# Chapter 10 Study Guide, Version 2: Hurricanes and Extratropical Cyclones This version follows the textbook section by section. Review each section's summary, key ideas, examples, and questions before moving to the next section. ## Chapter Learning Objectives - **LO:1:** Describe the weather conditions that create, maintain, and dissipate cyclones. - **LO:2:** Explain why it can be difficult to forecast cyclone behavior. - **LO:3:** Locate several geographic regions at risk for hurricanes and extratropical cyclones. - **LO:4:** Give examples of the effects of cyclones in coastal and inland areas. - **LO:5:** Recognize linkages between cyclones and other natural hazards. - **LO:6:** List the benefits derived from cyclones. - **LO:7:** Describe adjustments that can minimize damage and personal injury from coastal cyclones. - **LO:8:** Propose prudent actions to take for hurricane or extratropical cyclone watches and warnings. ## 10.1 Introduction to Cyclones (LO:1) ### Section summary A **cyclone** is a low-pressure system with rotating winds. Cyclones are classified as tropical or extratropical according to where they form and the temperature structure of their core. Both types can cause damaging winds, heavy precipitation, flooding, and coastal storm surge, but they form and behave differently. ### Tropical and extratropical cyclones | Feature | Tropical cyclone | Extratropical cyclone | |----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------| | Typical setting | Warm tropical or subtropical ocean, commonly between 5 and 20 degrees latitude | Temperate latitudes, commonly between 30 and 70 degrees, over land or water | | Core | Warm | Cool | | Fronts | Not associated with fronts | Commonly associated with fronts and strong temperature contrasts | | Main energy source | Heat and moisture from warm ocean water; latent heat released during condensation | Horizontal temperature contrasts between air masses, supported by upper-level winds | | Regional names and hazards | Called hurricanes in the Atlantic and eastern Pacific, typhoons in the northwest Pacific, and cyclones in parts of the Indian and South Pacific oceans | May be called nor'easters when tracking north along the eastern North American coast; can bring windstorms, rain, snow, and blizzards | The Coriolis effect deflects winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, producing counterclockwise rotation around Northern Hemisphere lows and clockwise rotation around Southern Hemisphere lows. Cyclones rarely develop within about 5 degrees of the equator, where the Coriolis effect is weak. ### Tropical cyclone intensity and names - A tropical disturbance may develop into a **tropical depression**, then a **tropical storm**, and, if sustained winds reach at least 119 km/hr (74 mph), a **hurricane**. - A tropical storm is assigned a name when its maximum sustained winds exceed about 63 km/hr (39 mph), according to the textbook. - In the Atlantic and eastern Pacific, these storms are called hurricanes; in the northwest Pacific, typhoons; and in some other regions, cyclones. - Atlantic hurricane names come from internationally coordinated lists. Naming helps forecasters and the public distinguish storms; especially deadly or damaging names may be retired. - Extratropical cyclones may be named for their source region or wind direction, as with Alberta Clippers and nor'easters. The **Saffir-Simpson Hurricane Wind Scale** classifies hurricanes by sustained wind speed. Category 3-5 storms are described as major hurricanes in the textbook. The scale estimates wind-related damage potential; storm surge and rainfall also depend on storm size, track, speed, coastline, topography, and tide. | Category | Sustained wind speed in the textbook | General damage potential | |----------|-------------------------------------:|------------------------------------------------------------------------------------------------------------------------------| | **1** | 119-153 km/hr (74-95 mph) | Damage to unanchored mobile homes, vegetation, signs, and some coastal roads and piers. | | **2** | 154-177 km/hr (96-110 mph) | Roof, door, and window damage; trees, mobile homes, and piers may be damaged; low routes may flood. | | **3** | 178-209 km/hr (111-129 mph) | Structural damage to some small buildings; mobile homes may be destroyed; coastal flooding and evacuation may extend inland. | | **4** | 210-249 km/hr (130-156 mph) | Extensive structural damage; mobile homes destroyed; major damage near shore and large-scale evacuation may be needed. | | **5** | More than 249 km/hr (157 mph) | Catastrophic wind damage and major destruction of buildings and vegetation; extensive evacuation may be required. | The textbook's scale table also lists typical storm-surge ranges by category. These should not be treated as a