1. QUIZ BONUS List Four types of Air Masses (symbols are accepted)
Name the Three Wind Systems “Zones”
BONUS
What are JET STREAMS??

2. Science News

3. GLOBAL WIND SYSTEMS
Result of Earth’s rotation & uneven heating of surface
Transports colder air to the Equator & warmer air to the Poles
Help to equalize the thermal energy on Earth

4. Forces Influencing Wind Speed & Direction
Gravitational Force: equal compression density decrease with altitude
Friction Force: Earth’s rough surface adds to Pressure & Coriolis
Coriolis Force: Earth’s rotation deflecting wind
Pressure Gradient Force: High/Low systems

5. Coriolis Effect Earth’s rotation breaks air masses into smaller cells
Moving air curves to the right in the N. Hemisphere & to the left in the S. Hemisphere

6. PRESSURE SYSTEMS
Low Pressure system air coming up either cloud cover / precipitation or no clouds because no moisture
High pressure system air coming down generally fair skies

7. Pressure Differences

8. Wind & Pressure Relationship
950 mb.
960 mb.
970 mb.
930 mb. H L
WINDS ALWAYS MOVE FROM HIGH PRESSURE AREAS TO LOW PRESSURE AREAS!!!!!!!

9. Makes no sense without caption in book

10. Pressure Centers Cyclones: centers of low pressure, Storm & Clouds
(L) the pressure decreases from the outer isobars toward the center
Anticyclones: centers of high pressure,
Calm & Clear
(H) the pressure increases from the outside toward the center

11. Cyclonic & Anticyclonic Winds
Anticyclones
Winds in a high pressure area move clockwise (S Hemisphere)
Cyclones
Winds in a lower pressure area move counter-clockwise (N Hemisphere)

12. CYCLONE

13. ANTICYCLONE

14. Pressure Centers & Winds
 Weather and Air Pressure
Rising air is associated with cloud formation and precipitation, whereas sinking air produces clear skies.
 Weather Forecasting
Weather reports emphasize the locations and possible paths of cyclones and anticyclones.
Low-pressure centers can produce bad weather in any season.

15. Pressure Systems Collisions
Collision forms a front, boundary that separates air masses of different densities
Air masses retain their identities
Warmer, less dense air forced aloft
Cooler, denser air acts as wedge

16. Warm air replaces cooler air
4 Types of Fronts
Warm front
Warm air replaces cooler air
Clouds become lower as the front nears
Slow rate of advance
Light-to-moderate precipitation

17. Warm front

18. Cold Fronts Cold air replaces warm air
Advances faster than a warm front
Associated weather is more violent than a warm front
Intensity of precipitation is greater
Duration of precipitation is shorter

19. Cold front

20. Stationary front Occluded front
Flow of air on both sides of the front is almost parallel to the line of the front
Surface position of the front does not move
Occluded front
Active cold front overtakes a warm front
Precipitation is associated with warm air being forced up

21. Formation of an Occluded front

22. HOMEWORK
REVIEW TEXT
p. 312 – 324
&
CH 12 Notes