1. Table of Contents
Air Masses and Fronts
Storms
Predicting the Weather

2. Comparing and Contrasting
- Air Masses and Fronts
Comparing and Contrasting
As you read, compare and contrast the four types of fronts by completing a table like the one below.
Types of Weather
Front
How It Forms
Cold front
A cold air mass overtakes a warm air mass.
Clouds, possibly storms with heavy precipitation
Warm front
A warm air mass overtakes a cold air mass.
Clouds, light precipitation
Stationary front
Cold and warm air masses meet, but neither can move the other.
Clouds, precipitation
Occluded front
A warm air mass is caught between two cold air masses.
Clouds, precipitation

3. Types of Air Masses - Air Masses and Fronts
Air masses can be warm or cold, and humid or dry. As an air mass moves into an area, the weather changes.

4. Classifying Air Masses
- Air Masses and Fronts
Classifying Air Masses
Four major types of air masses influence the weather in North America: maritime tropical, continental tropical, maritime polar, and continental polar.

5. Air Masses and Fronts What is an air mass?
Introduction Pg. 596
What is an air mass?
An air mass is a huge body of air that has similar temperature, humidity, and air pressure at any given height.
Types of Air Masses pg
2. Scientists classify air masses according to ____ and ____.
temperature and humidity
3. Polar air masses typically have low air pressure.
False
4. Compare/Contrast Chart.
A. Maritime Tropical
B. Maritime Polar
C. Continental Tropical
D. Continental Polar

6. Air Masses and Fronts
4e. How are maritime tropical and maritime alike, how are they different? They are alike in that they are both humid. They are different because the tropical air mass is warm and the polar air mass is cool. 4.f. How are continental tropical and continental polar air masses alike, and how are they different? They are alike in that they are both dry. They are different because the tropical air mass is warm and the polar air mass is cool.

7. Air Masses and Fronts 7. Drawings: Cold Front Warm Front
How Air Masses Move pg. 599
5. In the continental United States, major wind belts generally push air masses from ____ to ____.
west to east
6. How do jet streams affect air masses?
As the jet streams blow from west to east, air masses are carried along their track.
Types of Fronts pg
7. Drawings:
Cold Front
Warm Front

8. How a Front Forms - Air Masses and Fronts
The boundary where unlike air masses meet is called a front.

9. Types of Fronts - Air Masses and Fronts
Colliding air masses can form four types of fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.

10. Air Masses and Fronts
Types of Fronts: 8. Cold front C- A rapidly moving cold air mass runs into a slowly moving warm air mass 9. Warm front A- A moving warm air mass overtakes a slowly moving cold air mass. 10. Stationary front D- A cold air mass and a warm air mass meet and remain stalled over an area. 11. Occluded front B-A warm air mass is caught between two cooler air masses.

11. Air Masses and Fronts 12. Sentences that are true about fronts:
Cold fronts can bring violent thunderstorms.
Warm fronts are associated with clouds and rain.
Stationary fronts may bring many days of clouds and precipitation.
Cyclones and Anticyclones pg
13. A swirling center of low air pressure is called a(an) ___.
cyclone
14. Winds spiral inward toward the center of a cyclone.
True

12. Air Masses and Fronts
15. What type of weather is associated with cyclones? Storms and precipitation are associated with cyclones. 16. Winds in an anticyclone spin clockwise in the Northern Hemisphere. True 17. What type of weather is generally associated with anticyclones? Dry, clear weather is generally associated with anticyclones.

13. Cyclones and Anticyclones
- Air Masses and Fronts
Cyclones and Anticyclones
Winds spiral inward towards the low-pressure center of a cyclone. Winds spiral outward from the high-pressure center of an anticyclone.

14. Weather Fronts Activity
- Air Masses and Fronts
Weather Fronts Activity
Click the Active Art button to open a browser window and access Active Art about weather fronts.

15. End of Section: Air Masses and Fronts

16. - Storms
Sequencing
As you read, make a flowchart like the one below that shows how a hurricane forms. Write each step of the process in a separate box in the order in which it occurs.
Hurricane Formation
Begins as a low-pressure area over warm water, or a tropical disturbance.
Warm, humid air rises and begins to spiral.
As air rises, more warm, moist air is drawn into the system and the hurricane gains energy.
As winds spiral inward, bands of high winds and heavy rains form.

17. Thunderstorm Formation
- Storms
Thunderstorm Formation
A thunderstorm forms when warm, humid air rises rapidly within a cumulonimbus cloud.