complete storm-surge forecast because surge depends on more than wind category. ### Key terms - **Cyclone:** Low-pressure system with winds rotating around its center. - **Tropical cyclone:** Warm-core cyclone that develops over warm tropical or subtropical ocean water. - **Extratropical cyclone:** Cool-core, frontal cyclone of the midlatitudes. - **Tropical disturbance / depression / storm:** Successive stages of organized tropical weather and increasing wind intensity. - **Hurricane / typhoon:** Regional names for intense tropical cyclones. - **Saffir-Simpson Hurricane Wind Scale:** Classification of hurricanes by sustained wind speed. - **Major hurricane:** Category 3, 4, or 5 hurricane in the chapter's classification. ### Section 10.1 review questions 1. What is a cyclone, and how do tropical and extratropical cyclones differ? 2. Why do cyclones rarely form directly at the equator? 3. How does a tropical disturbance progress to a hurricane? 4. What does the Saffir-Simpson scale measure, and what other factors affect actual damage? 5. How are tropical cyclones named in different ocean basins? ## 10.2 Cyclone Development and Movement (LO:1 and LO:2) ### Section summary Tropical cyclones draw energy from warm ocean water and latent heat released as moist air rises and condenses. Extratropical cyclones develop along fronts where temperature contrasts interact with the jet stream. Both storm types are steered by large-scale atmospheric circulation, making their paths and intensity challenging to predict. ### Tropical cyclone development Many Atlantic tropical disturbances begin as **easterly waves**: elongated low-pressure troughs that move west from Africa with the trade winds. Converging air east of a trough rises, forming clouds and thunderstorms. Most disturbances do not become hurricanes. For a hurricane to form and intensify, the chapter identifies four key environmental requirements: 1. Warm ocean water of at least about 26 degrees C (79-80 degrees F) extending to a depth of roughly 46 m (150 ft.) or more, to supply heat and moisture. 2. An atmosphere that cools sufficiently with height to allow moist air to remain unstable and rise; a warm layer aloft can cap development. 3. Little vertical wind shear, so upper-level winds do not disrupt the storm's vertical structure. 4. Enough distance from the equator for the Coriolis effect to produce rotation. As warm, moist surface air converges and rises, water vapor condenses and releases latent heat, fueling further uplift. A mature hurricane has spiraling rain bands, a central **eye** with descending air and relatively calmer conditions, and an **eyewall** surrounding the eye where winds and rainfall are strongest. Tall thunderstorm clouds called **hot towers** release large quantities of heat and may signal intensification. Hurricanes generally weaken over land or cooler water because their warm-water energy source is removed. They can also transition into extratropical cyclones when they encounter an upper-level trough, fronts, or cooler water at higher latitudes. ### Hurricane movement and the North Atlantic Oscillation Hurricane movement is controlled by the Coriolis effect and by steering winds in the middle and upper troposphere, roughly 8-11 km above the surface. In the North Atlantic, storms often move west with the trade winds, then curve north around the western side of the Bermuda-Azores High and may turn northeast into the westerlies. The high's position and strength affect where storms turn. Weak steering currents can lead to unusual paths, including loops or reversals. The **North Atlantic Oscillation (NAO)** describes pressure differences between the Bermuda-Azores High and the subpolar low near Iceland. Positive and negative phases affect the strength and path of westerly winds and the jet stream. In the chapter's description, negative NAO conditions can produce a more meandering jet stream and increase cold-air outbreaks and snowstorms in the northeastern United States. ### Extratropical cyclone development Extratropical cyclones form where a strong horizontal temperature gradient, usually along a front, interacts with upper-level jet-stream patterns. Ridges and troughs bend or split the jet stream; upper-level divergence can help initiate a surface low. A typical cyclone evolves as follows: 1. Air masses move in opposite directions along a stationary front. 2. A wave develops along the front where upper-level winds diverge. 3. A surface low forms; cold air advances south on one side while warm air advances north on the other, creating cold and warm fronts. 