Name __________________________ Date _____________ Chapter 3 Notes: Air Masses and Fronts **What causes wind? All winds are caused due to __differences__ in air pressure. Winds blow from high to low: H L 1. ___Weather____ describes the conditions of the atmosphere at a given location for a short period of time. 2. ____Climate____ is the characteristic weather that prevails from season to season and year to year. 3. The _unequal___ _____heating___ of Earth’s surface is the cause of weather. 4. Air masses form when air remains ___stationary (stagnant, still)__ over a large section of Earth’s surface and takes on the conditions of ____temperature____ and ___moisture (humidity)______ from that location. 5. Weather conditions at a location are determined primarily by the ___temperature___, ____moisture____, and ___pressure____ of air masses over that location. 6. Most local weather condition changes are caused by movement of _air_ _masses_. **7. _FRONTS____ are boundaries between air masses. ___Precipitation____ is likely to occur at these boundaries. **8. High-pressure systems (highs, H) generally bring __CLEAR____ weather. Lowpressure systems (lows, L) usually bring _cloudy__, ____wet (stormy)___ conditions. **9. The general movement of highs and lows in the United States is from _WEST_ to _EAST_. **10. Air mass – huge body of air with similar __temperature__, ___moisture (humidity)___, and _______pressure__. 11. Air masses are classified based on their __temperature__ and _moisture/ humidity_ a. Tropical - _Warm_, forms over a __warm (near equator)___ area; b. Polar - ___Cold___, forms over a __cold (near a pole)_ area; c. Maritime - __Wet_, forms over an ___ ocean______; d. Continental - _Dry__, forms over a __continent (land)_____. 12. Four main types of air masses affect the United States a. Maritime Tropical (mT) – form over _warm_ ___ocean__, are __warm__ and ___moist/wet/humid_____. b. Maritime Polar (mP) – form over ___cold___ ____ocean_, are ___cold___ and ___ moist/wet/humid ___. c. Continental Tropical (cT) – form over _warm____ ___land___, are ____warm____ and ____dry_______. d. Continental Polar (cP) – form over ___cold__ ___land__, are ____cold____ and ___dry______. 13. What moves air masses across the U.S.? __jet stream___ ___ (prevailing winds) _ **14. When two different air masses meet you get a __front__, and often storms. 15. Recall: __cold__ air is dense and sinks; __warm____ air is less dense and rises. 16. There are four types of fronts: cold front, warm front, stationary front, occluded front a. Cold Front – forms when _cold__ air catches up to ___warm__ air forcing the warm air upward. (Cold front = the front of a cold air mass) This causes ___clouds, thunderstorms__ and brings ___cold__ air into the area; cold fronts move __quickly_____. b. Warm Front – forms when _warm_ air catches up to ___cold___ air, and the warm air slowly __rises_. (Warm front = the front of a warm air mass) This causes a few days of __clouds and rain_____ and brings ___warm__ air into the area; warm fronts move ___slowly_______. c. Stationary Front – forms when __cold__ and ____warm_ air meet, but neither pushes the other, so the front stalls. (stays still) This causes many days of ___clouds and rain______, until one air mass starts moving again. d. Occluded Front – forms when a cold front catches up to a warm front (and tries to pass!), causing __warm___ air to get caught between two __cold___ air masses. Warm air in the center rises, this causes __severe thunderstorms___. High and Low Pressure Systems **Winds blow from high to low* 17. Cyclones – Low pressure systems – Lows – L Winds blow counterclockwise, inward, and then upward Brings clouds, rain, storms 18. Anticyclones – High pressure systems – Highs – H Winds blow clockwise, downward, and outward Brings clear skies, NO precipitation, (could be warm or cold) 19. Which city, A or B, is more likely to be receiving precipitation? Explain. City A is probably experiencing precipitation since City A is near a (stationary) front. City B is probably NOT experiencing precipitation since City B is near a High pressure center / is NOT near a front Severe Weather Safety 1. Safety in severe weather *What is a storm? A __temporary___ disturbance in the atmosphere. a. Thunderstorms – thunder, lightning, heavy rain, wind Safety – get in a car or a sturdy building; AVOID trees!!! AVOID being the tallest object in an area, AVOID being near the tallest object in