18. Storms
Introduction pg.604
What is a storm?
A storm is a violent disturbance in the atmosphere.
Thunderstorm pg
2. Types of clouds in which thunderstorms form:
Cumulonimbus
3. A sudden energy discharge between parts of a cloud, between nearby clouds, or between a cloud and the ground is called ____.
lightning
4. Sentences that are true about thunder.
You hear it after you see the lightning that caused it.
It occurs because lightning heats the air.

19. Storms
5. A sudden, violent flood that occurs within a few hours, or even minutes, of a storm is called a(n) ____.
flash flood
6. Sentences that is a way to stay safe in a thunderstorm:
Avoid touching electrical appliances
Get out of the water if you are swimming.
Don’t use the telephone.
Tornadoes pg
7. What is a tornado?
A tornado is a rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth’s surface.

20. Storms
8. Tornadoes develop in the same type of clouds that bring thunderstorms.
True
9. Sentences that are true about where and when tornadoes occur.
Tornadoes occur often in the Great Plains.
Tornadoes occur more often in the United States than in any other country.

21. Storms
10. Flowchart: 1. Warm air is forced upward along a a._____ front. a. cold 2. As the air rises, it b. _______. b. cools 3. c.______ falls. c. Heavy rain (sometimes with hail) 11. Where is the safest place to be during a tornado? The safest place to be is in the basement of a well-built building.

22. Tornado Formation - Storms
Tornadoes can form when warm, humid air rises rapidly in thick cumulonimbus clouds—the same type of clouds that bring thunderstorms.

23. - Storms
Tornado Alley
Tornadoes in the U.S. are most likely to occur in a region known as Tornado Alley.

24. Structure of a Hurricane
- Storms
Structure of a Hurricane
In a hurricane, air moves rapidly around a low-pressure area called the eye.

25. Hurricane Andrew - Storms
The path of Hurricane Andrew over three consecutive days can be seen below.

26. Storms 12.Sentences that are true about a hurricane:
Hurricanes pg
12.Sentences that are true about a hurricane:
It is a tropical storm.
It forms over water.
13. The center of a hurricane is called the ____.
eye
14. Hurricanes do not last as long as other storms.
False

27. Storms
15. A “dome” of water that sweeps across the coast where the hurricane lands is called a(n) ____.
storm surge
16. If you hear a hurricane warning and are told to evacuate, you should leave the area immediately.
True
Winter Storms
17. When does snow fall?
Snow falls during a storm when the whole atmosphere is colder than 0 degrees Celsius.

28. Storms 18. Sentences that are true about lake-effect snow:
It occurs because land cools more rapidly than water.
It occurs when humid air rises over a body of water and later cools over land.
19. What should you do if you are caught in a snowstorm?
You should try to find shelter from the wind, cover exposed parts of your body, and stay dry. If you are in a car, the driver should keep the engine running only if the exhaust pipe is clear of snow.

29. Lake-Effect Snow - Storms
As cold dry air moves across the warmer water, it becomes more humid as water vapor evaporates from the lake surface. When the air reaches land and cools, snow falls.

30. More on Thunder and Lightning
- Storms
More on Thunder and Lightning
Click the Planet Diary button for an activity about thunder and lightning.

31. Click the Video button to watch a movie about tornadoes.
- Storms
Tornadoes
Click the Video button to watch a movie about tornadoes.

32. Click the Video button to watch a movie about hurricanes.
- Storms
Hurricanes
Click the Video button to watch a movie about hurricanes.

33. End of Section: Storms

34. Previewing Visuals - Predicting the Weather
Before you read, preview Figure 21, a weather map. Then write four questions that you have about the map in a graphic organizer like the one below. As you read, answer your questions.
Previewing Figure 21
Q. What type of front is located west of Okalahoma City?
A. A cold front
Q. What do the stick symbols indicate?
A. Amount of cloud cover, atmospheric pressure, wind direction and speed, and temperature
Q. What are the slender, curvy lines?
A. Isobars, which join places with the same air pressure
Q. What does the symbol to the east of Florida mean?
A. A hurricane

35. Predicting the Weather
Weather Forecasting pg. 617
Scientists who study the causes of weather and try to predicting it are called ____.
Meteorologist
2. Sources of weather information for meteorologists:
Radar
Instruments carried by balloons
Satellites
Weather Technology pg
3. In what two areas have improvements in technology improved the accuracy of weather forecasts?
The areas are gathering weather data and using computers to make forecasts.

