Hazardous Weather ND Test 2

  1. What is a drought?
    prolonged period of dry weather that dramatically lowers the water level
  2. What are droughts caused by?
    high pressures
  3. What is desertification?
    • process that turns productive desert into non-productive desert as a result of poor land management
    • occurs in semiarid areas bordering deserts
  4. What causes desertification?
    • overgrazing
    • cultivating of marginal lands
    • destruction of vegetation in arid regions
    • poor grazing management
    • incorrect irrigation processes
    • increasing human population and poverty
  5. What are heatwaves?
    • long periods of extreme heat that are longer and hotter than normal
    • close to the ground so they affect humans, pets and vegitation
  6. What are ice storms?
    • caused by freezing rain
    • rain turns into ice on contact, causing everything to be slippery and causes extra weight on power lines and roofs
  7. What are the 3 conditions for freezing rain?
    • source of moisture
    • warm air over a layer of cold air
    • ground temperatures at or below freezing
  8. What are blizzards?
    severe winter storms with large amounts of snow, high winds, and low visibility for extended periods of time
  9. What causes blizzards?
    interaction between upper level low pressure trough and surface low pressure
  10. What causes Colorado & coastal storms?
    moist ocean air
  11. What causes Alberta Clippers?
    dry air with less snow and cold temperatures
  12. What causes Nor'easters?
    hurricane winds, heavy snows, intense precipitation, high waves
  13. What are the atmospheric conditions for a thunderstorm?
    • warm, humid air in the lower atmosphere
    • cold air above warm air
    • updraft must force air into the upper atmosphere
  14. What are the different stages in a thunderstorm?
    • cumulus stage
    • mature stage
    • dissipative stage
  15. What is required to be a severe thunderstorm?
    • winds greater than 58 mph
    • hailstones bigger than .75"
    • or generates a tornado
  16. What are the necessary conditions for a severe thunderstorm?
    • greater wind sheer, greater storm
    • high water vapor content in lower atmosphere
    • updraft of air
    • dry air mass above a moist air mass
  17. What are the types of severe thunderstorms?
    • MCSs (mesoscale convective systems) most common
    • squall lines
    • supercells
  18. What are MCSs?
    large clusters of self-propagating storms
  19. What are squall lines?
    • long lines of individual storm cells
    • anvil shaped clouds form
    • can develop along drought lines
  20. What are supercells?
    • smaller than other two but more damaging
    • spawn the most tornadoes
    • 12-30 miles in diameter
    • last between 2 and 4 hours
  21. What are tornadoes?
    vortex extending downward from the cloud and touching the ground
  22. Where do tornadoes form?
    form where there are large differences in atmospheric pressure over short distances
  23. What are the three stages of a tornado?
    • organizational stage
    • mature stage
    • shrinking stage
    • rope stage
  24. What occurs in the organizational stage?
    • updrafts tilt horizontally, rotating the air vertically
    • cloud begins to lower and funnel descends
  25. What occurs in the mature stage?
    • funnel extends to ground
    • moist air is drawn up
    • suction and damage occur
  26. What occurs in the shrinking stage?
    • warm air is reduced
    • tornado begins to thin
  27. What occurs in the rope stage?
    funnel moves erratically and then disappears
  28. What is the Fujita scale?
    • measures internal windspeeds and damage produced
    • measured F0 to F5
    • updated in 2007
    • now based on detailed wind measurements and long-term damage records
Card Set
Hazardous Weather ND Test 2
test 2