logging in or signing up Weather Forecasting and Air masses-1 GECA Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 183 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: May 05, 2009 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Air Masses, Fronts and Global Wind Patterns : Air Masses, Fronts and Global Wind Patterns Meteorology Air Masses : Air Masses Definition: : Definition: Air mass - a large dome of air which has similar horizontal temperature and moisture characteristics throughout. Very similar to a balloon. Continental Arctic (cA): : Continental Arctic (cA): Frigid – record low temperatures Dry - very low dew points Dense - very high barometric pressure Usually originate north of the Arctic Circle Siberian Express Usually once or twice a winter very rarely form during the summer because the sun warms the Arctic. Continental polar (cP): : Continental polar (cP): Cold and dry - stable Usually originates in NW Territory of Canada Influences mainly the northern USA Responsible for clear and pleasant weather during the summer Usually in winter Creates troughs in the polar jet stream Lake effect snow in Great Lakes areas Maritime polar (mP): : Maritime polar (mP): Cool and moist - unstable Originate over N. Atlantic and N. Pacific Main Influence - the Pacific Northwest and the Northeast. can form any time of the year Generally not as cold as cP air masses Maritime tropical (mT): : Maritime tropical (mT): Warm and very moist – unstable Originate in the Gulf of Mexico and the Southern Atlantic Ocean Influences the eastern USA Most prevalent during summer Responsible for hot, humid summer days across the South and the East. Continental Tropical (cT): : Continental Tropical (cT): Very Hot and very dry – stable aloft Originates in Desert Southwest and northern Mexico Occurs in the summer, rarely in winter Usually keeps the Desert Southwest scorching above 100oF during summer Generally clear skies, hot, low humidity Source Regions : Source Regions Reasoning for Tornadoes : Reasoning for Tornadoes Orographic Perfection Meeting of Moist - mT Hot - cT Cool – cP Rocky Mtn. Tornado Alley : Tornado Alley http://www.britannica.com/thunderstorms_tornadoes/video/ocliwea124v4.mov Fujita Scale : Fujita Scale (NationalAtlas.com) Fronts and their symbols : Fronts and their symbols Fronts: : Fronts: Boundary between two air masses Characterized by shift in weather Cold Warm Stationary Occluded 5 Characteristics of a Front : 5 Characteristics of a Front Sharp temperature changes over a relatively short distance. Changes in air moisture content Shifts in wind direction Pressure changes Clouds and precipitation Cold Fronts : Cold Fronts Temperature – drops rapidly Pressure – rises steadily Clouds – Vertical building Precipitation – Heavy along front Winds – Strong and shifting Typically move faster than warm front Cold Front : Cold Front Slide 20: (Fozzy) Cold Front Cold Front : Cold Front In the summer, cold fronts can trigger: : In the summer, cold fronts can trigger: thunderstorms large hail dangerous winds tornadoes Graphic Depiction! : Graphic Depiction! Warm Fronts : Warm Fronts Temperature – rises slowly Pressure – slight rise, then fall Clouds – strato- and cirro- Precipitation – long, steady Winds – variable and light Typically will have affect for days Warm Front : Warm Front Warm Front : Warm Front Warm Front : Warm Front Effects of warm fronts : Effects of warm fronts Slow-moving warm front can mean days of wet weather before warm air Sometimes water vapor in warm fronts condense to produce rain snow sleet freezing rain Stationary Front : Stationary Front Stationary Fronts : Stationary Fronts Temperature – stagnent Pressure – slightly fluctuates Clouds – altocumulus Precipitation – none Winds – variable and light Can last for days weeks Occluded Front : Occluded Front Occluded Fronts : Occluded Fronts Temperature – Warm – gets milder Cold – gets colder Pressure – Warm - slight drop Cold – slight rise Clouds – cumulus Precipitation – steady and light Winds – variable and light Occluded Front : Occluded Front Slide 35: Different Temperatures - Different Pressures Cool Air Warm Air Denser More Pressure Less Dense Less Pressure Pressure and Air Movement : Pressure and Air Movement Pressure Gradient Force : Pressure Gradient Force Difference in pressure over a given distance---between isobars Close together = step pressure gradient STRONG winds Far apart = gentle pressure gradient Light winds Just like contour lines Pressure Gradient Force : Pressure Gradient Force Isobaric Maps : Isobaric Maps Coriolis Effect : Coriolis Effect Apparent force due to the rotation of the Earth (Think Merry-go-round) N. Hemisphere ? wind turns right S. Hemisphere ? wind turns left Strength depends on latitude and wind speed Slide 41: Coriolis Effect Coriolis Effect : Coriolis Effect Centripetal Force : Centripetal Force In-ward directed force Allows an object to remain in circular motion Winds moving around high and low pressure areas Clockwise around Highs. Counter-clockwise around Lows. Friction (What a Drag) : Friction (What a Drag) The resistance to movement Surface winds are affected by friction Why? Ground resistance: trees, mountains, houses, buildings, etc. This drag causes winds to blow across pressure gradient at the surface. Pressures All Together : Pressures All Together Slide 48: General Planetary Circulation Winds : Winds Horizontal movements at surface Names from WHERE it came from…not where it is going!!! Around Pressure Cells : Around Pressure Cells Pressure Cells : Pressure Cells High – In and Up Converge at surface Ascend in center Diverge Aloft Low – Down and Out Converge aloft Descend in center Diverge at surface X-section of Planetary Circulation : X-section of Planetary Circulation January Global Pressure Map : January Global Pressure Map January July Global Pressure Map : July Global Pressure Map July Summer Highs : Summer Highs