1. Storms & Stuff Emma Gross Max Horwich Rod O’Connor

2. Formation and Life-Cycle Cumulus Stage: Masses of moisture are pushed upward. Moisture condenses into water droplets and becomes a cumulus cloud. The heat released by the condensation pushes the cloud higher and creates a low pressure zone underneath the cloud.

3. Formation and Life-Cycle Mature Stage: The warm air rises until it hits air that is already warm. Unable to rise further, it spreads out and takes on an anvil shape. Water droplets freeze to ice particles, which fall and melt on their way down, creating rain. If the updraft is strong enough, some droplets will not melt all the way, becoming hail.

4. Formation and Life-Cycle Mature Stage (continued): Falling rain and hail create down drafts. In combination with the already present up-drafts, these create turbulence within the storm causing lighting, strong winds, and occasionally tornados. If there is little change in wind speed or direction or wind sheer the storm will “ rain itself out ”, but if there is a lot of variance, the storm may become a super- cell.

5. Formation and Life-Cycle Dissipation Stage: Updraft conditions cease to exist. The storm is characterized mostly by weak downdrafts. Unable to sustain the storm cycle, the storm dissipates.

6. Types of Thunderstorms Single Cell: Atmosphere unstable, little or no wind sheer, precipitation cools updraft. Storms short lived, but can occur several times in one day.

7. Types of Thunderstorms Squall Line: An organized line of multi- cell storms, usually preceded by a gust front. Can be hundreds of miles long and have very severe winds. Tend to form near mountain ranges or linear weather boundaries.

8. Types of Thunderstorms Super-cell: Severe storms in which the updraft has become separated from the downdraft, creating a strong, rotating updraft called a mesocyclone. Can reach miles into the air. Most likely type of thunderstorm to produce tornados.

9. Severe Thunderstorms To classify as severe a storm must have: Wind 57.5 mph or greater Hail 3/4 inch diameter or greater Funnel clouds or tornados A storm which meets these criteria may not always be very dangerous, while some quite dangerous storms fail to classify as “severe”

10. Benefits Rainfall & Flooding: In tropics and subtropics, Almost all precipitation comes from thunder storms. Rain from storms contains particulate nutrients. Real rain is better for plants than artificially watering them. Floods due to storms deposit nutrient rich sediment in areas near rivers.

11. Benefits Winds Winds clear forests of old and dead trees and plants. Holes created in forest canopy, enabling new young plants to grow, and Storms keep the climate system running properly, keep the winters cool and summers warm.

12. Lightning Lightning converts air’s nitrogen to a form usable by plants, enabling them to complete photosynthesis. This nitrogen is called “fixed” nitrogen.(Some plants have bacteria that live in their roots to do this. Lightning causes forest and prairie fires which are apart of a healthy ecosystem. Individual plants and animals may suffer, but the system as a whole benefits. These fires create enable a diversity of species to exist in the various niches it carves.

13. How humans deal with storms Tornados: 70 fatalities and 1,500 injuries per year. Straight-line Winds: Just as damaging as tornados. Extremely dangerous to aviation. Lightning: 1318 deaths 1980-1995 (average 82 deaths per year). 300 injuries per year. Mostly in Texas and Florida. Odds of being struck by lightning: 1 in 700,000. Odds of being killed by lightning: <1 in 6 million.

14. Floods and precipitation Flash Floods –1,700 injuries, 140+ deaths per year –#1 cause of deaths associated with thunderstorms –Most fatalities occur at night and most victims are people who become trapped in cars –Six inches of fast-moving water can knock you off your feet; two feet of water will cause most vehicles to float Hail –Four hailstorms in July 1996 and 1998 in Calgary, Alberta caused total damages of $450,000+ –More than $1 billion in crop and property damage each year

15. Solutions and Prevention Shelters: 20,000-30,000 built since 1980 Approx. 10,000 lives saved every year due to shelters and emergency plans 36% of Americans do not have emergency preparedness plans What to do after a storm: Listen to radio, TV, NOAA Weather Radio for updated information and instruction Stay away from storm-damaged areas Watch out for fallen power lines and report them immediately Family Disaster Plan Gather information about hazards Learn what disasters can happen in your area Pick a meeting place in case you can’t return to your home