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# Bell Ringer 2/21 /17

Bell Ringer 2/21 /17. Create a circle map on what you know about WEATHER. Unit 3 Air Masses and Severe Weather. Air Pressure &amp; Wind. Air Pressure &amp; Wind 2/21/2017. Air pressure - the pressure exerted by the weight of air above Exerted in all directions (up, down, and sideways)

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## Bell Ringer 2/21 /17

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1. Bell Ringer 2/21/17 • Create a circle map on what you know about WEATHER

2. Unit 3 Air Masses and Severe Weather

3. Air Pressure & Wind • Air Pressure & Wind 2/21/2017

4. Air pressure - the pressure exerted by the weight of air above • Exerted in all directions (up, down, and sideways) • Air pressure doesn’t just push down on an object, it pushes all aroundthe object (High or low?)

5. Barometer: device used for measuring air pressure • Unit: • millibars (mb) • inches of mercury • Torricelli: invented the mercury barometer in 1643 • https://www.youtube.com/watch?v=GRxglLS1YWI

6. The unequal heating of earth’s surface generates pressure differences • Solar radiation is the ultimate energy source for wind

7. Isobars • lines on a map that connect places of equal air pressure • A pressure gradient • The spacing of isobars shows the amount of pressure change over a given time

8. Closely spaced isobars: indicatea steep pressure gradient and high winds. • Widely spaced isobars: indicate a weak pressure gradient and light winds.

9. Wind is a result of horizontaldifferences in air pressure • Air flows from areas of high pressure to areas of lowerpressure.

11. Jet streams are fast-moving rivers of air • Speed: 120 and 240 kilometers per hour • Direction: West-to-east direction. • https://www.youtube.com/watch?v=WAve9PlK4Gg • https://www.youtube.com/watch?v=CgMWwx7Cll4 https://www.youtube.com/watch?v=huweohIh_Bw

12. Direction • Labeled by the direction from which they blow • Ex: winds blowing from the Southeast. • Tool: Wind Vane

13. Anemometer • Measures how fast wind is blowing

14. Air Masses & Fronts • Air Masses & Fronts 2/22

15. Chapter 20 Air Masses

16. Probing Questions • Refer back to heating of land and water activity • Now lets look at heating of land and water on a global scale! (continental and maritime) • Go back to solar radiation. Warmer at the equator. (Tropical and Polar) at equator and poles.

17. Air Mass • An air mass is a big body of air that is characterized by similar temps and moisture • When an air mass moves out of the area it formed over, it keeps the same temp and moisture conditions • As it moves, the characteristics of an air mass change and so does the weather in the area it moves over

18. Classifying Air Masses • Air masses are classified by temperature and surface area over which they form

19. Classifying Air Masses

20. Four Basic Types of Air Masses

21. Weather in North America is influenced by continental polar and maritime tropical air masses

22. Probing QuestionsProbe to get to that air masses move (wind) and the space between two air masses is the front.

23. Fronts • When two air masses meet • boundary separating the two air masses.

24. Warm Front • A warm front – warm air moves into an area formerly covered by cooler air • Warm air glides up over a cold, dense air mass • Weather Conditions: Light to moderate rain

25. Cold Front Cold air mass moves into an area occupied by warmer air. Weather Conditions: Thunderstorms

26. Stationary and Occluded Fronts • stationary front: The surface position of the front does not move (steady rain for days) • occluded front: when an active cold front overtakes a warm front

28. Severe Storms -Thunderstorms -Tornadoes -Hurricanes

29. Thunderstorms -Is a storm that generates thunder and lightning -Frequently produces gusty winds, heavy rain, and hail Associated with cumulonimbus clouds

30. Lightning: results from the build up and discharge of electric energy between positively (ground) and negatively (clouds) charged area -Thunder: the sound of rapidly expanding gases usually associated with lightning https://www.youtube.com/watch?v=G7GbOFlFODE https://www.youtube.com/watch?v=jM8h60S1GsM

31. Occurrence and Development • Occurrence • At any given time, there are an estimated 2000 thunderstorms in progress on Earth • Mostly in the tropics • Development • Thunderstorms form when warm, humid air rises in an unstable environment • 3 Stages

32. 3 Stages • Cumulus: build up of clouds and moisture • Mature: Heavy rainfall, most active time • Dissipating: light rain, storm is calming down

33. Tornadoes • Tornadoes - violent low pressure windstorms that take the form of a rotating column of air (vortex). • The vortex extends downward from a cumulonimbus cloud producingrain and hail • Move counterclockwise https://www.youtube.com/watch?v=oQPBjQHG8gc https://www.youtube.com/watch?v=V-Xbj0aEkRQ

34. Occurrence, Development, and Intensity of Tornadoes • Occurrence • 770 occur each year • Tornado Season • April to June • Associated with severe thunderstorms • Intensity • Fujita Tornado scale • Based on the amount of damage

36. Tornado Warnings vs. Watches • Watches : Possibility of a tornado to be developed in the area • Warning: Tornado has been seen by people or indicated by radar

37. Hurricanes 2/24/2017 • HURRICANES

38. Hurricanes • Whirling tropical cyclones (low pressure system) producing winds of at least 119 km per hour (73 mph) • US – Hurricanes • Pacific – Typhoons • Indian Ocean – Cyclones • Most powerful storm on Earth

39. Occurrence and Development of Hurricanes Occurrence • Form between 5 and 20 degrees north and south latitude • Season: June 1 to November 30th Development of Hurricanes • Hurricane develop most often in the late summer when water temperatures are warm enough to provide the necessary heat and moisture to the air • Low Pressure: Spins counterclockwise

40. Parts of a Hurricane Eye: Center of storm, warmest part, winds cease, rain ceases Eye wall: Strongest winds and rain Spiral Rain Bands: extend out from the eye wall https://www.youtube.com/watch?v=Wk_FVXVnE2I

41. Hurricane Intensity • Storm Surge: is a dome of water that sweep across the coast caused by the hurricane’s winds • Categorized on the Saffir-Simpson Scale (based on wind speed)

42. Hurricane Warning and Watches • Hurricane Watch: could see hurricane related hazards within 48 hours • Hurricane Warning: Could see hurricane winds within 36 hours

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