4. The faster cold front catches up to the warm front and lifts the warm air. 5. An **occluded front** forms as warm air is trapped aloft. The mature cyclone's clouds commonly form a comma shape, with a comma head, comma tail, and sometimes a dry slot. 6. As the surface temperature contrast disappears, the pressure gradient weakens and the cyclone dissipates, often within a day or two. The system is fed by three broad airflows or “conveyor belts”: cold air circulating around the storm, warm moist air rising over cold surface air, and dry air aloft sinking behind the cold front. **Atmospheric rivers**, including the West Coast's “Pineapple Express,” can feed moisture into extratropical cyclones and produce intense precipitation. ### Factors that complicate forecasts - Tropical cyclones often develop far from land, where observations are sparse. - Forecasters must predict whether a storm will reach land, where and when it will strike, its intensity and size, and its rainfall and storm surge. - Small changes in steering currents, pressure systems, fronts, or ocean conditions can change a storm's track or strength. - Tropical cyclones may intensify or weaken quickly; extratropical cyclones can also develop rapidly, sometimes within 12-24 hours. - Computer models can disagree, especially on unusual interactions such as a tropical cyclone merging with a front. - Storm-surge forecasts also depend on coastline elevation and shape, water depth, wind, tide timing, and storm speed. ### Section 10.2 case studies - **North Atlantic Oscillation:** Positive and negative pressure patterns alter westerly winds, jet-stream position, storm tracks, and winter weather in Europe and eastern North America. - **Hurricane Katrina:** New Orleans' risk was well recognized before 2005. The city was largely below sea level, depended on levees, flood walls, and pumps, and had lost protective coastal wetlands. Katrina was Category 3 at its first landfall near the Mississippi Delta after reaching Category 5 over the Gulf. Flood-protection failures inundated about 85 percent of New Orleans. Forecasts and evacuation warnings were strong, but infrastructure, evacuation challenges, policy, and social vulnerability contributed to catastrophe. - **Abdulrahman Zeitoun, Katrina survivor story:** Zeitoun's family evacuated while he stayed in New Orleans. He initially mistook a temporary lull for the end of the danger; levee failures then flooded the city. His experience underscores why apparent calm after a hurricane does not establish that the hazard has passed and why people should follow official evacuation guidance. ### Section 10.2 review questions 1. What are easterly waves, and how can they develop into tropical disturbances? 2. What four conditions favor hurricane formation and intensification? 3. How do the eye, eyewall, rain bands, and hot towers differ? 4. What controls Atlantic hurricane tracks? 5. What is the NAO, and how can it affect storm tracks and weather? 6. Describe the main stages of extratropical cyclone development and dissipation. 7. Why are cyclone track, intensity, timing, and storm-surge forecasts challenging? 8. What did Katrina and Zeitoun's experience show about forecasting, infrastructure, and evacuation? ## 10.3 Geographic Regions at Risk for Cyclones (LO:3) ### Section summary Tropical cyclones are most common over warm tropical and subtropical oceans, while extratropical cyclones track through the midlatitudes. Coastal exposure, ocean temperature, storm tracks, prevailing winds, and local geography determine which regions face the greatest risk. ### Tropical cyclone risk - In North America, the highest hurricane risk is along the Gulf Coast from southern Texas to southern Florida and the Atlantic Coast from Florida north through Atlantic Canada. - Hurricane-strike probabilities are particularly high along southern Florida, Alabama, Mississippi, Louisiana, eastern Texas, and Cape Hatteras. - The eastern and Gulf Coasts average about five hurricanes per year across the region, according to the textbook. - Puerto Rico, the U.S. Virgin Islands, and U.S. territories in the Pacific are at risk. Hawaii and Atlantic Canada face a lesser but real threat. - Pacific tropical cyclones frequently affect Baja California and Mexico. Remnants can carry heavy rain into the southwestern United States as far east as Texas. - The northwest Pacific generally has about three times as many tropical cyclones as the North Atlantic. The Pacific and Indian Oceans overall have more storms than the Atlantic. - The South Atlantic and southeast Pacific rarely experience hurricanes because of cooler surface water; tropical cyclones generally do not form near the equator because the Coriolis effect is weak. - The Atlantic hurricane season officially runs June 1-November 30; most Atlantic hurricanes occur in August, September, and October. Southern Hemisphere cyclone seasons are generally January-April. North Atlantic hurricanes that form off western Africa commonly follow three broad tracks: west toward the Caribbean and out to