large-scale basaltic volcanism can produce short-term global cooling effects which may contribute to mass mortality and mass extinction events. Discuss the underlying causes of this type of cooling. For meteorites, the dust injected into the air from the impact event and soot from wildfires block the sun s light, causing cooling. If the impact vaporizes sulfur-rich rock (e.g., anhydrite), the vaporized sulfur will be in the form of sulfur dioxide (SO 2 ), which is an absorber of UV radiation. This causes significant and efficient cooling. Basaltic volcanoes emit significant SO 2,and some ash, causing short-term cooling. 18. Meteorites excavate craters which are much, much larger than the meteorite body itself. Why is this so? This is because they are traveling so fast and release so much energy upon impact. 19. How large must a meteorite be to have global consequences? About 1 km. 20. List three ways a tsunami can form. Anything which causes displacement of water:
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 8 of 10 -submarine earthquake -oceanic meteorite impact -submarine caldera collapse -pyroclastic flows entering water -landslide entering water -submarine landslide 21. You are sailing your boat across the Pacific Ocean. You have reached the middle of your voyage where the water depth is many thousands of meters. A tsunami generated off the coast of Japan reaches your location. What effects would you feel as the tsunami waves pass you? Nothing. 22. Discuss the relative tsunami risk for people living on the west coast of Vancouver Island, British Columbia, and the eastern coast of Long Island, New York. The west coast of Vancouver Island is vulnerable (a) to locally-generated tsunamis caused by subduction earthquakes of the Cascadia subduction zone, and (b) to distant tsunamis generated around the Pacific ring of fire by subduction earthquakes and submarine volcanic eruptions. The east coast of Long Island is less vulnerable due to a lack of subduction-related phenomena in the Atlantic Ocean basin. 23. The 2004 Sumatran earthquake and tsunami were dramatic examples of Nature s ability to cause large-scale devastation. What lessons can be learned from these events by people living in coastal areas of Cascadia (Pacific Northwest of Canada and the USA)? 1. Locally-generated megathrust earthquakes caused by subduction will generate significant ground motion which can be exacerbated in coastal areas due to liquefaction of water-saturated materials. 2. A locally-generated subduction earthquake, if it occurs offshore, may generate a very large and very destructive tsunami wave which will inundate the coastline minutes after the earthquake occurs. 24. List two main differences between a flow avalanche and a powder avalanche. -flow avalanches are dense and unexpanded, powder avalanches are dilute and expanded;
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 9 of 10 -powder avalanches move faster than do flow avalanches, other factors being equal; -flow avalanches are granular flows, powder avalanches are turbulent flows; 25. Discuss how a flow avalanche can transform into a powder avalanche. As a flow avalanche moves over steep topography such as a cliff, it breaks up and ingests air, allowing expansion of the flow to a powder avalanche. 26. If you are caught in a flow avalanche and buried up to your chin, you cannot extract yourself from the snow. Why is this so? The granular material, which has been slightly melted during flow from heat liberated by grain collisions, freezes and sets when the flow stops moving. 27. Discuss the trigger mechanisms of avalanches involving people. People trigger avalanches, e.g., back-country skiing and snowmobiling. 28. Avalanches sometimes flow into bodies of water such as lakes generating tsunami waves. In your opinion, which type of avalanche (flow avalanche or powder avalanche of similar size) would generate a larger tsunami? Justify your reasoning.
Final Exam, Natural Disasters ATOC/EPSC 185, 16 December 2009, Page 10 of 10 Probably a flow avalanche, due to its compact, unexpanded character and high density, which allow it to penetrate the surface of the water. The upper portions of an expanded powder avalanche will likely flow over the water surface due to a low density, rather than entering the water. 29. Discuss future vulnerability to natural hazards for people living in coastal areas. Are people in these areas becoming more vulnerable or less vulnerable? Explain your reasoning. People keep coming to coastal areas; as a result, infrastructure in these areas becomes increasingly fragile. Sea level is rising due to global warming, in some places significantly due to local subsidence. Higher sea surface temperatures promote more intense storms (e.g., hurricanes). Vulnerability is increasing. 30. Discuss three ways by which a megacity (> 10 million people) could reduce its vulnerability to naturally hazardous phenomena. -education -personal survival kits -proper zoning of hazardous areas -reduced consumption of resources (electricity, water, etc.) -less reliance on personal vehicles; -etc., etc. Other good responses very acceptable. *** Not for student use. For use in grading exam paper only. ***
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