3 Thunderstorm Development Thunderstorms need:moisturewarm airlifting capability (fronts, sea breeze, mountains)Cumulus clouds (white, puffy) form from lifting air and develop into cumulonimbus clouds
4 LightningResults from buildup and discharge of electrical energy between + and – areas within a rising cloudLightning rapidly heats the surrounding air, causing a shock wave we hear as thunderThree types:Within cloudBetween cloudCloud-to-ground
8 Hurricane Life CycleStart as pre-existing low pressure systems, called tropical waves, over warm ocean watersEvaporating ocean waters and heated air rise and develop thunderstormsStorms begin to swirl around the low pressure center due to the Coriolis Effect (spinning of the Earth)
9 Hurricane StructureEye – sinking air in the center of the storm forms a calm, cloud-free eye that can be 20 – 40 miles acrossEyewall – dense thunderstorms surrounding the eye; strongest windsRainbands – thunderstorms and clouds that spiral outward from the center; spin counter- clockwise in the northern hemisphere
10 Hurricane StagesTropical Depression – strengthening tropical wave; winds less than 34 mphTropical Storm – continued strengthening; winds between 35 – 73 mph; namedHurricane – when winds reach 74 mph; eye formsHurricanes lose energy when they make landfall, or emerge into colder waters
11 Notice how this hurricane got worse over the dark red (warmer water) and finally died when it got over the colder water.
12 How Do You Measure a Hurricane? Hurricanes are measured by their speed and it is split into categoriesThe categories range from one to five, with one being the weakest and five being the strongestThe classification of hurricane systems is called the Safir- Simpson Hurricane Scale
13 Safir-Simpson Hurricane Scale Category One 74 to 95 MPHCategory Two to 110 MPHCategory Three to 130 MPHCategory Four to 155 MPHCategory Five Winds greater then 155 MPHNote: Hurricanes of Category Three or above are considered major hurricanes.
14 A storm surge is the change in sea level produced by wind pushing the water up onto the shore. It is the MOST damaging part of a hurricane.
15 Important Hurricane Terms A Hurricane Watch occurs when a hurricane is possible within 36 hoursThe storm is being tracked to predict where it may hitA Hurricane Warning is issued when it the storm is expected to hit within 24 hoursEvacuation may be needed
16 Hurricane Safety TipsKnow if the location you are in is a safe zone or whether evacuation may be neededProtect windows and glass with plywoodTurn off utilitiesHave a supply kit including first aid, water, canned goods, battery powered radio, blankets, etc.After evacuation, do not return until it has been declared safe
18 What is a Tornado?A tornado is a violently rotating column of air extending between, and in contact with, a cloud and the surface of the earthTornadoes can come one at a time or in clustersThey can also vary in size, length, width, direction of travel, and speed
19 Tornado FormationChanging wind direction and increased wind speed prior to a thunderstorm creates an invisible, horizontal spinning effect in the lower atmosphereRising warm air within the thunderstorm tilts the spinning air upward into the stormThe vertical spinning column of air begins to rotate the thunderstorm, and a tornado soon forms
21 The Enhanced Fujita Scale EF to 85 MPHEF to 110 MPHEF to 135 MPHEF to 165 MPHEF to 200 MPHEF Over 200 MPH
22 How Do You Measure a Tornado? Since February 1, 2008 tornadoes have been measured based on the Enhanced Fujita Scale (EF)This scale helps determine the speed of a tornado from weakest to strongest
23 Tornado FactsWaterspouts – tornadoes that form over water; usually weaker than land tornadoesTornadoes can be transparent, and only appear when dust and debris get picked up into the funnelTornadoes can occur anywhere on Earth, but are most common in “Tornado Alley” in the central United States
25 Tornado SafetyTornado Watch – conditions are right for tornado developmentTornado Warning – one has been sighted or indicated in the area; take shelterIf inside – stay away from windows, get in a central room or basementIf outside – seek shelter, get out of cars and get on the ground or in a ditch
26 More Severe Weather Flash Floods Heavy rainfall over a short period of time; causes most fatalities during thunderstormsHailStrong vertical winds within thunderstorm clouds (updrafts) carry rain drops to heights where they freeze; once they get too heavy they fall to the ground
27 SUN SAFETYThe Sun’s ultraviolet radiation can cause health risks, including skin cancerSurfaces like snow, water, and beach sand can double the effect of UV radiation