an area; AVOID metal/electronics/water/pool/ocean b. Winter storms – snow, blizzard (heavy snow and wind), sleet, freezing rain Safety – stock up on gasoline, food, water, batteries, flashlights, blankets, warm clothes, snow shovel, and rock salt or other ice-melter c. Heat Wave – 3 or more days of temperatures above 90 F - wear light colored, loose fitting clothing, wear sunscreen, keep cool in air conditioning whenever possible, and drink lots of fluids d. Hurricane Safety – ___EVACUATE____ if advised, board up windows, listen for updates, watch out for flooding and high winds, prepare for blackouts, stock up on food and water. Also bring loose objects inside, or tie them down. e. Tornado Safety – If there is a tornado warning (means a tornado is in your area) or you see a tornado, go to a ___BASEMENT__ and listen to radio or TV for updates. If there is no basement, move to the center of the lowest level, away from windows. Sitting in a bathtub or closet with a mattress, blankets, or pillows protecting you from debris could also save your life. f. Lightening Safety – get in a car or building, if caught in an open area get LOW, stay away from _metal___, water, and tall objects. Weather Forecasting A. Typical Storm Tracks across the US go from __WEST___ to ___EAST__ because of the __jet stream / prevailing westerlies___ B. Based on typical storm tracks across the US, in which direction will this frontal system most likely travel?____toward the east or northeast______ 1. Predict upcoming changes in temperature and precipitation for cities A and B. Explain your answer. City A will soon be warmer, and should get rain since a warm front is approaching. City B will get cooler and have rain from the cold front. 2. Compare the temperatures in city B and city C. Explain your answer. City C should be colder, since the cold front already passed through it, but City B is still behind a warm front / is in a warm air mass. Typical Tracks of Hurricanes impacting the US are from __the Southern Atlantic Ocean__, and travel toward _Florida/the east coast/the gulf coast__ because of __the prevailing (easterly) winds__ C. Review of Hurricane Safety: a. What are some dangers that hurricanes pose? Strong winds, heavy rains, storm surges, and flooding b. What should you do if a hurricane is predicted for your area? Stock up on food, water, gasoline, batteries, and flashlights Bring all loose objects inside, or tie them down Board up your windows Evacuate if recommended to do so Severe Weather Awareness and Preparedness Hurricanes Define Hurricane- spinning tropical system with heavy rain, strong winds, and low pressure Hurricane Watch- a hurricane is POSSIBLE in your area in the next three days Hurricane Warning- a hurricane IS going to be in your area in the next 24 hours Storm Surge- large wall (wave) of water that moves onshore BEFORE A HURRICANE! (NOT A TSUNAMI! Tsunamis are caused by earthquakes) Hurricane Safety What should you do if there is a Hurricane Watch? Stock up on food and water, prepare to evacuate just in case, LISTEN to TV and radio for updates! What should you do if there is a Hurricane Warning? EVACUATE if told to do so, complete preparations, bring all loose objects (toys, chairs, etc) INSIDE, STAY INDOORS, and LISTEN TO TV and radio for updates What should you do DURING a hurricane to be safe? STAY INDOORS, and LISTEN TO TV and radio for updates Tornadoes Define Tornado- rapidly spinning funnel of wind Tornado Watch- A tornado is POSSIBLE for your area in the next few hours Tornado Warning- A tornado IS on the ground in your area Tornado Safety What should you do if there is a Tornado Watch? Get to a safe location and LISTEN TO TV and radio for updates What should you do if there is a Tornado Warning? Get in a basement, or a small interior room on the lowest floor, without windows, if no basement is available; You can also get in a bathtub or closet and cover yourself with blankets/pillows/etc What should you do DURING a tornado to be safe? STAY IN BASEMENT or small interior room (bathroom, closet, hallway) without windows and cover yourself with blankets/pillows/etc Lightning – What 4 things should you do DURING a lightning storm to be safe? Stay away from metal, STAY INDOORS, do NOT be the tallest object in an area, if outdoors, get low to the ground (in a ditch) and stay out of the water (pools/lakes/ocean), do NOT use a landline phone, do not take a bath or shower, unplug sensitive electronics,