Geo ch.11

How many people are in ZIP codes where there are most of the losses of natural disasters?

About 90% of the total losses occurred in ZIP codes that contain less than 20% of the national population.

Where does the sediment eroded from a beach during inundation go?

Alongshore where it is lost from local rebuilding of barrier beach (may build beach somewhere else) Landward where it goes into rebuilding barrier beach (washover deposits) Offshore where it might be moved back onto barrier beach at some later time

How is rising relative sea level influencing coastal flooding?

As the sea rises, the frequency of flooding in coastal cities and towns during high tides and minor rainstorms is also increasing.

What is atmospheric circulation fueled by?

Atmospheric circulation is fueled by energy from the sun and its unequal heating of Earth's surface.

What can sedimentary deposits show?

Can preserve a record of many hurricane washover features. Core taken from the deposits can reveal hurricane units buried in the subsurface.

What does National Flood Insurance Program do?

Covers flooding (including inundation by storm surge and waves)

Where does the Coriolis effect defect fluid and ocean in the atmosphere based on hemisphere?

Defects to the right in the northern hemisphere and to the left in the southern hemisphere.

What is used to estimate hurricane activity?

Geologists use preserved sedimentary deposits to estimate hurricane activity over thousands of years.

What is the mandatory SRL (Severe Repetitive Loss) buyout program and what are the objectives?

Harris County Disaster Recovery Post Disaster Relocation and Buyout Program The objectives are: To acquire properties that have been subject to multiple floods and use for public space, green space, and/or flood control measures (including restoring floodplains to their natural and beneficial function, aiding in the storage of floodwaters). To assist homeowners and businesses to move to an area with a reduced risk of flooding. To eliminate future flood damages and health and safety risks for owners and rescuers.

What does fortified to Gold-level designation include?

House's roof, floors and foundation are fastened together with steel straps; windows are made of impact resistant glass; and roof is specifically sealed and nailed down.

What hurricane-defensive features should be incorporated into houses built near the Atlantic and Gulf of Mexico coastlines?

Houses built on or near beach must be able to withstand high wind speeds and overwhelming storm-surge water flow. A house must rest on vertical pilings 3 to 10 m (10 to 30 ft) deep. It must be elevated 2 to 8 m (6.5 to 26 ft) above land level so storm water can flow underneath. Pilings and house must be bound together by horizontal steel beams held by steel bolts. Roof, roof rafters, and walls must be securely tied together. Strap roofs to walls. Add numerous hurricane straps to help hold the roof to the walls. Ban the common practice of using rapid-fire staples to secure thin asphalt roofing sheets onto plywood roofs. Buildings should not have eaves or overhangs so wind lift is reduced. Builders should eliminate or strengthen eaves that project out from roofs, thus making it harder for winds to lift off roofs. Exterior boards should be large, heavy, and securely fastened to reduce wind ripping. All exterior glass windows and sliding-glass doors should be made of shatterproof glass or be protected by shutters. If the building does not have built-in shutters, plywood should be precut to fit over all windows and sliding-glass doors. Eliminate potential debris.

How high can surges be?

In the Northern Hemisphere, maximum storm surges occur about 15 to 30 km (10 to 20 mi) to the right of the path of the eye. The highest water levels occur to the right of the hurricane eye where the winds are the strongest and the storm surge can get as high as 23 feet.

What do individual states coordinate insurance for?

Individual states coordinate insurance against damage from high winds, hail (and wildfire).

When hurricanes come ashore, which area receives the highest wind speed and storm surge--the right side or left side of the eye?

On the left-hand side, the winds come off the land, while on the right-hand side, the winds come off the ocean, pushing much more seawater onto the land. The highest water levels occur to the right of the hurricane eye where the winds are the strongest. If you're on the right-hand side of the tropical cyclone, you experience the speed of the storm plus the winds speeds. If you are on the left-hand side, you feel the wind speed minus the storm motion.

Tx coast wind directions:

Onshore directed (to right of eye) Shore-parallel ( in front of eye) Offshore directed (to left of eye)

What are the styles of coastline inundation, also called Overwash?

Overwash of barrier beach by wave runup and by storm surge

What is the probability for a hurricane hitting an individual county along the Gulf-of-Mexico coast?

Ranges between 15% and 5% per year.

