2 ObjectivesList and describe the main types of storms and explain how they formStandards:S6E4.b – Relate unequal heating of land and water surfaces to form large global wind systems and weather events such as tornadoes and thunderstorms.S6E4.c – Relate how moisture evaporating from the oceans affects weather patterns and the weather events such as hurricanes.
3 STORMS A storm is a violent disturbance in the atmosphere. They involve sudden changes in air pressure.Changes in air pressure causes rapid air movement (wind).
4 Thunderstorms Formation Temperature Precipitation Safety Within large cumulonimbus, or thunderheadsForm when warm air is forced upward at a cold frontTemperatureHot, humid afternoons in the spring and summerPrecipitationHeavy rainfallSometimes hailSafetyAvoid touching metal objectsInstall metal lightening rodsFind a low area away from treesStay away from water
5 ThunderstormsDuring a thunderstorm, positive and negative electrical charges build up in the clouds.The discharge of the electricity between clouds is lightening.Lightening is as hot as 30,000°C, hotter than the sun.The heated air expands and explodes producing thunder.
6 Checkpoint What is El Nino? What is a storm? Weather pattern related to the temperature of the water in the tropical Pacific Ocean.Any type of violent disturbance in the atmosphere.
7 TornadoRapidly whirling, funneled-shaped cloud that reaches down from a storm cloud to touch Earth’s surfaceMost frightening & disruptive stormUsually brief, touching the ground approx. 15 minutes or lessWind speeds may reach 480 km/hr
8 Tornado Formation Precipitation Safety Temperature Develop in low, heavy cumulonimbus cloudsWhen warm dry air mass and cool air mass collideTemperatureWarm humid airSpring and early summer when ground is warmPrecipitationHeavy rain and windSafetyListen for watches & warningsBasement level, or to the middle room on ground floorStay away from windowsLie in a ditch
9 Tornado Tornado Watch – tornadoes are possibly in your area Tornado Warning – tornadoes have been seen in the sky or on weather radarOccur most often in the USApprox. 800 tornadoes a year
10 Checkpoint Where do tornadoes form? Why is there a tornado valley? What states make up tornado valley?Low heavy cumulonimbus cloudsWarm humid air mass moves north from Gulf of Mexico and meets a cold dry mass that is moving south from CanadaSD, Iowa, Nebraska, Kansas, Missouri, Oklahoma, TX, NM, and Arkansas
11 Hurricanes Tropical storm that has winds of 119 km/hr Usually occur between June and November in the eastern USHurricanes that occur in western US are called typhoonsBring much needed rainfall to S Asia & SE Asia
12 Hurricanes Formation Temperature Precipitation Safety Begins over warm water as a low pressure area, tropical disturbanceGets its energy from warm humid air at the ocean’s surfaceTemperatureWarm temperaturesPrecipitationStrong windsRain which generally causes floodingSafetyEvacuateMove into the interior room and stay away from windows
13 Hurricanes Occur between June and November Effect people that live on the coast of the Atlantic, Pacific, and Indian OceansHurricanes bring needed rainfall to S Asia and SE AsiaEye – center of a hurricane
14 Winter StormsLake-effect Snow – In the fall and winter, land cools faster than the lakes.When cool air mass moves from Canada across Great Lakes it picks up water vapor and heat from lakes.After the air masspasses the lakes it beginsto cool and the water vaporcondenses and falls as snow