sea; west through the Caribbean and into the Gulf; or west to the Caribbean and then north along the East Coast, sometimes reaching New England or Atlantic Canada. ### Extratropical cyclone risk Extratropical cyclones are a major hazard along the Pacific Coast, where winter storms bring high winds, heavy rain, flooding, erosion, and landslides. In the eastern United States and Atlantic Canada, coastal extratropical cyclones called **nor'easters** bring strong northeasterly winds, storm surge, rain, or snow. Extratropical cyclones also cause blizzards and windstorms across the central United States and Canada and dangerous storms on the Great Lakes. ### Section 10.3 review questions 1. Where are tropical cyclones most common globally, and why? 2. Which North American coastlines have the highest hurricane risk? 3. How do typical Atlantic hurricane tracks differ? 4. Where do extratropical cyclones create major hazards in North America? 5. Why are some ocean basins, including the South Atlantic, rarely affected by hurricanes? ## 10.4 Effects of Cyclones (LO:4) ### Section summary Tropical and extratropical cyclones cause deaths and property damage through storm surge, high winds, heavy rain, flooding, and linked hazards. In hurricanes, storm surge is often the deadliest effect; the textbook attributes about 90 percent of hurricane-related fatalities to it. ### Storm surge and coastal erosion **Storm surge** is a local rise in sea level caused mainly by winds pushing water toward shore. Major hurricanes and intense extratropical cyclones can produce surges exceeding 3 m (10 ft.); still higher surges have occurred internationally. Surge height is influenced by: - wind speed and the area or **fetch** over which the wind blows; - storm size, track, forward speed, and central pressure; - shallow nearshore water, bays, lagoons, and coastline shape; - whether surge arrives at high tide; and - the storm's position relative to the coast. In Northern Hemisphere hurricanes, the right-forward quadrant commonly has the strongest winds and greatest surge. Wind stress on the water is the main surge mechanism. Low atmospheric pressure contributes additional rise. Narrow bays or enclosed waters can amplify surge through resonance. A surge is a sustained rise in water level, not a single advancing wall of water; large waves riding on the surge cause much of the damage. Surge and waves erode beaches, dunes, roads, and sea cliffs. Water can cut **washover channels** through barrier islands and peninsulas, carrying sand inland into **overwash** fans. These channels can breach islands, isolate communities, or reshape coastlines. ### High winds Hurricane winds are strongest in the eyewall. Wind damage can be widespread, affecting buildings, trees, power systems, and transportation. Wind speeds typically decline after landfall, but some storms maintain strength or transition to extratropical cyclones. Hurricane Hazel, for example, retained damaging winds far inland and northward into Canada. Extratropical cyclones can also produce extreme winds. Examples in the chapter include the Big Blow of 1962 on the Pacific Northwest coast, the Great Lakes storm that sank the Edmund Fitzgerald in 1975, and the 1934 Mount Washington wind gust record. Blizzards and tornadoes can also be associated with extratropical cyclone systems. ### Heavy rain and inland flooding Tropical storms and even depressions can produce destructive rainfall and flooding without reaching hurricane strength. Inland flooding is especially severe when a storm: - moves slowly or stalls; - crosses hilly or mountainous terrain that enhances rainfall; - interacts with other weather systems; or - arrives when soils, streams, and lakes are already saturated. Tropical Storm Allison in 2001 never became a hurricane but produced extreme rainfall around Houston and Louisiana, causing widespread flooding, deaths, and billions of dollars in damage. Extratropical cyclones and atmospheric rivers can also bring prolonged rain, flooding, and heavy snow. ### Section 10.4 case examples - **Galveston hurricane, 1900:** Storm-surge flooding killed more than 6,000 people, making it the deadliest natural disaster in U.S. history, according to the chapter. - **Labor Day Hurricane, 1935:** Extreme winds in the Florida Keys blew a train off its tracks and killed hundreds. - **Hatteras Island, 2003:** A storm surge from Category 2 Hurricane Isabel cut several washover channels through the island. - **Tropical Storm Allison, 2001:** Intense rainfall caused severe inland flooding in Houston and southern Louisiana despite the storm never becoming a hurricane. - **Great Lakes storms:** Extratropical cyclone winds and waves have sunk ships, including the Edmund Fitzgerald in 1975. ### Section 10.4 review questions 1. What are the three major direct cyclone hazards in addition to associated flooding and severe weather? 