1. Warm Up Copy Diagram, questions, and write answer
When you hear “severe storms” what do you think of?
On average, how much of the sun’s radiation is reflected back into space?
On average, how much of the sun’s radiation is absorbed by the atmosphere and clouds?

2. Weather Patterns and Severe Storms
2.5.2b Explain how interactions of air masses form frontal boundaries, clouds, and affect wind patterns a Explain factors that affect air density and understand their influence on winds, air masses, fronts and storm systems.

3. Before we begin… Watch as we draw the isotherms on the map.
Remember, ISO means the “same”

4. Objectives
Today I will be able to:
Describe the factors that characterize air masses
Analyze the development of fronts when air masses meet
Relate severe weather to the interaction of air masses

5. Key Points
Air masses are characterized by their temperature and moisture
Air masses take on the characteristics of the land/water they pass over
When air masses meet a front is formed and warm air is always forced upward
Warm fronts bring longer lasting, gentle precipitation
Cold fronts bring heavy, but short lived precipitation

6. Air Masses and Weather
Weather patterns result from the movement of large bodies of air called air masses
Air masses are characterized by similar temperatures and amounts of moisture at certain altitudes.
When air masses move, the characteristics of the air mass change and the weather in the areas over which they move changes

7. Starts off at -460C
Ends up at 700C

8. Air Masses and Weather Example of air mass/weather interaction:
A cold, dry air mass moves over warm, tropical waters
The air mass becomes warmer and wetter
The weather over those waters becomes colder and drier
You try…
A warm, dry air mass moves over a cold, wet area
The air mass becomes ______________ and _______
The weather over that area becomes ____________ and ____________

9. When air masses meet… Fronts
When two air masses meet, they form a front- the boundary that separates the two
There are 4 types of fronts
Warm fronts
Cold fronts
Stationary fronts
Occluded fronts

10. Fronts
Warm fronts
Form when warm air moves into an area formerly covered by cold air
Shown on a weather map by a red line with semi-circles pointing toward the colder air
Warmer air
Colder air

11. Fronts
Warm front

12. Fronts Warm fronts As the warmer, less dense air rises, it cools
This produces clouds and frequent precipitation
Warm fronts move slowly, so the precipitation is light-to-moderate over a large area for a long period of time

13. Fronts
Cold fronts
Form when cold, dense air moves into an area formerly occupied by warmer air
Shown on a weather map by a blue line with triangles pointing toward the warmer air
Colder air
Warmer air

14. Fronts
Cold Front

15. Cold Fronts Fronts Move much more quickly than warm fronts
Associated with heavy precipitation that is short-lived

16. Stationary Fronts Fronts
Form when the flow of air is neither toward the cold air mass, nor toward the warm air mass
The front does not move
Shown by blue triangles on one side and red semicircles on the other
Gentle to moderate precipitation

17. Occluded Front Fronts Forms when a cold front overtakes a warm front
Complex weather patterns

18. Finish worksheet, then answer questions
A cold, dry air mass that moves over warm, tropical waters will likely become ____and _______.
Along which type of front is the intensity of precipitation generally heavy, but short-lived?
Along a front, which type of air is always forced upwards?

19. Thunderstorms Severe Storms
Develop when warm, humid air rises in an unstable environment
Warm air Heavy rain Cooler air

20. Tornadoes Severe Storms Violent windstorms
Form as a vortex extends down from a cumulonimbus cloud
A vortex is a rotating column of air
Most tornadoes form along with severe thunderstorms

21. Tornadoes Severe Storms
Tornado Watches: there is the possibility of a tornado in the area
Tornado Warning: a tornado has been spotted in the area or is indicated by radar

22. Damage Caused by Tornadoes
Extremely high winds can tear buildings apart, slip cars, and even suck the water out of a riverbed

23. Severe Storms Hurricanes
A hurricane is a large, rotating tropical weather system with wind speeds of at least 74 mph
Hurricanes are the most powerful storms on Earth
In other countries they are also known as typhoons and cyclones

24. How Do Hurricanes Form?
A hurricane begins as a group of thunderstorms moving over tropical ocean waters
Winds traveling in two different directions collide causing the storm to spin
Warm water gives the storm energy and causes it to grow

25. Structure of a Hurricane
The eye is a zone of scattered clouds and calm averaging about 20 kilometers in diameter at the center of a hurricane. The eye has the warmest temperatures.
The eye wall is a doughnut-shaped area of intense cumulonimbus development and very strong winds that surrounds the eye of a hurricane.

26. Damage Caused by Hurricanes
Hurricane winds can knock down trees and telephone poles
However, the most damage during a hurricane comes from flooding due to heavy rain and storm surges
A storm surge is a wall of water that builds up over the ocean and can be up to 20 feet before it crashes onto the shore

27. WARM UP 5/11/10
The boundary that separates different air masses is called _____
What is the most abundant gas in the atmosphere?
What is the most important gas for understanding atmospheric processes?
Air that has reached its water vapor capacity is ____________.
What type of winds are produced by steep pressure gradients?

28. FRONT ACTIVITY You will be completing this activity in groups
For each of the pressure systems and fronts:
Draw the symbol
Explain the effect these have on weather

29. YOU BE THE METEOROLOGIST
TODAY-Lots of clouds, a stiff northeast wind, and periods of rain will make for a chilly and wet day. Highs will struggle to reach the upper 50s here in the Triangle, but low 60s are very possible south and east of Raleigh.
SATURDAY-Happy Halloween! No spooky weather is expected at this time. Expect mostly sunny to partly cloudy skies and slightly milder temperatures with highs in the mid to upper 60s. The evening looks nice for trick or treaters, and remember that later tonight we "fall back" to standard time.

30. YOU BE THE METEOROLOGIST
Pretend that you are a meteorologist for Apex, NC. Write a script for you to read during the news describing the fronts and weather patterns Apex has experienced over the past 7 days. Your script should be at least 7 sentences long and be accurate.
EXAMPLE:
On Sunday, Apex experienced a High pressure system causing the weather to be clear and sunny, with highs in the upper 80’s.
Note: exact temperatures may be made up.

31. Raging Planet - Hurricanes as you watch, write at least 5 pieces of info for each of the following categories. Your paper should look like this
HOW HURRICANES FORM 1. 2. 3. 4. 5.
TOOLS AND TECHNIQUES FOR PREDICTING HURRICANES 1. 2. 3. 4. 5.

32. EXIT TICKET
What type of front is drawn as a line with semi-circles extending out?
True or false?- In a cold front the symbols on the front line point toward the cold air.
What type of front is associated with heavy, short-lived precipitation?
High pressure systems are associated with what weather conditions?