1. Thunderstorms & Tornadoes
  2. Thunderstorms
  3. Life cycle of a thunderstorm
  4. Cumulus stage

(a) air rises (updraft) forming a cumulus cloud

(b) updraft keeps precipitation from reaching the ground

  • Mature stage

(a) eventually precip is heavy enough to fall thru updraft & hit ground, producing a downdraft

  • Dissipating stage

(a) downdraft weakens the updraft, cutting off moist air rising to the cloud

(b) cloud begins to evaporate

  1. Form mainly along fronts – may last for days
  2. Lightning: discharge of electricity from a thundercloud to the ground, from cloud to cloud, or within the cloud
  1. Tornado: violently rotating column of air that usually touches the ground
  2. Formation
  3. rotating updraft of air can rotate
  4. mesocyclone: spinning column formed by rotating updraft
  5. eventually, mesocyclone can touch ground & make tornado
  6. Fujita Tornado Intensity Scale
  7. F0 – weakest, causes minor damage
  8. F5 – most violent, can lift & transport sturdy buildings
  9. Predicting
  10. Conventional radar can show ‘hooks’ of precipitation within strong thunderstorms, but sometimes only shows hook once tornado hits ground – TOO LATE!
  11. Doppler radar can show rotation within the clouds giving up to 20 minutes warning before tornado forms
  12. Storm or tornado watches & warnings
  13. Watch: when there is a CHANCE of severe weather
  14. Warning: when there is severe weather currently happening
  1. Hurricanes & Winter Storms
  2. Hurricane: large rotating storm of tropical origin with sustained winds of at least 119 km/hr or 74 mph; very LOW pressure system
  3. Formation
  4. Need a supply of warm, moist air – usually equatorial ocean – so weaken & die if hit cold water or go on land
  5. Something happens to heat air in specific point, so it rises & forms a low
  6. If it begins rotating, can form a hurricane
  7. Characteristics
  8. Eye: extremely low pressure center of the hurricane; air sinks here, so no clouds & very calm
  9. Eye wall: ring of violent thunderstorms around the eye; strongest wind & rain are here
  10. Hurricane classified by wind speed, from tropical depression to tropical storm to hurricane
  11. Effects
  12. Storm surge: large wave of water caused by a low-pressure system
  13. High winds create large waves to damage coast & cause flooding
  14. Worst damage happens to right of hurricane in N hemp, because wind blows counterclockwise around the low, so the strongest winds are on the right
  15. Saffir-Simpson scale
  16. Category 1: minor hurricane, 74-95 mph wind, minimal damage
  17. Category 5: catastrophic hurricane, >155 mph wind, buildings destroyed & full evacuation, catastrophic damage
  18. Winter storms
  19. Blizzard: winter storm with high winds, low temps (<-7C) & snow
  20. Nor’easter: low pressure system along East coast that blows strong winds from the northeast; not cold enough for a blizzard, but very strong winds & damage


I.Climate Change (Greenhouse effect)

a.Greenhouse gasses like carbon dioxide, methane & water vapor are produced by burning fossil fuels

b. High-energy radiation from the sun enters the atmosphere, but low-energy radiation leaving Earth is trapped by the greenhouse gases, keeping the heat in & increasingaverage global temperatures.

II.Ozone Layer

a.Located in the stratosphere & protects us from ultraviolet radiation

b.Chemicals from aerosols & air conditioners, called chlorofluorocarbons (CFCs) are low-density, so float up to the ozone layer, reacting with it, allowing UV radiation through to Earth’s surface