2. How does storm surge form, and what factors can increase its height? 3. Why is the right-forward quadrant of a Northern Hemisphere hurricane especially hazardous? 4. What are overwash and washover channels, and how do they change barrier islands? 5. Why can a tropical storm or remnant cause severe inland flooding? 6. Compare the main effects of hurricanes and extratropical cyclones. ## 10.5 Linkages between Cyclones and Other Natural Hazards (LO:5) ### Section summary Cyclones are linked to coastal erosion, flooding, mass wasting, tornadoes, thunderstorms, snowstorms, and blizzards. Sea-level rise, coastal subsidence, and human development can amplify these linked hazards. ### Important hazard linkages - Storm surge and waves erode beaches, dunes, barrier islands, and sea cliffs. Coastal sand may be redistributed or permanently removed by waves and currents. - Cyclones can cause both saltwater coastal flooding from storm surge and freshwater inland flooding from rain. - Subsiding coasts are more vulnerable to storm-surge and rainfall flooding because land is lower relative to the sea and rivers. - Slow-moving storms can stall over saturated land, causing flash floods and river floods. - Heavy cyclone rain in mountainous terrain can trigger landslides and debris flows. Hurricane Mitch in Central America, for example, triggered widespread floods, landslides, and debris flows that killed at least 11,000 people. - Tropical cyclones can spawn tornadoes and severe thunderstorms. Sandy produced a tornado in Bermuda and heavy snow and power outages after interacting with an arctic front. - Extratropical cyclones produce blizzards and snowstorms as well as wind, rain, and coastal surge. - Sea-level rise increases the reach and consequences of storm surge; warmer ocean temperatures may contribute to greater hurricane intensity, although the chapter describes this as a concern/projection. ### Section 10.5 review questions 1. How are cyclones linked to coastal erosion, flooding, and landslides? 2. Why can a cyclone cause both coastal saltwater flooding and inland freshwater flooding? 3. How do subsidence and sea-level rise increase cyclone-related flood risk? 4. What other weather hazards can occur with or develop from cyclones? 5. How can a slow-moving cyclone create a cascade of hazards? ## 10.6 Natural Service Functions of Cyclones (LO:6) ### Section summary Cyclones are hazardous but also provide water and perform important functions in climate and ecosystems. Benefits often occur over large regions and long time periods, so they may be less visible than storm damage. ### Natural services - Cyclones and their fronts provide much of the precipitation in the United States and Canada. Tropical cyclones can bring needed rain to moisture-starved regions; extratropical cyclones supply winter rain and snow to the West Coast and snowpack that later recharges streams. - Tropical cyclones transport heat from the tropics toward the poles by lifting warm air and redistributing energy. - Storm winds transport plants, animals, and microorganisms over long distances, helping colonize new volcanic islands. - Cyclone waves can stir nutrient-rich water to the surface and support plankton blooms in oceans and estuaries. - Strong winds and waves disturb forests and reefs, remove weak or diseased trees, and contribute to ecosystem renewal and species diversity. - Cyclones are also visually powerful natural phenomena with aesthetic value. Natural services do not make cyclones harmless. The same storm that supplies water or renews habitat can cause catastrophic loss of life and property. ### Section 10.6 review questions 1. What is the primary natural service function of cyclones in the western United States? 2. How do cyclones redistribute heat and water? 3. How can storms contribute to ecosystem renewal and biological diversity? ## 10.7 Human Interaction with Cyclones (LO:7) ### Section summary Coastal population growth, development, wealth, and construction practices have increased exposure and the cost of cyclone damage. Climate change and sea-level rise may further increase coastal risk. Human decisions can either amplify hazards or reduce vulnerability. ### Human contributions to risk - More people and higher-value property are located in hurricane- and extratropical-cyclone-prone coastal counties. The textbook reports that about 53 percent of the U.S. population lives in coastal counties. - Building on barrier islands and shorelines increases exposure to surge, waves, erosion, and wind. - Removing dunes for development reduces natural protection from storm surge. - Seawalls and bulkheads can reflect storm waves and contribute to beach erosion, shifting risk along the coast. - Poorly attached roofing and other materials can become windborne projectiles, damaging buildings and injuring people. - Greenhouse-gas emissions warm the ocean and raise sea level. The chapter notes concerns that warmer ocean water could increase hurricane intensity and that higher sea level increases storm-surge reach. ### Section 10.7 review questions 1. How have coastal population growth and increasing property values changed cyclone risk? 2. How can dune removal, seawalls, and building practices worsen cyclone impacts? 