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Chapter 18-19

Chapter 18-19. Meteorology. Lesson 4. The Causes of Weather. Think About It…. Where does the weather in our country come from?. Focus Question…. Which air masses determine the weather in our country?. Weather or Climate?. Weather or Climate? The current state of the atmosphere Weather

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Chapter 18-19

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  1. Chapter 18-19 Meteorology

  2. Lesson 4 The Causes of Weather

  3. Think About It… Where does the weather in our country come from?

  4. Focus Question… Which air masses determine the weather in our country?

  5. Weather or Climate? • Weather or Climate? • The current state of the atmosphere Weather • Short term variation in atmospheric conditions Weather • It’s cloudy with a chance of meatballs! Weather

  6. Weather or Climate? • Weather or Climate? • The long term variation in weather Climate • Average weather for a specific location Climate • Winston-Salem is humid, subtropical with 4 seasons. Climate

  7. Energy in the Atmosphere… • What two things are always in motion to distribute heat energy on and around the Earth? • ocean currents • global wind systems • What explains why the poles are never very warm? • The Sun’s rays don’t hit Earth as directly at the poles as at the tropics. (So the same amount of solar radiation is spread over a larger area.)

  8. How the Sun’s Rays Hit Earth… Note how the solar radiation hitting the poles is spread out over a greater area. http://blog.richmond.edu/geog250/files/2010/04/earth-lighting-summer-solstice_en.png

  9. Air Masses… • Continental Tropical • Abbreviation - cT • Origin - land • Origin - tropical • Moisture Content - dry • Temperature - warm http://earth.usc.edu/~stott/Catalina/WeatherPatterns.html

  10. Air Masses… • Maritime Tropical • Abbreviation - mT • Origin – ocean/water • Origin - tropical • Moisture Content - humid • Temperature - warm

  11. Air Masses… Continental Polar • Abbreviation - cP • Origin - land • Origin – high latitudes • Moisture Content - dry • Temperature – cool or cold

  12. Air Masses… • Maritime Polar • Abbreviation - mP • Origin – ocean/water • Origin – high latitudes • Moisture Content - humid • Temperature – cool or cold

  13. Air Masses… • Arctic (Continental) • Abbreviation - cA • Origin – land • Origin - Arctic • Moisture Content – dry • Temperature – very cold

  14. Air Masses That Affect Our Weather…

  15. Tornado Alley… (Accuweather, 6/8/13)

  16. Global Wind Systems http://pulse.pharmacy.arizona.edu/9th_grade/from_global/earth_science/images/wind_patterns.gif http://www.topnews.in/files/atmosphere_wind_patterns.jpg

  17. 2. Chart:Global Wind Systems… • Polar Easterlies • Comes from the east • Located between 60 degrees latitude and the pole in both hemispheres • (60° - 90°)

  18. Global Wind Systems… • Prevailing Westerlies • Comes from the west • Located between 30 and 60 degrees latitude in both hemispheres • (30° - 60°) • This is the wind system that directs fronts across our country.

  19. Global Wind Systems… • Trade Winds • Comes from the east • Located between the equator and 30 degrees latitude in both hemispheres • (0° - 30°)

  20. The Intertropical Convergence Zone • What is the intertropical convergence zone (ITCZ)? • The area near the equator where the trade winds converge. • Air is forced up and creates an area of low pressure. (Remember – warm air rising!) • The ITCZ provides the moisture for many of the world’s tropical rain forests. • Picture on next slide…

  21. The Intertropical Convergence Zone http://library.thinkquest.org/5818/images/mvmt1.gif

  22. The Doldrums… 3. (cont.) What are the doldrums? • Another name for the ITCZ! • Sailing ships would often get stranded in this area because of the light (or no!) winds. • The phrase, “I’m stuck in the doldrums,” came from this phenomenon. Looking for wind!

