Chapter 7: Atmospheric
Disturbances
McKnight’s Physical Geography:
A Landscape Appreciation,
Tenth Edition, Hess
Physical Geography
Lecture Outline 28
Localized Severe Weather
Physical Geography: A Landscape
Appreciation 10e
2
Thunderstorms
– Violent convective storms with thunder and lightning
– Causes:
• Unstable Air and
Convection
• Clashing Ai...
Where would you expect the
most thunderstorms?
Physical Geography: A Landscape
Appreciation 10e
4
18%
0%
0%
82% 1. Mid-lat...
Thunderstorms by Latitude
5© 2011 Pearson Education, Inc.
Causes of Thunderstorms
• Convection of Unstable Air
• Convergence
• Clashing of Air Masses
© 2011 Pearson Education, Inc....
Which state would you expect to
have the most T-storms?
Physical Geography: A Landscape
Appreciation 10e
7
9%
9%
0%
9%
0%
...
8© 2011 Pearson Education, Inc.
Stages in Formation
9
Physical Geography: A Landscape
Appreciation 10e
10
Figure 7-29
• Lightning
– Electric discharge
– Separation of charges due
to friction with ice particles
– Release of el...
DANGERS
Lightning
Hail
Tornadoes
Winds
Flash flooding
Lightningphotos: noaa
Hail
Down drafts
Flash Flooding
Physical Geography: A Landscape
Appreciation 10e
16
Thunderstorm Safety
• Take cover, stay there!
• Building is best. Car is 2nd (don’t touch
metal)
• Don’t BE or be UNDER th...
Tornadoes
Physical Geography: A Landscape
Appreciation 10e
18
Is a tornado a low or high
pressure system?
Physical Geography: A Landscape
Appreciation 10e
19
18%
9%
73% 1. Low
2. High
...
Tornadoes
• Tornadoes
– Small, intense cyclonic
storm (<400 meters across)
– Lowest central pressures,
very steep pressure...
Physical Geography: A Landscape
Appreciation 10e
21
Tornado formation
– Vertical wind shear creates horizontal rotation
– Tilted into vertical by thunderstorm updraft
– Mesoc...
Causes:
• Unstable air from clashing air masses
• Unstable air from convection or
convergence
Physical Geography: A Landsc...
If cP air meets mT air, which will
rise?
Physical Geography: A Landscape
Appreciation 10e
24
0%
0% 1. cP
2. mT
If mT air meets cT air, which will
rise?
Physical Geography: A Landscape
Appreciation 10e
25
0%
0% 1. mT
2. cT
Which type of front will most
likely have a tornado?
Physical Geography: A Landscape
Appreciation 10e
26
0%
0%
0% 1. Warm ...
27© 2011 Pearson Education, Inc.
Physical Geography: A Landscape
Appreciation 10e
28
Locations in US
• Tornado Alley
– clash between cP and mT
– Dry Line – cT meets mT
• Florida
– Convergence, Hurricanes, Co...
Tornado Wind Patterns
Dangers
• Winds!!!!!
• Flying debris
Flying Debris
Watch vs. Warning
• Watch - Conditions are conducive to the
development of tornadoes in and close to
the watch area.
• War...
Danger signs
• Strong, continuous rotation in clouds
• Whirling dust and/or debris on ground beneath
cloud layer
• Hail or...
Tornado Safety
• Mobile home or vehicle
– GET OUT and
AWAY!!
• Basement is best
• Or……under a stairwell
or in windowless r...
Tornado classification
36
37© 2011 Pearson Education, Inc.
Greensburg,
Kansas
2007
Physical Geography: A Landscape
Appreciation 10e
38
Joplin, Missouri- Spring, 2011
Physical Geography: A Landscape
Appreciation 10e
40
Topeka, Kansas, Spring 2011
Physical Geography: A Landscape
Appreciation 10e
41
• Tuscaloosa, AL 4/27/2011
• 1 minute raw footage – Tuscaloosa
• Joplin, MO 5/22/2011
• http://www.youtube.com/watch?
feat...
Why so many tornadoes
reported recently?
• More reporting and pictures captured!
• Many reported twice
• More people = mor...
Pg tp-class28-localized severe weather
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Transcript of "Pg tp-class28-localized severe weather"

  1. 1. Chapter 7: Atmospheric Disturbances McKnight’s Physical Geography: A Landscape Appreciation, Tenth Edition, Hess
  2. 2. Physical Geography Lecture Outline 28 Localized Severe Weather Physical Geography: A Landscape Appreciation 10e 2
  3. 3. Thunderstorms – Violent convective storms with thunder and lightning – Causes: • Unstable Air and Convection • Clashing Air Masses and Cold Fronts • Convergence 3
  4. 4. Where would you expect the most thunderstorms? Physical Geography: A Landscape Appreciation 10e 4 18% 0% 0% 82% 1. Mid-latitudes 2. Polar Regions 3. Equatorial Regions 4. At the Sub-Tropical High
  5. 5. Thunderstorms by Latitude 5© 2011 Pearson Education, Inc.
