Notes: Air Masses and Predicting the Weather Fronts Air Masses move across the land or oceans; they meet but do not mix Six major air masses affect the weather across the U.S. 3. In North America, most air masses move from west to east. The jet stream is a band of high-speed wind about 10 kilometers above the surface of Earth that pushes air masses along. 4. A front is where air masses meet and collide. A boundary forms between the two air masses. Sudden changes in weather conditions can occur as a front passes. 5. There are four types of fronts: cA Continental Arctic (very cold, very dry) mP Maritime Polar (cool, moist) mP Maritime Polar (cool, moist) cP Continental Polar (cool, dry) mT Maritime Tropical (warm, moist) mT Maritime Tropical (warm, moist) cT Continental Tropical (hot, dry) mT Maritime Tropical (warm, moist)

Cold Front – When a cold air mass meets a warm air mass and the cold air edges its way under the warm air Can advance rapidly Thunderstorms often form b. Warm Front- 1. A moving warm air mass collides with a slow cold air mass 2. warm air moves over the cold air 3. moves slowly; bad weather can last for days 4. when it moves it leaves behind warm, humid air

c. Stationary front- 1. cold and warm air meet but neither are strong enough to move the other 2. condenses when they meet and form rain, snow, fog or clouds 3. if it stalls it brings several days of clouds and precipitation d. Occluded Front- 1. warm air mass is caught between two colder air masses 2. cold air mass pushes warm air up 3. warm air is occluded (cut off) from the ground 4. brings rainy, cloudy, or snowy weather

L H High and Low Pressure Systems 1. High Pressure System – the air sinks, winds blow outward from the center, turning clockwise; brings clear skies, dry weather, gentle winds 2. Low Pressure System – the air rises, winds spiral in towards the center in a counterclockwise direction; brings cloudy, wet weather, with strong, gusty winds Predicting the weather 1. Meteorologists are scientist who study and try to predict the weather. 2. They use maps, charts, computers, and other technology to analyze weather data and to prepare weather forecasts. 3. Meteorologists get their information form the National Weather Service, which uses weather balloons, satellites, radar, and surface instruments to gather data. 4. Computers help process all of this weather data quickly to help forecasters make predictions. Forecasts are fairly accurate up to five days in the future. 5. Some weather maps show curved lines that connect places where certain conditions are the same. a. Isobars – lines joining places on the map that have the same air pressure. b. Isotherm– lines joining places that have the same temperature H L

Notes: Air Masses and Predicting the Weather Fronts _______________move across the land or oceans; they meet but do not mix ___________________________affect the weather across the U.S. 3. In North America, most air masses move from west to east. The _________________is a band of high-speed wind about 10 kilometers above the surface of Earth that pushes air masses along. 4. A ___________is where air masses meet and collide. A boundary forms between the two air masses. Sudden changes in weather conditions can occur as a front passes. 5. There are four types of fronts:

___________________– When a cold air mass meets a warm air mass and the cold air edges its way under the warm air Can ___________________ _______________often form b. ___________________- 1. A moving warm air mass collides with a slow cold air mass 2. warm air moves over the cold air 3. moves __________________; bad weather can _____________________ 4. when it moves it leaves behind warm, humid air

c. __________________________- 1 c. __________________________- 1. cold and warm air meet but _______________________________ ____________________________________ 2. condenses when they meet and form rain, snow, fog or clouds 3. if it stalls it brings several days of clouds and precipitation d. _____________________- 1. ________________________________________________________ 2. cold air mass pushes warm air up 3. warm air is occluded (___________________) from the ground 4. brings rainy, cloudy, or snowy weather

High and Low Pressure Systems 1. ______ Pressure System – the air sinks, winds blow outward from the center, turning clockwise; brings clear skies, dry weather, gentle winds 2. ______ Pressure System – the air rises, winds spiral in towards the center in a counterclockwise direction; brings cloudy, wet weather, with strong, gusty winds Predicting the Weather 1. ____________________are scientist who study and try to predict the weather. 2. They use maps, charts, computers, and other technology to analyze weather data and to prepare weather forecasts. 3. Meteorologists get their information form the __________________________, which uses weather balloons, satellites, radar, and surface instruments to gather data. 4. Computers help process all of this weather data quickly to help forecasters make predictions. Forecasts are fairly accurate up to _____days in the future. 5. Some weather maps show curved lines that connect places where certain conditions are the same. a. ______________– lines joining places on the map that have the same air pressure. b. ________________– lines joining places that have the same temperature