Weather systems

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Weather systems

  1. 1. Weather systems • Product of air mass characteristics • - and upper air influence • jetstream ( polar, - especially polar) • Violent weather: tornado, hurricanes • /
  2. 2. Mid latitude wave cyclone • 1. Most common system in our region • 2. Here storms move from west to east • 3. Pattern looks like an ocean wave • 4. Components: • warm front, cold front, open system. Ends with an occluded front
  3. 3. MID LATITUDE WAVE CYCLONE
  4. 4. STORM SYSTEMS
  5. 5. Ferrel & Ballots Law • Ferrel discovered the pattern of windflow associated with pressure gradients. • Buys Ballot clarified this with an example – “Sailors Law” In the Northern Hemisphere if you stand with your back to the wind where two pressure systems abut – then the low pressure is on the left hand side.
  6. 6. Ballot’s Law
  7. 7. thunderstorm
  8. 8. microbursts • 1 mile in extent • Winds up to 150-200 miles per hour • Hazard to aviation • Caused by sudden evaporation of fallen precipitation ( or sudden contact with cold air) – cools the air and gives it a burst of speed ( down and divergent flow)
  9. 9. Microburst ( opposite of a tornado)
  10. 10. Photo - microburst
  11. 11. Hurricanes • Where: Develop over oceans 5-30 degrees from equator. • Stages: Easterly flow ( convergence) • Trop. Disturbance: unorganized • Trop. Depression organize( 39mph winds) • Hurricane 75+ mph winds
  12. 12. Hurricane facts • Called cyclone in India/Australia, • N. & S. Pacific typhoon • Philippines Baguio • Same type of storm • - Seasons. Atlantic May-Nov. • S. Hemis. Nov- May
  13. 13. Areas of impact
  14. 14. Descriptions • Extremely low pressure ( record 870 mb) • usually ~950 mb. • Effective energy conversion- takes water from ocean surface, evaporates it rapidly – • latent energy released when forced upwards and condenses ( think vacuum cleaner) • Anatomy: eye, eyewall, bands of outer clouds – creates a storm surge. can last for weeks, extend over 300 miles
  15. 15. Hurricane Floyd - 1999
  16. 16. Hurricane Scales • Saffir-Simpson • 1 75-95 mph • 2 96-110 • 3 111-130 • 4 130-155 • 5 155+
  17. 17. Tornado • Land based storm • Lowest air pressure on record • Average speed of winds ( 100 mph) • Size from a few feet to a mile or more • Occur where warm and cold air meet • Last only a few seconds to a few minutes • Devastating impacts
  18. 18. Fujita-Pearson Scale • Based on 3 second bursts as measured by damage to categories of structures & natural features • Began use in February 2007 • EF 0 – winds 65-85 • 1 86-110 4- 166-200 • 2 111-135 5- 200+ • 3 136-165
  19. 19. Seasonal Tornado activity • 1. Southern tier ( tornado alley) late winter and early spring • 2. Midwest & plains - spring to summer • ( heat/cold & migrating jet stream)3. Tornadoes can happen anywhere at any time ( within the limits of colliding air masses) and have been expanding incidence worldwide in the past decade •
  20. 20. Tornado families
  21. 21. F3 tornado, Moore, Ok. 1999
  22. 22. Topeka, Ka. 1966 – F5 TORNADO DAMAGE
  23. 23. North American air masses
  24. 24. Weather, prediction • Maps NOAA http://www.nws.noaa.gov/outlook_tab.php • Methods: Consistency, seasonality, averages, sensors & modeling
  25. 25. Climate • It’s as easy as abc(de) • Koppen classification • based on suitability for agriculture ( moisture( seasonal) & temperature)- the best proxy for climate is latitude/continentality • A= tropical-& rainy ( over 64degreesF) • B- dry no permanent surface streams
  26. 26. Climate cont. • C. Mild, humid ( summer & winter seasons) –coldest mo under 60 deg, but above 26 degrees, • Summer over 50 degrees • D. Cold snowy forest ( microthermal) • summer above 50, winter below 26 degrees • E. Polar- avg temp in summer below 50 degrees
  27. 27. Climate (3) • H- highland cooler than surrounding flatlands • - 3 letter classifications • 1st letter based on temperature • 2nd letter is season of dryness( or moisture related) • 3rd letter more detailed temperature
  28. 28. Climate influences/ Regions • 1. Latitude – most influence • 2. Continentality – coastal/inland influences • 3. Elevation • 4. temperature ( also influences moisture) • 5. cycles ( seasons) • temperature zones • Precipitation zones ( isohyets)
  29. 29. Koppen map • http://www.uwmc.uwc.edu/geography/100/ koppen_web/koppen_map.htm
  30. 30. Precipitation patterns • Wet equatorial • Trade winds) 25-30 N/S east coast wet, warm ( E. Brazil • Dry west coasts( you are here • Midlatitude deserts & steppes ( inland & rain shadow) Mojave • Moist subtropical ( 25-45 degrees N/S Miami • Midlatitude west coasts ( 35-65 n/s) westerly winds & wet San Francisco
  31. 31. Climate regions- A
  32. 32. Climate region B- Kelso Dunes
  33. 33. Climate C
  34. 34. Climate d- Boreal forest
  35. 35. Climate ET
  36. 36. EF - arctic harp seal
  37. 37. Climate relevance • 1. Physical setting for all plant, animal and human behavior – limits of living things are largely related to temperature - • 2. Relatively unchanging for millions of years – but changes with cycles of Earth’s location and orientation ( orbital and axia • l shifts) • 3 Range of temperatures for humans
  38. 38. Human narrow comfort zone • Homeothermic • Maintains core temperature above average environment temp. • Normal 37 C (98.6) • Lower limit- hypothermia • drop of 1.8 – 3.6F from normal • Heat: hyperthermic Above 38C fever, 40C critical, 44C (100% death rate) or • F: >104F starts, over 106F brain death begins, over 122F certain death
  39. 39. Weather quiz • 1. Diagram a mid-latitude wave cyclone. • - label the parts • - Describe the process of origination • - Which part has warm, clear weather? Why? • - Which part has violent weather? Why?
  40. 40. quiz • 2. How do hurricanes and tornadoes differ? • - Describe the dangers associated with hurricanes. • What areas of the U.S. are at most risk from hurricanes? From Tornadoes? • 3. In the Koppen system – identify the characteristics ( and example of a location) for: Am, BW, ET, Csa climate types
  41. 41. Quiz (3) • 4. How are desert plant and animal species ( and the soil) specially adapted to the lack of moisture? • 5. What danger does a microburst pose to aircraft?

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