thunderstorms and severe weather

  1. What are the characteristics of a thunderstorm?
    • cumulonimbus cloud with lightning and thunder
    • often heavy rain and gusty winds
    • some have hail or tornadoes
    • average cell - 15 mi in diameter lasting 30 min
    • multicell clusters are most common
  2. What characterizes a severe thunderstorm?
    • wind > 58 mph
    • hail > 3/4 inch
    • generates a tornado
  3. What conditions cause a severe thunderstorm?
    • daily heating
    • squall line from a front
    • dryline
    • sea breeze convergence
    • outflow boundary
  4. What are the hazards associated with thunderstorms?
    • hail
    • wind
    • lightning
    • tornadoes
    • flooding
  5. How much lightning is cloud to cloud?
  6. How hot can lightning be?
    54,000 degrees F (air)
  7. How many get killed in the US every year by lightning/injured?
    • kills 100 per year
    • injures 300 per year
  8. How does lightning form?
    • large electrical charge imbalance
    • upper cloud has + charge
    • lower cloud has - charge
    • charge is induced below thunderstorm on ground
    • stepped leader of ionized air branches downward
    • spark jumps from tall object to stepped leader
    • flowing electrons create return stroke
  9. What do you do and what do you avoid when caught outside in a thunderstorm with lightning?
    • avoid contact with metal
    • take cover if at an outdoor event
    • don't be the tallest point around
    • don't huddle with other people, spread out
  10. How are buildings protected from lightning strikes?
    lightning rods thanks to Ben Franklin
  11. How can lightning kill you indoors?
    • on a corded, landline telephone
    • typing on a desktop computer
    • taking a shower or bath
    • near an open window, opening, or on the porch
  12. How is risk from thunderstorms mitigated?
    • forecasting:  doppler radar
    • predicting:  watches and warnings
    • construction:  windproofing, community shelters
    • personal actions:  NOAA radio, prepared safe room
  13. What are other hazards from weather and their risks?
    • blizzards: extremely low visibility, wind chill effect and frostbite
    • fog: extremely low visibility, smog and vog even worse
    • ice storms: ice accumulates destroying utility lines and trees, travel not possible
    • drought: crops fail, food shortages
    • dust storms: widespread roof and tree damage, contribute to wildfires
    • heat waves: heat stress, dehydration
  14. How do humans exacerbate these weather hazards?
    • flooding
    • urban heat island
    • global warming
  15. Mesoscale Convective System (MCS)
    large, circular, long-lived and interacting group of thunderstorms
  16. linear belts
    • squall line
    • a line of thunderstorms
  17. mammatus clouds
    cellular pattern of pouches hanging underneath the base of a cloud
  18. stepped leader
    a channel of ionized air that approaches the earth in a series of nearly invisible bursts
  19. fulgerite
    natural hollow glass tubes formed in sand or soil when lightning strikes
  20. superbolt
    • positively charged
    • originates from top of cloud
    • 3 to 100 times more powerful than regular lightning
  21. lightning crouch
    last resort way of crouching if you are in lightning prone area
  22. 30:30 rule
    • take shelter when flash to bang is less than 30 seconds
    • remain in safe place for 30 min after hearing last thunder
  23. National Weather Service
    a branch of NOAA that is responsible for weather forecast and preparation of weather maps
Card Set
thunderstorms and severe weather
GEOL 1301 Review Topics for Exam III