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Montclair EAES 104 - Thunderstorm and Tornado Powerpoint Presentation

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Thunderstorms and TornadoesThunderstormsThunderstorms Ingredients for Cooking up the StormSlide 4Slide 5Slide 6Slide 7Life Cycle of A ThunderstormSlide 9Slide 10Slide 11LightningSlide 13ThunderHailSlide 16TornadoesSlide 18Slide 19Slide 20Slide 21Slide 22Slide 23Tornado CharacteristicsSlide 25Slide 26Slide 27Tornado HazardsSlide 29Tornado OutbreakThunderstorms and TornadoesChapter 15Thunderstorms and TornadoesEXTREME WEATHER PHOTOSThunderstormsViolent, local atmospheric disturbance that mostly last only 30 minutes, but can create several dangerous phenomena: Torrential rain: usually intense, but short in duration - flash flooding and slope failure in mountainous terrain is often associated with this type of precipitation. High wind: Winds at the surface beneath a thunderstorm can reach well over 50 mph (80 kph). Hail: falling at several meters per second, hail stones can result in extensive damage to crops and property in just a few minutes and can injure or kill. Lightning: every year in the U.S., lightning is responsible for an average of almost 100 deaths and 300 injuries. Lightning frequently starts fires which threaten homes, businesses, and lives. Power and communication outages caused by lightning (as well as wind) can result in large scale disruption of everyday activities.Tornadoes:ThunderstormsIngredients for Cooking up the StormSources of Moisture, A Lifting Mechanism, andInstability. All thunderstorms require three ingredients for their formation: Above and Right: Life Cycle of a ThunderstormSources of moisture It is estimated that there are as many as 40,000 thunderstorm occurrences each day world-wide, most occurring in latitudes near the equator. Late afternoon hours in Spring and summer bring the greatest risk of thunderstorms to most of North America. Right: The figure to the right shows the average number of thunderstorm days each year throughout the U.S. The greatest frequency of occurrence is in the southeastern states, with Florida having the highest incidence. ThunderstormsIngredients for Cooking up the StormLeft: Typical sources of moisture are large bodies of water such as the Atlantic and Pacific oceans as well as the Gulf of Mexico. The southeastern U.S. has access to two moisture sources in the Atlantic ocean and the Gulf of Mexico which helps explain why there are so many thunderstorms in that region.ThunderstormsIngredients for Cooking up the StormA Lifting Mechanisma. Convergent, b. Convective,c. Orographic, d. FrontalThunderstormsIngredients for Cooking up the StormCold air pushing under warm air along a cold front is a common lifting mechanism.Below: A squall line is a line of thunderstorm which typically forms along the leading edge of a cold front.ThunderstormsIngredients for Cooking up the StormAtmospheric InstabilityAbove: Unstable air - air parcel forced aloft cools slower than the surrounding environment and continues to rise because it is warmer and more buoyant than its surroundings. Right: Clouds of vertical development form.Life Cycle of A ThunderstormCumulus StageA cumulus cloud begins to grow vertically. Air within the cloud is dominated by updraft. Below: Thunderstorms begin when a parcel of warm, moist air rises and cools adiabatically until it reaches saturation and forms a fluffy cumulus cloud. As this moisture condenses, it releases heat and warms the air parcel more, causing more uplifting.Mature Stage The storm is at its most intense stage of development and is now a cumulonimbus cloud. The top of the cloud reaches the tropopause where upward motion is hindered and the cloud spreads out horizontally. Life Cycle of A ThunderstormRight: Mature thunderstorm cloud with typical anvil shaped cloud.Mature StageStrong updrafts and downdrafts coexist. The mature air mass thunderstorm contains heavy rain, thunder, lightning, and produces wind gusts at the surface.Life Cycle of A ThunderstormRight: When the updrafts reach their maximum altitude precipitation begins to form. The falling rain causes a drag on the air, and a downdraft is created.Dissipating StageThe thunderstorm enters the dissipating stage as the supply of warm moist air is depleted. Air currents within the convective storm are now mainly downdrafts. Light rain and weak outflow winds may remain for a while during this stage, before leaving behind just a remnant anvil top (below).????????????????????????????????????????????????????????????????????Life Cycle of A ThunderstormLightningLightning occurs when thunderstorms concentrate positive electrical charges in the upper part of cumulonimbus clouds and negative charges in the lower part. When the difference in the charge become great enough to overcome air resistance, a sudden and visible violent electrical discharge occurs in the form of a lightning stroke.These two brothers didn't recognize the danger they were in. Their hair is standing on end from a thunderstorm-induced electrical charge. The two brothers, and their sister, were killed moments later when lightning struck.Lightning ImagesThe electrical discharge can be within clouds and/or between the cloud and ground. Left: Cloud-to-ground lightning is initiated by the downward-moving leader stroke. Multiple cloud-to-ground and cloud-to-cloud lightning strokes are observed during a night-time thunderstorm at left.Right: Ground-to-cloud lightning is a lightning discharge between the ground and a cumulonimbus cloud from an upward-moving leader stroke.ThunderThe lightning heats the surrounding air to about 30, 000 degrees Celsius, which expands at supersonic speeds, creating the mighty crashes we recognize as thunder. Lightning and thunder happen at exactly the same time, but you see the lightning before you hear the thunder because light travels faster than sound.HailHailstones appear when warm humid air in a thunderstorm rises rapidly into the upper atmosphere and freezes forming tiny ice crystals. If the updraft is strong enough, the ice crystals can rise and fall many times, with the hail getting new coats of water which then freeze, making the hail grow. When the hail is too heavy to be sustained in the air by the updraft, it falls to earth.Flash FloodsA short lived upstream flood characterized by rapidly rising, high velocity water.TornadoesA tornado is a violently rotating funnel of air spawned from supercell thunderstorms. 3 main atmospheric conditions must occur simultaneously to produce a tornado1) a northerly flow of warm, moist air from the


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Montclair EAES 104 - Thunderstorm and Tornado Powerpoint Presentation

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