Table of Contents Air Masses and Fronts Storms Predicting the Weather
- 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
- Air Masses and Fronts Types of Air Masses Air masses can be warm or cold, and humid or dry. As an air mass moves into an area, the weather changes.
- 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.
Air Masses and Fronts 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. 597-598 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
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.
Air Masses and Fronts 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. 600-601 7. Drawings: • Cold Front • Warm Front
- Air Masses and Fronts How a Front Forms The boundary where unlike air masses meet is called a front.
- Air Masses and Fronts Types of Fronts Colliding air masses can form four types of fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.
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.
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.602-603 13. A swirling center of low air pressure is called a(an) ___. cyclone 14. Winds spiral inward toward the center of a cyclone. True
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.
- 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.
- Air Masses and Fronts Weather Fronts Activity Click the Active Art button to open a browser window and access Active Art about weather fronts.
- 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 windsand heavy rains form.
- Storms Thunderstorm Formation A thunderstorm forms when warm, humid air rises rapidly within a cumulonimbus cloud.
Storms Introduction pg.604 • What is a storm? A storm is a violent disturbance in the atmosphere. Thunderstorm pg. 605-606 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.
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.606-608 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.
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.
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.
- Storms Tornado Formation Tornadoes can form when warm, humid air rises rapidly in thick cumulonimbus clouds—the same type of clouds that bring thunderstorms.
- Storms Tornado Alley Tornadoes in the U.S. are most likely to occur in a region known as Tornado Alley.
- Storms Structure of a Hurricane In a hurricane, air moves rapidly around a low-pressure area called the eye.
- Storms Hurricane Andrew The path of Hurricane Andrew over three consecutive days can be seen below.
Storms Hurricanes pg.610-611 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
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.
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.
- Storms Lake-Effect Snow 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.
- Storms More on Thunder and Lightning Click the Planet Diary button for an activity aboutthunder and lightning.
- Storms Tornadoes Click the Video button to watch a movie about tornadoes.
- Storms Hurricanes Click the Video button to watch a movie about hurricanes.
- Predicting the Weather Previewing Visuals 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
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. 618-619 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.
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
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.
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.
- Predicting the Weather Reading Weather Maps This is the type of weather map produced by the National Weather Service. It shows data collected from many weather stations.
- Predicting the Weather Reading Weather Maps Weather maps in newspapers use symbols to show fronts, high- and low-pressure areas, and precipitation. Color bands indicate different temperature ranges.
- Predicting the Weather Reading Weather Map Symbols The figure below shows what various weather symbols mean.
Predicting the Weather Reading Weather Maps pg. 620-622 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 21-25 miles per hour.
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.
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
Predicting the Weather Key Terms: • Storm • Polar • Maritime • Isobars • Occluded • Tropical • Lightning • Isotherms • Tornado • Hurricane • meteorologist
- Predicting the Weather Red Sky A red sky is one kind of observation that helps people to predict the weather.
- 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.
Time of day and air pressure Reading Graphs: What two variables are being graphed? - Predicting the Weather Computer Weather Forecasting
According to model A, air pressure will drop slightly then increase. According to model B, air pressure will steadily decrease. Interpreting Data: How is air pressure predicted to change according to each model in the top graph? - Predicting the Weather Computer Weather Forecasting
Model B Inferring: Which computer model most closely matches the actual air pressure data? - Predicting the Weather Computer Weather Forecasting