What is rapid intensification? What problems does it present for people living near the coast?

Rapid intensification is defined as a wind-speed increase of 35 mph or higher within 24 hours. The hurricanes will intensify through the point of landfall and hit underprepared people harder then they expect. Rapid intensification is expected to become more common and more intense through this century as th4e global climate and seawater continue to warm. This presents increased problems, including reduced evacuation times, especially for coast cities.

What does mitigation require?

Requires reducing exposure and vulnerability. Exposure: people and infrastructure located in hazard-prone area Vulnerability: Possibility of being negatively impacted by a natural hazard.

Whats examples of traditional or structural coastal adaptations?

Sandbags Local levees at High risk Priority Areas Home elevation at High Risk Priority Areas

Draw a cross-section showing how a hurricane produces a sea surge that floods the land.

Sea level rises for several reasons: Winds from the approaching storm push sea swells ashore that pile water above the normal tidal levels, especially near and to the right of the landfalling eyewall Then the arrival of the hurricane brings the storm surge, which is a relatively rapid rise in water level caused by seawater flowing onshore. Seawater builds up beneath the eye because it is a low-pressure zone. About 95% of the seawater that surges ashore is wind-driven The highest water levels occur to the right of the hurricane eye where the winds are the strongest. On top of the already elevated sea level come the large waves blown by the hurricane winds. The astronomical tides raise and lower the sea levels each day. The worst time for a storm surge to come onshore is during the already high sea level of an astronomical high tide.

What is erosive return-flow channels?

Some coastal erosion can also be associated with water flowing back into Gulf.

What are the Big Three Hazards brought by hurricanes?

Storm Surge, inland flooding, and wind.

Do hurricanes in the Northern Hemisphere rotate clockwise or counterclockwise?

The Coriolis effect is the mechanism that spins the storm in a counterclockwise (cyclonic) rotation around a central core in the Northern Hemisphere.

What role does the Coriolis effect play in hurricane formation?

The Coriolis effect is the mechanism that spins the storm in a counterclockwise (cyclonic) rotation around a central core in the Northern Hemisphere. Approaching the Western Hemisphere, Cape Verde-type Hurricanes commonly move north on clockwise-curving paths due to the Coriolis effect. As a hurricane moves poleward, the Coriolis effect strengthens. Hurricanes do not form along the equator because there the Coriolis effect is zero. Even an already-formed hurricane could not cross the equator because without the Coriolis effect it would lose its rotation.

What is nuisance flooding and what problems can it cause?

Nuisance flooding is low levels of inundation that do not pose significant threats to public safety or cause major property damage, but can disrupt routine day-to-day activities and put added strain on infrastructure systems. Analysis suggests nuisance flooding in response to sea-level rise could generate property value exposure comparable to, or larger than, extreme events.

What factors control the path of a Cape Verde-type hurricane from Africa to North America?

These Cape Verde-type hurricanes are influenced by the size and position of a high-pressure zone, the Bermuda High. A small Bermuda High allows hurricanes to stay over the Atlantic Ocean and miss North America. A large Bermuda High may guide hurricanes along the eastern coast to the United States and Canada. When the Bermuda High moves south, it may direct hurricanes into the Caribbean Sea and Gulf of Mexico.

What is the difference between a hurricane, a typhoon, and a cyclone? Where in the world does each occur?

They are all large, tropical cyclonic storms with wind speeds exceeding 119 km/hr (74 mph). The typhoons of the northwest Pacific Ocean hit Japan, China, and the Philippines about three times as often, and the storms can be stronger. In the United States, we know these storms as hurricanes, but they go by cyclones in the Indian Ocean and typhoons in the western Pacific Ocean.

Where do the highest water levels occur in a hurricane?

To the right of the hurricane eye in northern hemisphere (location of onshore-directed winds + highest wind speeds).

Where are tornadoes most likely to form in a hurricane?

Tornadoes most commonly form in the right-front quadrant of the hurricane in outer rain bands some 80-500 km (50-300 mi) from the hurricane center. Tornadoes are most likely to form in hurricanes that are : large, intense and strongly curving; moving forward at 12-30 km/hr (8-18 mph); interacting with old, weakened fronts; and over land.

Why do hurricanes strike the East Coast of Canada and the United States but not the West Coast?