3. How may climate change and sea-level rise affect hurricane and storm-surge risk? ## 10.8 Minimizing the Effects of Cyclones (LO:7 and LO:8) ### Section summary Cyclones cannot be prevented, but accurate forecasts, warnings, evacuation, resilient construction, flood mapping, and surge prediction can reduce losses. Forecasts remain uncertain, particularly for intensity and surge, so public response and preparation matter. ### Forecasting tools Hurricane forecast centers combine information from: - weather satellites, which detect and track storms over open ocean; - hurricane-hunter and research aircraft, which collect direct measurements of wind, pressure, and storm structure; - Doppler radar, which estimates rainfall and wind velocity and shows rain bands and the eye near land; - automated weather buoys and reports from ships; and - computer models, which combine observations to predict storm tracks and behavior. Computer models have substantially improved track forecasts, but intensity forecasts are more difficult. Model forecasts are less reliable farther into the future, and models can disagree on unusual tracks or storm interactions. Storm-surge forecasts use storm track, wind speed, size, forward speed, central pressure, tides, water depth, and coastal elevation. **LIDAR** provides detailed coastal elevation data. Surge models such as **SLOSH** and **ADCIRC** simulate surge height and inundation extent; ADCIRC can also include waves, tides, and river discharge. ### Watches and warnings - A **hurricane watch** in the chapter is issued when hurricane conditions are likely within about 48 hours; people should monitor official information and prepare. - A **hurricane warning** in the chapter is issued when landfall is likely within about 36 hours or less; people should complete preparations and follow evacuation orders. - Forecast centers, including the U.S. National Hurricane Center and Canadian Hurricane Centre, issue watches and warnings for their regions. ### Professional profile: Hurricane Hunters Air Force and NOAA reconnaissance crews fly specially equipped aircraft into hurricanes to measure storm conditions. These observations help forecasters estimate intensity and improve predictions. Crews may release dropsondes, instrument packages that measure conditions as they fall through the storm. ### Case study: Hurricane prediction and the future The textbook notes that improved forecasting, evacuation, and public awareness helped reduce U.S. hurricane deaths before Katrina, while coastal population and property growth drove damage costs upward. Its historical cost table, adjusted to 2017 dollars, reports $92.2 billion in U.S. Atlantic and Gulf hurricane damage in the 1990s and $279.5 billion from 2000-2010. The chapter also describes the 2017 Atlantic season as exceptionally costly and active, with 17 named storms and devastating impacts from Harvey, Irma, and Maria. These examples illustrate that better forecasts do not remove risk when exposure continues to grow and major storms overwhelm infrastructure. ### Section 10.8 review questions 1. What tools are used to detect and forecast hurricanes and extratropical cyclones? 2. Why can computer models predict a storm's track more accurately than its intensity? 3. What information is needed to predict storm-surge height and extent? 4. How do hurricane watches and warnings differ, and what should people do after each is issued? 5. What do Hurricane Hunters measure, and how do their observations help forecasts? 6. Why can hurricane-related economic losses continue to rise even as forecasts and evacuation improve? ## 10.9 Perception of and Adjustment to Cyclones (LO:7 and LO:8) ### Section summary People may underestimate cyclone risk even in regions with extensive storm experience. New residents may not understand the threat of a major storm, and repeated warnings for storms that miss an area can create complacency. Community and personal adjustments reduce risk only when people understand and act on warnings. ### Community adjustments - Maintain clear warning systems using broadcast media and, where necessary, sirens. - Develop evacuation plans before hurricane season; provide public transportation, open shelters, and manage outbound traffic routes. - Recognize that evacuating large coastal populations, barrier