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Storms & Stuff
Emma Gross
Max Horwich
Rod O’Connor
Formation and Life-CycleCumulus 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.
Formation and Life-CycleMature 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.
Formation and Life-CycleMature 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.
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.
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.
Types of ThunderstormsSquall 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.
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.
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”
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.
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.
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.
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.
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
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 plansWhat 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
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