36. Predicting the Weather
4. Weather forecasts for over three days into the future are never reliable. False 5. Flowchart: A. weather station B. Satellites C. Computers D. Meteorologists E. Weather forecast

37. Predicting the Weather
5f. What happens to the calculations in step 3 if the data collected is step 1 changes? The calculations would change to reflect the revised weather data. 5g. How would this change what is prepared in step 5? The forecast prepared by meteorologists would change to reflect the revised calculations produced by the computer.

38. Predicting the Weather
6. Sentences that are true about weather balloons or weather satellites:
Weather balloons can carry instruments as high as the stratosphere.
Weather balloons often carry instruments that measure temperature, air pressure, and humidity.
Weather satellites take pictures of Earth from the exosphere.
7. Sentences that are true about computer weather forecasts:
Computer forecasts are based on weather conditions from many weather stations.
When new weather data come in, new computer forecasts are produced.

39. Reading Weather Maps - Predicting the Weather
This is the type of weather map produced by the National Weather Service. It shows data collected from many weather stations.

40. Reading Weather Maps - Predicting the Weather
Weather maps in newspapers use symbols to show fronts, high- and low-pressure areas, and precipitation. Color bands indicate different temperature ranges.

41. Reading Weather Map Symbols
- Predicting the Weather
Reading Weather Map Symbols
The figure below shows what various weather symbols mean.

42. Predicting the Weather
Reading Weather Maps pg
8. What data are indicated by symbols on a weather map?
The symbols indicate amount of cloud cover, atmospheric pressure, wind direction, wind speed, and temperature for individual weather stations. Weather maps also show the location of air masses and fronts.
9. What are the temperature, air pressure, and wind direction at the weather station represented by the symbol show?
The temperature is 55 degrees Farenheight, the air pressure is 1028 millibars, and the wind is from the south-west at miles per hour.

43. Predicting the Weather
10. Isobars B-Lines on a weather map joining places that have the same air pressure. 11. Isotherms A- Lines on a weather map joining places that have the same temperature 12. What do the standard symbols on newspaper weather maps show? The symbols show fronts, areas of high and low pressure, types of precipitation, and temperature range.

44. Predicting the Weather
13. The “butterfly effect” refers to the fact that a small change in the weather today can mean a larger weather change in the future. True

45. Predicting the Weather
Key Terms:
Storm
Polar
Maritime
Isobars
Occluded
Tropical
Lightning
Isotherms
Tornado
Hurricane
meteorologist

46. Red Sky - Predicting the Weather
A red sky is one kind of observation that helps people to predict the weather.

47. Computer Weather Forecasting
- Predicting the Weather
Computer Weather Forecasting
Scientists use computers to develop different models of how a front may move. These predictions are then used to make weather forecasts. As more data become available, some models are found to be incorrect, while others are found to closely fit the predicted conditions. The upper graph shows the predicted air pressure from two models. The lower graph shows actual data for air pressure.

48. Computer Weather Forecasting
- Predicting the Weather
Computer Weather Forecasting
Reading Graphs:
What two variables are being graphed?
Time of day and air pressure

49. Computer Weather Forecasting
- Predicting the Weather
Computer Weather Forecasting
Interpreting Data:
How is air pressure predicted to change according to each model in the top graph?
According to model A, air pressure will drop slightly then increase. According to model B, air pressure will steadily decrease.

50. Computer Weather Forecasting
- Predicting the Weather
Computer Weather Forecasting
Inferring:
Which computer model most closely matches the actual air pressure data?
Model B

51. Computer Weather Forecasting
- Predicting the Weather
Computer Weather Forecasting
Predicting:
What weather would you forecast for Monday and Tuesday? Explain.
Stormy weather, clouds, and precipitation accompany low air pressure.

52. Click the Planet Diary button for an activity about weather maps.
- Predicting the Weather
More on Weather Maps
Click the Planet Diary button for an activity about weather maps.

53. Click the PHSchool.com button for an activity about Doppler radar.
More on Doppler Radar
Click the PHSchool.com button for an activity about Doppler radar.

54. End of Section: Predicting the Weather

55. Graphic Organizer Typical Time of Year Type of Storm Where Forms
Safety Rules
Within large cumulonimbus clouds
Seek shelter, avoid trees and water.
Thunderstorms
Spring or Summer
Move to a storm shelter or basement if possible; stay away from windows and doors.
Tornado
Cumulonimbus cloud
Spring, early summer
Over warm ocean water
Late summer and into autumn
Evacuate or move inside a well-built building.
Hurricane

56. End of Section: Graphic Organizer