Section I- Weather Systems

What are the stages of thunderstorm development?

• cumulus and developing stages

• mature stage

• dissipation stage

cumulus and developing stages

• begins with convection where rapid rising air forms cumulus clouds

• developing stage: condensation releases latent heat

• dominated by updrafts

mature stage

• hot rising air leads to delepoment of strong updrafts

• intense precipitation vrings cold air down to create downdrafts

• updrafts and downdrafts co-exist

• note the “anvil head" on the storm

dissipation stage

• dominated by downdrafts

• light rain/ rain ends

What is lightning?

electrical discharge produced by thunderstorms

intercloud

cloud to cloud

intracloud

within a single cloud

percentage of intercloud and intracloud

75%

percentage cloud to ground

25%

What does the collisions among ice crystals and rain droplets cause?

difference in electrical charge within clouds

What are the charges during a ligtning?

• +ve particles are high in the cloud, -ve particles concentrate in the base

• has +ve charge

How is lightning (spark) created?

in strong storms, leader (-) from cloud meets streamer (+) from ground, creating “spark” as cloud-to-ground lightning

Define thunder

expansion of air caused by abrupt heating that lightning produces

odds of being struck vary from person to person depending on several factors: (3)

• geographical location

• climate

• personal lifestyle/ hobbies

  • ex.) Ranger Roy Sullivan, golfers

How do you determine the distance of a lightning bolt?

• count number of seconds till thunder occurs

  • divide by 3 to get distance in km

What is the 30/30 rule during a thunderstorm? (6)

• always shelter indoors if possible

• if outdoors, do not be the highest object or stand under highest trees

• crouch low, with little of your body touching the ground as possible

• being inside a car is safe

• stay away form water, no boating

• wait 30 min after storm has passed

What clouds are associated with thunderstorms?

• shelf cloud

• mammatus cloud

What is a self cloud?

could downdraft within a storm surges along the ground, lifting warmer air ahead of the storm to the LCL and forming a shelf

What are mammatus clouds?

found at the base of a spreading anvil downwind of a large thunderstorm, may be related to pockets of cold air that move down into warmer air

Where do severe thunderstorms develop?

where there is an abundance of warm, moist air and strong convective activity, unstable air

What are severe thunderstorms associated with?

midlatitude cyclones

Severe thunderstorms contain mesocyclones, which are:

vertically rotating cylinder of air/ a horizontal vortex of air pulled vertically in updrafts

violent storms may produce:

• damaging wind

• hail

Mesocyclones require what to form?

wind shear -winds moving in different direction or with different speeds

What are tornados?

• low pressure cylinder that spin so quickly a partial vacuum develops withing the funnel

• are usually less than 400 m in diameter but have extreme pressure gradients

• damage: caused by strong winds and flying debris

When is peak tornado season in North America?

between April and July

Regional names of tropical cyclones (3)

• typhoon (western north pacific)

• cyclone (Indian ocean)

• hurricane (N. America)

What are tropical cyclones fueled by?

abundant water vapor and latent heat- +ve feedback

What’s the environmental requirements for tropical cyclone development: (6)

• warm ocean surface (>27 degrees C)

• high evaporation rate

• minimal to no wind shear

• high pressure aloft

• Coriolis effect (min. of 5-10 degrees away from the equator)

  • 7 degrees to 15 degrees N and S latitudes

• often develop from tropical/ easterly waves in the Atlantic

disturbance- tropical cyclone development

tropical depression

pressure drops in the center

tropical cyclone

• >119 km/hr

• spiral rain ba

anatomy of a tropical cyclone !!!

maybe write in notes

What is the official hurricane season?

• June 1st - November 30th

• peak: mid August - mid October

About the Atlantic Hurricane Tracks:

• originate in west Africa, driven by trade winds

• intensify over warm tropical Atlantic

• driven northeast by westerlies

• blocked by high pressure in Atlantic

Tropical cyclone damage and destruction: (5)

• storm surge

• high winds

• torrential rain and inland flooding

• tornadoes

• rip currents

What are storm surge? (2)

• pressure and wind component

• most hurricane related deaths are drownings

Rates hurricane storm strength range from:

1-5