Hazards Final
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- What is an air mass?
- A mass of air with the same temperature and humidity
- What are the different types of air masses?
- cP, mP, cT, mT
- What direction does a midlatitude cyclone normally rotate? What is the pressure like in a cyclone?
- Counterclockwise; low
- What direction does the air travel in a cyclone?
- Upwards
- What part of the jet stream is a cyclone associated with?
- Trough
- How does a cold front produce unstable air?
- Cold air pushes warm air up and forms clouds
- What is unstable air?
- Air that does not resist vertical displacement
- How does a nor'easter, blizzard, or icestorm move up the NE US coast?
- The counterclockwise rotation comes from the north, the eastern side picks up moisture from the Atlantic which feeds the cyclone
- What are the characteristics of a blizzard?
- Cold winds, less than 20 degrees, zero visibility
- Explain how thunderstorms work
- Warm buoyant air rises and condenses to form clouds. As the vapor condenses, it releases latent heat which makes the air warmer and therefore it rises higher. Cool air then makes is dissipate
- Where are straightline winds found? What are they called?
- In front of the storm, gust front
- Where do thunderstorms primarily occur?
- Plains states and Florida
- Where is hail most frequent?
- The plains states
- How does lightning work?
- Areas of excess positive charge seek negative charges. Bottom of the storm cloud is negative, top is positive
- Where is lightning most frequent?
- Texas, Florida, North Carolina
- List lightning safety points
- Seek shelter as soon as you hear thunder or see lightning, don't touch anything electrical (plumbing, water, phone), get in a non-convert. car and dont touch anything, move to a low place and crouch on the balls of your feet
- What 3 conditions do you need for a tornado?
- Northerly flow of mT air from the Gulf that is humid and 75+ degrees, cold, dry air from Canada at 50+mph, easterly jet stream winds at 150+ mph
- What time of the year do tornados form?
- Spring and Summer
- What does the F-scale measure?
- Wind speed and damage
- List tornado safety points
- take shelter during a warning, dont open windows and stay away from them, go to a basement or bathtub, stay on the northeast side of the shelter, get in a ditch, stay out of cars and mobile homes
- What is a hurricane?
- Large tropical cyclones that convert ocean heat into wind and waves
- Where do hurricanes come from?
- West coast of Africa, 20 degrees above the equator
- How does a hurricane develop?
- Low pressure zones of thunderstorms and weak winds create a disturbance. Stronger winds turn it into a depression. Warm air rises, cools, condenses-latent heat. Extra heat increases updrafts. More than 39 mph, storm, >74=hurricane
- What is the difference between a distrubance and a storm?
- A storm has rotational value
- Requirements for a hurricane
- 80 degrees in upper 200ft of ocean, atmosphere cool fast enough with high to make it unstable, thunderstorms maintained, 300mi away from equator, coriolis to maintain low pressure, pre existing near surface convergence of rotating moist air, weak upper level winds blowing the same direction as the storm
- What is a hurricane called in Japan/China? India/Africa?
- Typhoon, Cyclone
- When and where do hurricanes occur?
- May-Dec around the Bermuda high
- What causes a hurricane to change its path?
- Areas of high pressure, large air masses, upper level winds
- Why are barrier islands dangerous?
- Get hit by flood and ebb
- How does damage occur?
- intensity, duration, angle at which the hurricane approaches land, population density
- How can damage be reduced?
- warnings/evacuations, maintain beach width and dune height, floodwalls, construction code enforcement, zoning for land use
- What do streams do?
- Carry water from land to sea, carry sediment, dissolve materials into ions, erosion
- How do streams balance variables it deals with?
- Changes dischange, available sediment, gradient, and channel pattern accordingly
- What does the cross-sectional shape have to do with discharge?
- larger cross section=greater discharge
- What causes meandering?
- too much discharge-uses its energy by cutting the banks
- What does too much load do to a stream?
- Braided streams, levees
- What is lag time?
- time difference between heavy rains and peak discharge in stream draining area
- regional floods
- rainfall for days
- landslide flood
- landslide, log jam, or lahar dams fail
- Why are flash floods dangerous primarily?
- transport large items, erosion, water damage, death, health hazards
- Secondary dangers
- service disruption, polluted water, food shortage
- Tertiary dangers
- channel location change, farms destroyed, lost jobs, insurance rate increase, corruption w/relief funds, wildlife habitat destruction
- Societal responses to floods
- structural, non-structural
- Effects of channelization
- decreases cross section and increases flooding
- effects of subsidence
- compaction causes pooling water and changes drainage pattern
- Effects of storm sewers
- collect runoff and block infiltration, decrease lag time, increase peak discharge of collection streams
- Effects of urbanization
- reduction of infiltration, decreased lag time, increase in peak discharge (flash floods)