  6. 6. Causes of Thunderstorms • Convection of Unstable Air • Convergence • Clashing of Air Masses © 2011 Pearson Education, Inc. 6
  7. 7. Which state would you expect to have the most T-storms? Physical Geography: A Landscape Appreciation 10e 7 9% 9% 0% 9% 0% 73% 1. Florida 2. Missouri 3. Colorado 4. Vermont 5. Oregon 6. New York
  8. 8. 8© 2011 Pearson Education, Inc.
  9. 9. Stages in Formation 9 Physical Geography: A Landscape Appreciation 10e
  10. 10. 10 Figure 7-29 • Lightning – Electric discharge – Separation of charges due to friction with ice particles – Release of electrons – Lightning types • Cloud to ground • Cloud to cloud • Within cloud – Thunder
  11. 11. DANGERS Lightning Hail Tornadoes Winds Flash flooding
  12. 12. Lightningphotos: noaa
  13. 13. Hail
  14. 14. Down drafts
  15. 15. Flash Flooding
  16. 16. Physical Geography: A Landscape Appreciation 10e 16
  17. 17. Thunderstorm Safety • Take cover, stay there! • Building is best. Car is 2nd (don’t touch metal) • Don’t BE or be UNDER the highest point • Crouch on toes if out in open • 5 second difference in lightning + thunder arrival = 1 mile away Physical Geography: A Landscape Appreciation 10e 17
  18. 18. Tornadoes Physical Geography: A Landscape Appreciation 10e 18
  19. 19. Is a tornado a low or high pressure system? Physical Geography: A Landscape Appreciation 10e 19 18% 9% 73% 1. Low 2. High 3. Depends upon the individual storm
  20. 20. Tornadoes • Tornadoes – Small, intense cyclonic storm (<400 meters across) – Lowest central pressures, very steep pressure gradient – Fast winds, up to > 300 mph – vapor and debris 20 Figure 7-30
  21. 21. Physical Geography: A Landscape Appreciation 10e 21
  22. 22. Tornado formation – Vertical wind shear creates horizontal rotation – Tilted into vertical by thunderstorm updraft – Mesocyclone and tornado development 22
  23. 23. Causes: • Unstable air from clashing air masses • Unstable air from convection or convergence Physical Geography: A Landscape Appreciation 10e 23
  24. 24. If cP air meets mT air, which will rise? Physical Geography: A Landscape Appreciation 10e 24 0% 0% 1. cP 2. mT
  25. 25. If mT air meets cT air, which will rise? Physical Geography: A Landscape Appreciation 10e 25 0% 0% 1. mT 2. cT
  26. 26. Which type of front will most likely have a tornado? Physical Geography: A Landscape Appreciation 10e 26 0% 0% 0% 1. Warm front 2. Cold front 3. Stationary front
  27. 27. 27© 2011 Pearson Education, Inc.
  28. 28. Physical Geography: A Landscape Appreciation 10e 28
  29. 29. Locations in US • Tornado Alley – clash between cP and mT – Dry Line – cT meets mT • Florida – Convergence, Hurricanes, Convection • Other Locations – Convection, Cold Fronts Physical Geography: A Landscape Appreciation 10e 29
  30. 30. Tornado Wind Patterns
  31. 31. Dangers • Winds!!!!! • Flying debris
  32. 32. Flying Debris
  33. 33. Watch vs. Warning • Watch - Conditions are conducive to the development of tornadoes in and close to the watch area. • Warning - tornado has been sighted by spotters or indicated on radar and is occurring or imminent in the warning area.
  34. 34. Danger signs • Strong, continuous rotation in clouds • Whirling dust and/or debris on ground beneath cloud layer • Hail or heavy rain followed by extreme shifts in wind • Loud, continuous rumble which doesn't fade over time • Bright, blue-green flashes near the ground of power lines breaking • Lowering of the clouds in a spiraling fashion • Funnel cloud not moving toward left or right
  35. 35. Tornado Safety • Mobile home or vehicle – GET OUT and AWAY!! • Basement is best • Or……under a stairwell or in windowless room or bathtub • Cover yourself
  36. 36. Tornado classification 36
  37. 37. 37© 2011 Pearson Education, Inc.
  38. 38. Greensburg, Kansas 2007 Physical Geography: A Landscape Appreciation 10e 38
  39. 39. Joplin, Missouri- Spring, 2011 Physical Geography: A Landscape Appreciation 10e 40
  40. 40. Topeka, Kansas, Spring 2011 Physical Geography: A Landscape Appreciation 10e 41
  41. 41. • Tuscaloosa, AL 4/27/2011 • 1 minute raw footage – Tuscaloosa • Joplin, MO 5/22/2011 • http://www.youtube.com/watch? feature=endscreen&v=VQDkmziz1n8&NR =1 Physical Geography: A Landscape Appreciation 10e 42
  42. 42. Why so many tornadoes reported recently? • More reporting and pictures captured! • Many reported twice • More people = more people impacted • More people living in urban areas – when they are hit, many are impacted • 2011 was A particularly violent year – favorable atmospheric conditions • Climate change? Physical Geography: A Landscape Appreciation 10e 43
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