2. Warm up  Answer these questions in your notebook: 1. What is the difference between humidity and relative humidity? 2. What are clouds made of? 3. List the differences between a cold front and a warm front. Sketch the side profile of each.

3. QUIZ!

4. High Pressure Systems  Formed when air moves all the way around a high-pressure center Air sinks down Spreads out toward areas of low pressure

5. Characteristics  Large and change slowly  Moves slowly clockwise  Clear skies and calm air  This is due to air sinking to a lower altitude, which causes it to warm up a little bit (clouds disappear)

6. Low Pressure Systems  Surrounds a center of low pressure  Air moves in toward lowest pressure  Moves upward to higher altitude  Upward motion moves air faster

7. Characteristics  Stormy weather  Form where a warm front meets a cold front  Moves quickly counter-clockwise

8. Low Pressure System Examples  Tropical Storms  Hurricanes  Winter Storms  Severe Storms

9. Thunderstorms  Definition: Storm w/ lightning and thunder  Caused by rising moist air  Warm, humid air moves vertically into cooler air above

10. Thunderstorm Formation: Cumulus Stage 1. Rising humid air (updraft) forms a cumulus cloud.  Energy increases the air motion, forming a cumulonimbus cloud.

11. Mature Stage 2. Large ice particles form in the low temps near the top of the cloud.  They fall and pull cold air down with them, forming a strong downdraft  Downdraft brings heavy rain or hail  This is the most severe stage of a thunderstorm

12. Dissipating Stage 3. Downdraft spreads out, which blocks more warm air from moving upward  The blocking of warm air causes the storm to slow down and eventually end

13. Characteristics  Thunderstorms can form: 1. At a cold front ○ Air can be forced upward quickly 2. Within an air mass ○ Uneven heating produces convection and thunderstorms

15. Effects of Thunderstorms  Flash Floods  Strong winds  Hail  Lightning  Tornadoes

16. Video Segment  http://app.discoveryeducation.com/playe r/?assetGuid=0637b2e7-8063-48bd- ada4- 64740657e954&fromMyDe=0&isPrinterF riendly=0&provider=&isLessonFromHeal th=0&productcode=DETB&isAssigned=f alse&includeHeader=YES&homeworkG uid=