islands, people with limited mobility, and visitors can take days. - Enforce building codes for wind resistance and elevate structures to allow storm surge to pass beneath living areas. - Use land-use zoning, flood maps, insurance, buyouts, dunes, wetlands, and other natural buffers to reduce exposure. ### Personal adjustments Before hurricane season: - Learn local cyclone, flood, and evacuation risks and identify evacuation routes and shelters. - Prepare a household plan and discuss how family members, pets, and people needing assistance will evacuate. - Trim dead or dying branches, protect windows with shutters, and obtain appropriate flood insurance. - Keep flashlights, spare batteries, a radio, first-aid supplies, emergency food and water, a can opener, cash, medicines, and sturdy shoes. When a watch or warning is issued: - Monitor official local radio, television, and emergency alerts. - Gather supplies and follow the assigned evacuation route if ordered; leave early enough to account for traffic and limited routes. - Do not return until officials say it is safe. A lull in wind or rain does not mean that storm surge, flooding, or levee failure is over. ### Applying the fundamental concepts: Hurricane Sandy Sandy illustrates all five fundamental concepts: 1. **Science helps predict hazards:** Satellites, aircraft, observations, and computer models tracked Sandy. The European ECMWF model predicted its unusual turn toward New Jersey, while the U.S. GFS model initially suggested it would turn out to sea. 2. **Risk information can support decisions:** New York City ordered evacuation of Zone A, and coastal residents faced risks from surge, tides, and densely developed shorelines. 3. **Hazards are linked:** Sandy brought Caribbean flooding and mudslides, a Bermuda tornado, coastal erosion, U.S. storm surge, power outages, and heavy snow after merging with an arctic front. 4. **Humans can turn disasters into catastrophes:** High population density and extensive development exposed New York and New Jersey infrastructure and housing; low-lying areas and tunnels were vulnerable to flooding. 5. **Consequences can be minimized:** Evacuation, flood-zone building codes, warnings, and preparations reduced some impacts. The storm flooded areas beyond the earlier mapped zone, prompting updated maps and proposals for buyouts, natural buffers, and surge barriers. The chapter reports that Sandy reached about 1,800 km in diameter, made landfall in New Jersey as a post-tropical cyclone, and produced a record 4.3 m surge in New York Harbor. About 380,000 homes were damaged or destroyed and more than 8.5 million residences lost power across 16 states. The event shows that a cyclone can remain dangerous after it is no longer classified as a hurricane. ### Section 10.9 review questions 1. Why might residents underestimate cyclone risk or fail to evacuate? 2. What community planning and construction adjustments reduce cyclone losses? 3. What should households do before hurricane season and after a watch or warning? 4. Why can evacuation be especially difficult for densely populated coastlines and barrier islands? 5. How did Sandy challenge forecasts, maps, infrastructure, and public risk perception? ## Connections among the Sections - **10.1 to 10.2:** Cyclone classification reflects the different energy sources and processes that create tropical and extratropical storms. - **10.2 to 10.3:** Storm formation, steering winds, ocean temperatures, and fronts determine where cyclones travel. - **10.3 to 10.4:** Regional exposure shapes whether storm surge, wind, rain, snow, or inland flooding creates the greatest losses. - **10.4 to 10.5:** Cyclone effects trigger coastal erosion, flooding, landslides, tornadoes, blizzards, and other hazards. - **10.5 to 10.6:** Cyclones can cause destructive cascades while also transporting water and heat and renewing ecosystems. - **10.6 to 10.7:** Human settlement and land-use decisions change exposure to both cyclone hazards and benefits. - **10.7 to 10.8:** Forecasting, warnings, evacuation, engineering, and land-use planning reduce the risks associated with coastal development. - **10.8 to 10.9:** Forecasts save lives only when people understand warnings, prepare, and take appropriate action. ## Chapter-Wide Comparison Questions - How do tropical and extratropical cyclones differ in core temperature, location, energy source, and associated fronts? - How do tropical disturbances, depressions, tropical storms, and hurricanes differ? - What does the Saffir-Simpson scale measure, and what does it not capture? - What environmental conditions allow a tropical cyclone to form and intensify? - How do easterly waves, the Coriolis effect, the Bermuda-Azores High, steering winds, the jet stream, and the NAO influence cyclone development and tracks? - How do