Tropical cyclones form on the west sides of oceans where warm water is concentrates, with two informative exceptions. Hurricanes form off the Pacific Coast of Mexico because a bend in the coastline isolates a pool of warm coastal water from the cold California current; it is called the East Pacific Tropical Basin.

Explain the sequence of events that turns an African storm into a hurricane hitting the United States.

Tropical cyclones may form and begin growing toward hurricane status in the waters near the Cape Verde Islands off northwest Africa. Hurricanes may develop from either a preexisting convective storm or, more commonly, from an easterly wave. These Cape Verde-type tropical cyclones are blown westward across the Atlantic Ocean by the trade winds, picking up heat from warm ocean water. Summer is when westward-traveling storms have the opportunity to get well-organized as heat engines using abundant fuel (latent heat) derived from evaporation of sea-surface water to grow into Cape Verde-type hurricanes. Approaching the Western Hemisphere, they commonly move north on clockwise-curving paths due to the Coriolis effect. As a hurricane moves poleward, the Coriolis effect strengthens.

Rank the following in order of increasing strength: hurricane, tropical depression, tropical storm, tropical disturbance

Tropical disturbance: A low-pressure zone that draws in a poorly organized cluster of thunderstorms with weak surface winds Tropical depression: When surface winds strengthen and flow more efficiently around and into the center of the growing storm. Receives an identifying number Tropical Storm: When sustained surface-wind speeds exceed 63 km/hr (39 mph) Hurricane: When surface-wind speeds exceed 119 km/hr (74 mph) and an eye forms

Explain how latent heat helps hurricanes grow

Upon reaching the eyewall, the air rises rapidly, cools, and releases latent heat of condensation that adds to buoyancy and upward velocity. The inward drop in air pressure causes converging air to expand and cool slightly below the sea-surface temperature. This temperature difference generates a flow of sensible and latent heat from the sea into the air in order to reach equilibrium. These ongoing processes allow the air to pick up and store increasing amounts of energy from the sea. This energy is carried up into the eyewall and released to power the hurricane. Latent heat by condensation of water vapor inside a hurricane is its main energy source

Examples of nature-based measures (green infrastructure), from best at Benefit/Cost to lowest

Wetland Restoration at risk reduction priority areas Oyster reef restoration Barrier island restoration Wetland restoration at conservation priority areas Beach restoration east coast Beach restoration west coast

If the speed of forward motion of a hurricane slows, what happens to rainfall amounts at a given site in the hurricane's path?

When a hurricane slows its forward motion it can yield enormous volumes of rain. Slower moving storms can yield heavier rainfalls. Slower moving tropical cyclones carrying more water vapor should produce more heavy rainfall and severe flooding events.

When does a tropical cyclone grow into a large storm?

When its center becomes significantly warmer than the surrounding air.

At what wind speed does a tropical storm become a hurricane?

When surface-wind speeds exceed 119 km/hr (74 mph), a tropical storm has grown strong enough to be called a hurricane and it forms an eye.

Why is the eye of a hurricane so clear?

When surface-wind speeds exceed 119 km/hr (74 mph), none of the wind reaches the center of the storm, resulting in the calmer clear area known as the eye. Air in the eyewall spirals upward and outward. To replace this outflow, cool air aloft sinks into the center of the core up high. As this air descends, it warms adiabatically and absorbs moisture, leaving the core clear and relatively cloud-free, thus forming the eye.

Which atmospheric circulation is the product of Earth's size and angular or rotational velocity?

Zonal circulation (latitudinally constrained Hadley, Ferrel, and Polar cells)

Can a hurricane develop at 0 degrees latitude on the equator?

Hurricanes do not form along the equator because there the Coriolis effect is zero. Even an already-formed hurricane could not cross the equator because without the Coriolis effect it would lose its rotation. The Coriolis effect is so weak within 5 degrees north or south of the equator that there is not enough rotation to build hurricanes.

What are the most common months for hurricanes to strike Canada and the United States? Why?

Hurricanes form when sea-surface temperatures are warmest; in the North Atlantic Ocean, this occurs in late summer. But sea-surface temperatures are highest at the end of summer because the ocean water with its high-heat capacity keeps absorbing solar energy all summer long. Hurricanes in the United States occur in abundance in September.

Compare a tornado to a hurricane. Which has the most total energy? Which has the highest wind speeds?

