GEOG 111 1st Edition Lecture 36 Outline of Last Lecture I. Tornadoesa. Characteristicsb. Super cell thunderstormsOutline of Current Lecture I. Tornadoes and their attributesa. Tornado StrengthII. Tornado developmentIII. Geographic distributionIV. Seasonal DistributionV. Tornado damage and safetyCurrent LectureI. Tornadoes and their attributes (continued)a. Tornado strength (F-0 to F-6)i. As F-scale rating increases, damage, frequency, size and duration increase as well1. Large tornados move the quickestii. Irregular patterns from one year to yeariii. Strong tornadoes concentrated in tornado outbreaks (days with lots of activity)iv. Weak tornados occur frequently and for a short amount of timev. Determining strength1. Work with structural engineers to assess damage after the tornadovi. F-4 and F-5 tornados typically consist of multiple vortices1. Winds spinning counterclockwise2. Many tornados are nested within a broader tornadoII. Tornado developmenta. Wave cyclone circulation (counterclockwise)b. Warm moist air feeding into the system at the warm sectorc. Directional shear- winds are blowing different directions as you go up through the columni. Winds are also blowing faster in the upper part of the columnd. Tornados occur in the warm sectori. Instability: warm moist air in the lower levelsii. Trough approaching: cooling of column in middle and top part of the column1. ELR is steeper so thunderstorms readily developiii. Combine these factors with the wind shear1. Speed shear causes tornado genesis2. Rolling wind hits updraft and is translated into the verticalThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.3. Connect with mesoscale circulationIII. Geographic distributioni. Correlates with terrainii. Need well-organized rolls on the surface that’s not too rough1. Mountains and hills inhibit lower level convergence and thunderstorm development2. Less tornadoes in the western part of the country3. Maximum in the southern Great Plainsa. Presence of dry air aloft 4. More tornadoes in North America than other continentsa. No mountains in the Eastern part that could block warm moist air from the Atlantic and Gulfb. No East to West mountain ranges (like the Himalayans)IV. Seasonal distributiona. Spring maximum (early May)i. Correlates with jet stream strength/position (strong winds aloft, greater wind shear) and instabilityV. Tornado damage and safetya. Strong winds and flying debrisb. Pressure differences produce strong upliftc. Stay in an interior room that has no windows and is closed off completelyi. Bathrooms are a little bit more safe because of the plumbing and greater structural support ii. Lowest level of the buildingd. Mobile homes are most deadlyi. Account for 45 percent of all tornado-related deathse. In a car, never try to outdrive a tornadoi. They change directions quickly and can lift up a car and toss it through the airii. Get out of the car as soon as possible and seek shelter in a building, if not lie in aditch away from the
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