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. *

5. 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 around the object
(High or low?) *

6. Barometer: device used for measuring air pressure
Unit:
millibars (mb)
inches of mercury
Torricelli: invented the mercury barometer in 1643 *

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

8. 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 *

9. Closely spaced isobars: indicate a steep pressure gradient and high winds.
Widely spaced isobars: indicate a weak pressure gradient and light winds. *

10. Winds blow counterclockwise Winds blow outward and clockwise
Low Pressure Centers
High Pressure Centers
AKA
Cyclones
Anti-cyclones
Pressure Behavior
Pressure drops
Pressure increase
Wind Behavior
Winds blow counterclockwise
Winds blow outward and clockwise
Weather Associated
Severe and stormy
Fair and Sunny
Symbol
“L” that is RED
“H” that is BLUE *

12. Wind is a result of horizontal differences in air pressure
Air flows from areas of high pressure to areas of lower pressure. *

14. Jet streams are fast-moving rivers of air
Speed: 120 and 240 kilometers per hour
Direction: West-to-east direction. *

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

16. Anemometer
Measures how fast wind is blowing *

17. Air Masses & Fronts
Air Masses & Fronts 2/22

18. Chapter 20 Air Masses

19. 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.

20. 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

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

22. Classifying Air Masses
NAME
P – Polar
LOCATION
High Latitudes towards the poles
TEMPERATURE
Cold Temps
T – Tropical
Low Latitudes towards the equator
Warm Temps
C – Continental
Over land mass
Cold or warm, depending on the latitude
M – Maritime
Over water

23. Four Basic Types of Air Masses
cP – Continental Polar
dry and cool
cold and dry in winter and summer
cT – Continental Tropical
dry and warm
hot, drought-like conditions
mT – Maritime Tropical
wet and warm
source of precipitation in the United States
mP – Maritime Polar
wet and cold
mild, humid, unstable cold air from Canada

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

26. Probing Questions Probe to get to that air masses move (wind) and the space between two air masses is the front.

27. Fronts When two air masses meet
boundary separating the two air masses.

28. 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

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

30. 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

31. Winds blow counterclockwise Winds blow outward and clockwise
Low Pressure Centers
High Pressure Centers
Centers of
Low Pressure
High Pressure
AKA
Cyclones
Anti-cyclones
Pressure Behavior
Pressure drops
Pressure increase
Wind Behavior
Winds blow counterclockwise
Winds blow outward and clockwise
Weather Associated
Severe and stormy
Fair and Sunny
Symbol
“L” that is RED
“H” that is BLUE *

33. ​Tornadoes & Thunderstorms

34. -Thunderstorms -Tornadoes -Hurricanes
Severe Storms
-Thunderstorms -Tornadoes -Hurricanes

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

36. 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

37. Occurrence and Development
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

38. 3 Stages Cumulus: build up of clouds and moisture
Mature: Heavy rainfall, most active time
Dissipating: light rain, storm is calming down

40. 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 producing rain and hail
Move counterclockwise

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

42. Incredible and Speechless Damage
Fujita Tornado Scale
Category
Winds (MPH)
Winds (KPH)
Damage F0
<73
<116
Light damage F1
73-112
Moderate Damage F2
Considerable Damage F3
Severe Damage F4
Devastating Damage F5
>260
>419
Incredible and Speechless Damage

44. 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

45. Hurricanes 2/24/2017
HURRICANES

46. Indian Ocean – Cyclones Most powerful storm on Earth
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

47. Occurrence and Development of Hurricanes
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

48. Eye: Center of storm, warmest part, winds cease, rain ceases
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
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49. Categorized on the Saffir- Simpson Scale (based on wind speed)
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)

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

51. Weather Symbols