You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Weather Forecasting and Air masses-1 GECA Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 183 Category: Entertainment License: All Rights Reserved Like it (0) Dislike it (0) Added: May 05, 2009 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Air Masses, Fronts and Global Wind Patterns : Air Masses, Fronts and Global Wind Patterns Meteorology Air Masses : Air Masses Definition: : Definition: Air mass - a large dome of air which has similar horizontal temperature and moisture characteristics throughout. Very similar to a balloon. Continental Arctic (cA): : Continental Arctic (cA): Frigid – record low temperatures Dry - very low dew points Dense - very high barometric pressure Usually originate north of the Arctic Circle Siberian Express Usually once or twice a winter very rarely form during the summer because the sun warms the Arctic. Continental polar (cP): : Continental polar (cP): Cold and dry - stable Usually originates in NW Territory of Canada Influences mainly the northern USA Responsible for clear and pleasant weather during the summer Usually in winter Creates troughs in the polar jet stream Lake effect snow in Great Lakes areas Maritime polar (mP): : Maritime polar (mP): Cool and moist - unstable Originate over N. Atlantic and N. Pacific Main Influence - the Pacific Northwest and the Northeast. can form any time of the year Generally not as cold as cP air masses Maritime tropical (mT): : Maritime tropical (mT): Warm and very moist – unstable Originate in the Gulf of Mexico and the Southern Atlantic Ocean Influences the eastern USA Most prevalent during summer Responsible for hot, humid summer days across the South and the East. Continental Tropical (cT): : Continental Tropical (cT): Very Hot and very dry – stable aloft Originates in Desert Southwest and northern Mexico Occurs in the summer, rarely in winter Usually keeps the Desert Southwest scorching above 100oF during summer Generally clear skies, hot, low humidity Source Regions : Source Regions Reasoning for Tornadoes : Reasoning for Tornadoes Orographic Perfection Meeting of Moist - mT Hot - cT Cool – cP Rocky Mtn. Tornado Alley : Tornado Alley http://www.britannica.com/thunderstorms_tornadoes/video/ocliwea124v4.mov Fujita Scale : Fujita Scale (NationalAtlas.com) Fronts and their symbols : Fronts and their symbols Fronts: : Fronts: Boundary between two air masses Characterized by shift in weather Cold Warm Stationary Occluded 5 Characteristics of a Front : 5 Characteristics of a Front Sharp temperature changes over a relatively short distance. Changes in air moisture content Shifts in wind direction Pressure changes Clouds and precipitation Cold Fronts : Cold Fronts Temperature – drops rapidly Pressure – rises steadily Clouds – Vertical building Precipitation – Heavy along front Winds – Strong and shifting Typically move faster than warm front Cold Front : Cold Front Slide 20: (Fozzy) Cold Front Cold Front : Cold Front In the summer, cold fronts can trigger: : In the summer, cold fronts can trigger: thunderstorms large hail dangerous winds tornadoes Graphic Depiction! : Graphic Depiction! Warm Fronts : Warm Fronts Temperature – rises slowly Pressure – slight rise, then fall Clouds – strato- and cirro- Precipitation – long, steady Winds – variable and light Typically will have affect for days Warm Front : Warm Front Warm Front : Warm Front Warm Front : Warm Front Effects of warm fronts : Effects of warm fronts Slow-moving warm front can mean days of wet weather before warm air Sometimes water vapor in warm fronts condense to produce rain snow sleet freezing rain Stationary Front : Stationary Front Stationary Fronts : Stationary Fronts Temperature – stagnent Pressure – slightly fluctuates Clouds – altocumulus Precipitation – none Winds – variable and light Can last for days weeks Occluded Front : Occluded Front Occluded Fronts : Occluded Fronts Temperature – Warm – gets milder Cold – gets colder Pressure – Warm - slight drop Cold – slight rise Clouds – cumulus Precipitation – steady and light Winds – variable and light Occluded Front : Occluded Front Slide 35: Different Temperatures - Different Pressures Cool Air Warm Air Denser More Pressure Less Dense Less Pressure Pressure and Air Movement : Pressure and Air Movement Pressure Gradient Force : Pressure Gradient Force Difference in pressure over a given distance---between isobars Close together = step pressure gradient STRONG winds Far apart = gentle pressure gradient Light winds Just like contour lines Pressure Gradient Force : Pressure Gradient Force Isobaric Maps : Isobaric Maps Coriolis Effect : Coriolis Effect Apparent force due to the rotation of the Earth (Think Merry-go-round) N. Hemisphere ? wind turns right S. Hemisphere ? wind turns left Strength depends on latitude and wind speed Slide 41: Coriolis Effect Coriolis Effect : Coriolis Effect Centripetal Force : Centripetal Force In-ward directed force Allows an object to remain in circular motion Winds moving around high and low pressure areas Clockwise around Highs. Counter-clockwise around Lows. Friction (What a Drag) : Friction (What a Drag) The resistance to movement Surface winds are affected by friction Why? Ground resistance: trees, mountains, houses, buildings, etc. This drag causes winds to blow across pressure gradient at the surface. Pressures All Together : Pressures All Together Slide 48: General Planetary Circulation Winds : Winds Horizontal movements at surface Names from WHERE it came from…not where it is going!!! Around Pressure Cells : Around Pressure Cells Pressure Cells : Pressure Cells High – In and Up Converge at surface Ascend in center Diverge Aloft Low – Down and Out Converge aloft Descend in center Diverge at surface X-section of Planetary Circulation : X-section of Planetary Circulation January Global Pressure Map : January Global Pressure Map January July Global Pressure Map : July Global Pressure Map July Summer Highs : Summer Highs