Hurricanes have more energy and last longer. Tornadoes have higher wind speeds though, higher than any other wind phenomenon.

Draw a map and explain how easterly waves or tropical waves become tropical cyclones.

Hurricanes may develop from either a preexisting convective storm or, more commonly, from an easterly wave. Easterly waves or tropical waves are disturbances or mega-ripples that develop within the trade winds: they are elongate, north-south oriented, and extend 2,000 to 3,000 km (1,200 to 1,900 mi). On the east side of the wave axis, the low-level winds converge and rise, forming clouds with rain. On the west side of the axis, the upper-level winds diverge and sink, resulting in clear skies. The instabilities in the atmosphere created by the easterly waves lead to tropical disturbances that sometimes become energetic enough to grow into hurricanes as they move to the west. An easterly wave or tropical wave within the trade winds. To the east (right) of an axis, the winds converge and rise, and clouds with rain occur. To the west (left) of an axis, the winds diverge and sink, and clear skies occur.

How does the eyewall replacement cycle work?

In major hurricanes, generally with wind speeds greater then 180 km/hr (11 mph), a narrow or contracting eyewall may be replaced. An outer rain band may strengthen and grow into an organized, circular band of thunderstorms; it effectively becomes an outer eyewall. This outer eyewall may spin into a narrower diameter and move slowly inward, where it can absorb some of the rising moist air that fuels the inner eyewall. The strongest winds are in the inner eyewall, but they may weaken during the replacement as the outer eyewall is becoming the new inner eyewall. After the eyewall replacement is completed, the hurricane may improve its efficiency of operation and re-intensify.

What is the Texas Windstorm Insurance Association (TWIA)?

Insurer of last resort for wind and hail coverage for Texas Gulf Coast residential and commercial property owners. TX state law requires all companies licensed to write property insurance in Texas to be a member of TWIA. TWIA policies cover wind and hail in 14 coastal counties and parts of Harris County for owners who cannot obtain insurance from a licensed company.

What are hurricane and named storm deductibles?

Introduced as a risk-sharing mechanism. policyholders now bear more of the risks, without raising overall premiums to unaffordable levels.

Draw a cross-section through a hurricane and explain how it operates. label the internal flow of winds. Be sure to explain the eye

Low-altitude winds feed moisture and heat to the eye. Updrafts rise rapidly up the core (eye) wall and are helped away by high-altitude winds. Low-level air converges toward the storm center, rises into clouds and rotates up the eyewall, and diverges aloft. The steepest pressure gradient at low levels of the eyewall causes the greatest wind speeds.

What does a long fetch lead to?

Maximized coastal inundation

How do we monitor tropical cyclones?

Meteorological radar emits a pulse and measures the radiation that is scattered and reflected back to the radar instrument by raindrops, snowflakes and hailstones. This data provides an estimate of wind speed, and wind direction, as well as amount of rain, snow, and hail in the air.

What is the role of the Intertropical Convergence Zone (ITCZ) in initiating Caribbean hurricanes?

The ITZC is a major site of convergence of warm, moist, low-level winds that rise high, forming a nearly continuous ring of thunderstorms surrounding the Earth. Occasionally a cluster of thunderstorms breaks away and organizes into a more unified system. Add some rotation to these convective columns and a tropical cyclone is born. Hurricanes commonly form above the very warm waters of the Caribbean Sea. Water warm enough to spawn hurricanes is carried by the Loop Current from the Caribbean Sea, northward between Mexico and Cuba, into the Gulf of Mexico, adding to the hurricane potential there. Above-average temperatures in the seawater between Africa and the Caribbean allow tropical disturbances to gain strength as they are blown westward. Low atmospheric pressure in the Caribbean region aids the formation and development of hurricanes.

Which part of the world is hit by the most tropical cyclones?

The typhoons of the northwest Pacific Ocean hit Japan, China, and the Philippines about three times as often, and the storms can be stronger.

What is the warm core of a hurricane?

The warm core is due to the release of huge quantities of latent heat from rising winds and to adiabatic warming of the sinking air in the eye. Eyes and eye-walls form the warm core of a hurricane. When a hurricane ceases to have warm, moist air flowing up its warm core, it can turn into a cold core and the hurricane body can merge with the colliding weather front.