1. Inland Storms

2. Atmospheric (barometric) PressureAtmospheric pressure is the weight of a column of of air over a given point. 3. WindWind is caused by differences in atmospheric pressure, as air flows from areas where theatmosphere is thicker (high P) to those where its thinner (low P). Pressure gradients arecaused mostly by differential heating of the earths atmosphere and surface. 4. Pressure CellsThick masses of dry air move downward in high pressure cells andexpand outward. Air converges inward toward the center of low pressurecells and then rises, condensing to form clouds. 5. Global Differential HeatingBecause of earths spheroidal shape, a given amount of solar energy willis spread over a larger area at the poles than along the equator. 6. Atmospheric ConvectionDifferentialheating of theearths surfaceresults in large-scaleatmosphericconvection cellsthat stretch fromthe equator to thepoles and back. 7. Coriolis EffectBecause of earthsrotation, atmosphericand oceanic currents aredeflected clockwise inthe northern hemisphereand counter-clockwise inthe southern, givingthese currents a curvedpath. There is nodeflection at the equator. 8. Prevailing Wind PatternsA combination of differential heating and the Coriolis Effect produceglobal-scale prevailing wind patterns. 9. Global Pressure CellsDisruption of prevailing wind patterns by continental masses leads to theformation of pressure cells, which play a major role in global andregional weather patterns. 10. Regional Differential Heating(altitude)During the day, atmospheric molecules are heated, lowering their densityand causing them to rise. At night time, these particles cool, increase indensity, and descend. 11. Regional Differential Heating(surface materials)Different surface materials, such asland and sea or land and ice, havedifferent capabilities of absorbingand retaining heat, leading to lateralchanges in air density. 12. FrontsCold front: cold air advancestoward warm air, forcing thewarm air to rise.Warm front: warm airadvances toward cool air andrises over cold mass.Stationary front: littlemovement between air masses.A front is the boundary between air masses of different densities, usually cool and warm. 13. Thunder Storms 14. Thunder Storm StructureThunderstorms form as warm, moist air rises rapidly, passes over coldair, and cools at higher altitudes, producing clouds and precipitation.They occur most commonly during the afternoon and evening hours ofspring and summer. 15. Photo by W. W. Little 16. Rain forms from either the melting of ice crystals and snowflakes fallingfrom higher altitudes or from the coalescence of smaller water droplets. 17. http://img139.imageshack.usHailhttp://www.rapiddent.com.au/images/HailFormation.jpg NOAAHail is produced as ice passes up and down within a cloud. At lowerlevels it becomes coated with water that freezes when taken to higheraltitudes, forming concentric rings. 18. LightningLightning is a flash of light that occurs as electricity is discharged fromelectrically-charged clouds. Surrounding air can be heated to 30 K0 C,5X the temperature of the Suns surface. Rapid expansion ofsurrounding air produces thunder. 19. Clouds become electrically charged asice crystals move vertically past oneanother. A negative charge at thecloud base drives away negativeparticles at the ground surface anddraws positive particles upward. 20. About 80% of lightning occurs between clouds. 21. Thunderstorm OccurrenceIn the U.S., thunderstorms are most common along the Gulf Coast,followed by the Front Range of Colorado and New Mexico. Globally,Uganda has the record with a storm 7 out of every 10 days. 22. TornadoesTornadoes form as part of supercell thunderstorms as the warm updraftproduces a powerful vortex. 23. Tornado DevelopmentTornadoes form as irregularities along a major front (boundary between coldand warm air masses) allow rotation to begin as warm air rises and cold airdescends, forming a vortex. The vortex becomes visible as moisturecondensates or it gathers dust. 24. Tornado Outbursts 25. Tornado StagesWall Cloud Funnel CloudMature Waning 26. Tornado Occurrencehttp://www.nssl.noaa.gov/primer/tornado/imagesTornadoes occur worldwide and have been reported from all fifty states.However, by far the most common occurrence globally is in Tornado Alleyof the United States. This is due to a unique set of weather conditions that leadto regular mixing of cold and warm air masses, along with an abundantmoisture supply. 27. Fujita Intensity ScaleIn 1971, T. Theodore Fujita created a scale (often called the F scale) formeasuring intensity. Like the Mercalli Scale for earthquakes, the Fujita Scalemeasures the degree of damage. 28. Mitigation: Early Warning(Doppler Radar)Doppler Radarbounces radar wavesoff of rain droplets,measuring theirabundance, size, andmovement with theobjective of spottingcloud rotation.Doppler gives anaverage warning timeof 13 min. 29. Mitigation: Early Warning(Amateur Weather Watchers)A program designed to teach amateur radiooperators how to identify and report severeweather that might or might produce atornado to the National Weather Service 30. Mitigation: Early Warning(Emergency Broadcast/Alert System) Begun in the 1950s to give warning of potential hazardous conditions,including weather alerts. For tornadoes, a warning will be issued when: A tornado has touched the ground A funnel cloud is reported Radar picks up low level rotation A waterspout is heading toward land 31. Mitigation: Early Warning(Sirens) 32. Mitigation: Early Warning(Storm Chasers)Storm chasers use special equipment to locate storms before they develop and studythem once they do. 33. Mitigation: Shelters 34. Mitigation: Research(TOTO old school)Built by NOAA from 1979 to 1987.Would fall after contact with tornado,deploying sensors that would be pulledinto the tornado. 35. Mitigation: Research(Storm Research Vehicles new school)The SRV Dominator is a modified 2011 GMC Yukon with armor, anchors, and a rollcage for protection and a vertical radar and compressed-air launchers for parachutedprobes to study wind characteristics. It is designed to be directly in the path of atornado. 36. Mitigation: Building CodesHurricane ties. 37. Cold-weather StormsAs temperatures drop, rain can change to freezing rain, sleet, and snow,creating a variety of hazardous weather conditions. 38. Freezing RainFreezing rain occurs when surface temperatures are below freezing, but theatmosphere is above. Rain falls through the sky and turns to ice upon hittingthe ground. 39. Snow Storms & BlizzardsSnow is the result of a thick column of cold air immediately above the earthssurface. Blizzards occur if the snow is accompanied by high winds. 40. Snow FlakesSnow flakes form as water vapor (not liquid) freezes upon contact with dust orsmall ice crystals, growing into hexagonal structures large enough to fall tothe surface. Humidity and temperature determine the type of snow flake, suchas Utahs powder and Missouris mush.