  23. Horse Latitudes… 4. Why were the horse latitudes so named? • Around the 30 degrees latitude, sinking air creates a belt of high pressure which causes weak winds. • Sailors stranded here were said to throw their horses overboard when they couldn’t feed them!

  24. Weather Systems in the USA 5. Which global wind system is responsible for much of the movement of weather across the USA and Canada? • The prevailing westerlies

  25. Lesson 5 The Causes of Weather

  26. Think About It… What is a “front” the front of?!

  27. Focus Question… What causes the four types of fronts and what weather does each bring?

  28. Terminology • Front… narrow boundary b/tw 2 air masses of different densities (the FRONT of a moving air mass!) • Density differences are caused by… differences in temperatures • High pressure system… cold or cooler air sinking (no/few clouds) • Low pressure system… warm air rising (usually produces clouds)

  29. Pressure Systems – High Pressure • Cold air sinking • Fair weather • Rotates clockwise • Represented as a blue ‘H’ Good ‘H’air Day! http://www.windows2universe.org/earth/Atmosphere/high_pressure.html

  30. Pressure Systems – Low Pressure • Warm air rising • Clouds and precipitation • Rotates counter-clockwise • Represented as a red ‘L’ ‘L’ousy Weather Day! http://www.windows2universe.org/earth/Atmosphere/high_pressure.html

  31. http://3.bp.blogspot.com/_275ZCyVPoFk/TNAxxCklePI/AAAAAAAAAJs/VFM3DzpqDzg/s1600/meteo.jpghttp://3.bp.blogspot.com/_275ZCyVPoFk/TNAxxCklePI/AAAAAAAAAJs/VFM3DzpqDzg/s1600/meteo.jpg Cold Front… http://www.cdli.ca/courses/sci2200/unit02_org01_ilo03/b_activity.html • Definition – Cold, dense air displaces warm air and forces it up a steep front • Symbol – blue icicles! • Weather – clouds, showers, and thunder storms

  32. Mares’ tails

  33. Mackerel Scales…

  34. Cold Front – A Larger View

  35. http://earth.usc.edu/~stott/Catalina/WeatherPatterns.html Warm Front… http://www.cdli.ca/courses/sci2200/unit02_org01_ilo03/b_activity.html • Definition – Advancing warm air displaces cold air and moves up slowly • Symbol – red lava rocks! • Weather – extensive cloudiness and precipitation

  36. Warm Front – A Larger View

  37. Stationary (Stalled) Front… • Definition – Two air masses meet and neither advances • Symbol – blue icicles alternate with red lava rocks • Weather – some clouds and precipitation http://www.kidsgeo.com/geography-for-kids/0129-stationary-fronts.php

  38. StationaryFront – A Larger View

  39. http://www.nvwx.com/wximages/occluded_front.png Occluded Front… • Definition – A cold air mass moves so rapidly that it overtakes a warm front and wedges the warm air up. • Symbol – purple alternating rocks/icicles • Weather – precipitation on both sides of the front http://www.aggiecat.com/Logs/logs-0016-Jan-08/occluded_front_sm.jpg

  40. Occluded Front – A Larger View

  41. Lesson 6 Gathering Weather Data

  42. Think About It… We get our weather from radio/TV/computers. Where do weather-persons get their weather?

  43. Focus Question… How do meteorologists gather data about the weather?

  44. Thermometer • Measures temperature • Degrees Celsius or Fahrenheit • Thermometers contain liquids that expand when heated.

  45. Barometer • Measures air pressure • Millibarsor inches of mercury • A barometer may contain mercury or a vacuum inside a metal chamber that contracts or expands with changes in air pressure. http://robertwhite.com/marineimages/precision_barometer.jpg

  46. Make Your Own Barometer! http://www.home-weather-stations-guide.com/images/simple_barometer.gif

  47. Anemometer • Measures wind speed • … mph or km/h or knots • Has cupped arms that rotate as the wind blows. http://www.smg.gov.mo/www/dm/equip/ws.jpg

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