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Learn about the formation of thunderstorms and tornadoes, including the role of air masses, surface heating, and unstable air. Explore the terms associated with these weather phenomena and understand why they can be dangerous. Discover the paths and origins of tornadoes.
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Air Mass Thunderstorms Surface heating! The source for all unstable air rising! • As air is forced to rise, it accumulates, creating lots of rising moist air • Air that is forced to rise and cool quickly will try to stabilize – thunderstorm • Late afternoon thunderstorms in the summer
Stage A – Rising air from surface heating • Stage B – Sinking air that has cooled. Cold air wants to be at the surface • Stage C – No more rising air means no more power for the storm, and the storm “dissipates”
Terms • Gust Front: (aka outflow boundary) the edge of gusty, cooler surface winds from thunderstorm downdrafts – we feel this often from approaching thunderstorms • Squall Line: line of thunderstorms that can form along or ahead of a cold front
Severe Thunderstorms • Associated with frontal zones • WHY? TURBLENCE! • Cold front advances on a warm front • Also seen during Occluded front • Tornadoes can be associated with these storms
Tornadoes http://www.geo.hunter.cuny.edu/~tbw/wc.notes/10.thunderstorms.tornadoes/animations/nTwinds.html
Tornadoes • Another response to unstable air • Also called “funnel clouds” • http://www.spc.noaa.gov/faq/tornado/ • Mesocyclonesform from supercells--which are rotating thunderstorms with a well-defined circulation • Cyclone = low pressure. Tornadoes can be as low as 100mb
Tornado Paths • Typically from SW NE in the US • WHY? Where is the warm moist air coming from? • Air moves from H L