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WEATHER

WEATHER. AND CLIMATE. INTRODUCTION TO GEOGRAPHY. WEATHER & CLIMATE WEEK. Instructor: Matt Letts ( matthew.letts@uleth.ca, UHall C850) Office Hours: Tuesday 13h30 – 15h00. SESSION GOALS: Geography majors Learn about the fundamentals of meteorology to prepare you for

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WEATHER

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  1. WEATHER AND CLIMATE

  2. INTRODUCTION TO GEOGRAPHY WEATHER & CLIMATE WEEK Instructor: Matt Letts (matthew.letts@uleth.ca, UHall C850) Office Hours: Tuesday 13h30 – 15h00 • SESSION GOALS: • Geography majors • Learn about the fundamentals of • meteorology to prepare you for • Weather & Climate 2015 • Non Geography majors • Understand the atmosphere around • you and interpret a surface weather • map

  3. WEATHER & CLIMATE WEEK CONTENTS • Our Energy Source • - The Sun • - Radiation Emission • - What Causes Seasons? • - Earth’s Radiation Balance • 2. Weather vs. Climate • - Weather & Climate Defined (p. 233) • - Why Study Weather? • 3. Atmospheric Circulation • - Air Pressure is Everywhere (p. 271-273) • - Forces Acting to Create Wind (p. 274-281) • - Global Atmospheric Circulation (p. 281-290)

  4. WEATHER & CLIMATE WEEK CONTENTS • The Importance of Water Vapour • - Specific & Relative Humidity • - Vapour Pressure • 5. Instability and Cloud Formation • - Causes of Instability (p. 238) • - Causes of Precipitation (p. 237-243) • 6. Analysis of Surface Weather Maps • - Understanding Weather Symbols (p. 244) • - The Mid-latitude Cyclone (p. 243-256) • Optional Reading: • http://www.physicalgeography.net/fundamentals/chapter7.html

  5. OUR ENERGY SOURCE

  6. Stefan-Boltzmann Law As the temperature of an object increases, more radiation is emitted each second Energy emitted = (T0)4

  7. Wien’s Displacement Law As the temperature of a body increases, so does the proportion of shorter wavelengths

  8. See: http://weather.msfc.nasa.gov/cgi-bin/post-goes

  9. Day and Night (09h00 MDT, Oct 23, 2006) http://www.fourmilab.ch/cgi-bin/uncgi/Earth/action?opt=-p

  10. WHEN ARE WE CLOSEST TO THE SUN?

  11. JANUARY !?!

  12. L K TO SPACE=31 L TO SPACE=69 100-31-69=0 100 Heat transfer 7+24=31 ! Compensates for radiation imbalance at surface ABSORPTION 46+19+4=69 L<K !! 46-15=31 Source: NOAA

  13. SURFACE ALBEDO • White snow 0.80-0.95 • Old snow 0.40-0.60 • Vegetation 0.15-0.30 • Light colour soil 0.25-0.40 • Dark colour soil 0.10 • Clouds 0.50-0.90 • Calm water 0.10 (midday)

  14. WHEN IS THE HOTTEST PART OF THE DAY?

  15. 7.5 cm Air Temperatures at Lakeview Ridge, WLNP 7.5 cm Air Temperature (C) Aug 18 Aug 19 Aug 20 Aug 21 Aug 22, 2005

  16. WEATHER

  17. Current weather conditions Cloudy Temp.: +7°C Pressure: 101.8kPa Visibility: 48km Humidity: 54% DewPoint: -1°C Wind: WNW 26km/h 09h00 October 23, 2006 http://weatheroffice.ec.gc.ca/city/pages/ab-30_metric_e.html

  18. Radiation Sensors (PAR and K) Raingauge Thermometer (thermister) held within a Gill Radiation Shield SENSIBLE HEAT Datalogger

  19. OUR WEATHER IS IN THE TROPOSPHERE

  20. Hurricane Katrina (August 29, 2005)

  21. Lethbridge, Alberta

  22. MAJOR ICE STORM AFFECTS EASTERN CANADA/ NE USA JANUARY 1998 Photo: CBC

  23. CLIMATE

  24. SOUTH CASCADE GLACIER RECEDES WASHINGTON, USA 1979 2000 1928 Photos: National Snow and Ice Data Center

  25. Upsala Glacier, Argentina

  26. Source: IPCC

  27. Weather Climate a) air temperature Long term averages b) atmospheric pressure of weather (eg. 30 y) c) humidity d) clouds Means e) precipitation Extremes f) visibility Variability g) wind

  28. CLIMOGRAPHS LETHBRIDGE, AB VANCOUVER, BC

  29. Atmospheric Circulation

  30. Atmospheric Pressure vs. Altitude Source: Ahrens (1994)

  31. Source: Solomon, 2000

  32. WIND

  33. PRESSURE GRADIENT FORCE Definition: The difference in atmospheric pressure per unit distance PGF acts at right angles to isobars of equal pressure H L 102.2 99.8 101.4 100.6 600 km Pressure Gradient Force = 2.4 kPa / 600 km = 0.4 kPa / 100 km

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