the stages of extratropical cyclone development relate to warm, cold, stationary, and occluded fronts? - Where are tropical and extratropical cyclones most common, and why? - How do storm surge, wind, heavy rain, coastal erosion, and inland flooding differ as cyclone hazards? - Why is storm surge especially dangerous, and how do tides, coastline shape, water depth, and storm position affect it? - How can cyclones trigger flooding, landslides, debris flows, tornadoes, blizzards, and coastal erosion? - What natural service functions do cyclones provide? - How do coastal development, dune removal, seawalls, building practices, population growth, and sea-level rise affect cyclone risk? - How do satellites, aircraft, radar, buoys, ships, models, LIDAR, SLOSH, and ADCIRC support forecasting? - How do a watch and a warning differ, and what actions should follow each? - How do evacuation, shelters, building codes, flood maps, insurance, buyouts, and natural buffers reduce risk? - What do Katrina and Sandy show about forecasting, infrastructure, risk perception, social vulnerability, and preparedness? ## Practice Questions 1. Define cyclone, tropical cyclone, extratropical cyclone, tropical disturbance, tropical depression, tropical storm, hurricane, and typhoon. 2. Compare tropical and extratropical cyclones by location, core temperature, energy source, and weather fronts. 3. Explain how hurricanes are named and classified. 4. Describe the four conditions required for tropical cyclone development. 5. Explain how latent heat released in rain bands and the eyewall fuels a hurricane. 6. Describe the eye, eyewall, rain bands, and hot towers. 7. Explain how the Coriolis effect, steering winds, and the Bermuda-Azores High influence hurricane tracks. 8. Describe how positive and negative NAO conditions affect the jet stream and storm tracks. 9. Explain how an extratropical cyclone develops along a front and eventually dissipates. 10. Describe the comma-cloud pattern, conveyor belts, and dry slot in an extratropical cyclone. 11. Identify major regions at risk for tropical and extratropical cyclones in North America and around the world. 12. Explain how storm surge forms and why it can be higher in a bay, on a shallow coast, or at high tide. 13. Compare coastal surge damage, wind damage, and inland flood damage. 14. Explain how cyclones create overwash deposits and washover channels. 15. Trace links between cyclones, coastal erosion, flooding, landslides, tornadoes, snowstorms, and climate change. 16. List the natural service functions of cyclones. 17. Explain how coastal development, dune removal, seawalls, and building materials can increase risk. 18. Describe the tools used to forecast cyclone track, intensity, rainfall, and storm surge. 19. Distinguish a hurricane watch from a hurricane warning and list appropriate actions for each. 20. Describe personal and community adjustments that reduce cyclone-related deaths and damage. 21. Use Katrina or Sandy to explain how forecasts, infrastructure, population exposure, evacuation, and risk perception shape cyclone losses. ## Quick Review Checklist Before the quiz or test, make sure you can: - distinguish tropical from extratropical cyclones; - define cyclone intensity and compare tropical depressions, tropical storms, hurricanes, and typhoons; - interpret the Saffir-Simpson scale and recognize that it is based on sustained wind speed; - explain how easterly waves and tropical disturbances develop; - list the ocean, atmospheric, wind-shear, and Coriolis conditions required for hurricanes; - explain the function of the eye, eyewall, rain bands, and hot towers; - describe how the Bermuda-Azores High, steering winds, Coriolis effect, jet stream, and NAO influence cyclone tracks; - describe the stages of extratropical cyclone development and dissipation; - explain the Pineapple Express and atmospheric rivers; - locate major hurricane and extratropical cyclone risk regions; - describe storm surge, wind, rainfall, coastal erosion, overwash, and inland flooding; - explain why the right-forward quadrant and landfall at high tide can increase danger; - connect cyclones with floods, landslides, debris flows, tornadoes, snowstorms, and coastal erosion; - describe how cyclones provide water, transfer heat, and renew ecosystems; - explain how development, infrastructure, population growth, and climate change affect cyclone risk; - describe satellite, aircraft, radar, buoy, ship, and computer-model contributions to forecasting; - explain the roles of LIDAR, SLOSH, and ADCIRC in storm-surge prediction; - distinguish watches from warnings and describe how to respond; - list community and personal cyclone adjustments, including evacuation preparation; and - use Katrina and Sandy to explain how science and human decisions affect cyclone losses.