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