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THUNDERSTORMS THUNDERSTORMS Convective heavy rain accompanied by lightning and thunder
Ahrens Thunderstorms
About 1,800 T-storms occur around the world at any instant
Where do they occur the most?
National Lightning Safety Institute Thunderstorms
Satellite lightning frequency: flashes per km
2
per year
National Lightning Safety Institute Thunderstorms
Where do they occur the most? Thunderstorms
CUMULUS STAGE
Dr. M. Pidwirny, Dep. of Geography, Okanagan University College
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
UPDRAFTS Thunderstorms
MATURE STAGE
Dr. M. Pidwirny, Dep. of Geography, Okanagan University College
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS Thunderstorms
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
MATURE STAGE
NSSL Thunderstorms
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
MATURE STAGE
NSSL Thunderstorms
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
MATURE STAGE Thunderstorms
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
MATURE STAGE Thunderstorms
ORDINARY, AIR MASS, SINGLE CELL* THUNDERSTORMS
DISSIPATING STAGE
DOWNDRAFTS OCCUR
IN THE SAME AREA AS
THE UPDRAFTS
DISSIPATING STAGE (DOWNDRAFTS) Lightning facts: Breakdown potential: 3 MV/meter For a 1000 m strike, how much Volage needed? Can carry 30-40 kA The channel can reach 30000 degrees C The channel can be seen for over 100 mi. Thunder results from shockwave of exploding hot air channel Sound travels at ~330 m/s in air
one thousand one, one thousand two, one thousand three: Cloud to cloud, Intracloud, Cloud to ground (10%) Sprites and Jets Positive (10%) or negative charge (90%) Process leading to charge separation is complex
People still dont really understand how lightning rods work Lightning
Charge separation: Charges reside on the ice-crystal
surfaces During collision between particles,
charges get transferred Small ice crystals tend to acquire
net positive charge and then get
carried toward the cloud top Typical distribution of charges
shown, but it can be much more
complex The lightning process
1: Stepped Leader
A series of steps about 50
meters (160 ft) in length and 1
microsecond (0.000001
seconds) in duration.
Studies of individual strikes
have as many as10,000 steps!
2: Upward streamer
Induction causes positive
charges to trace an upward
path from high, sharp points
until channels meet
3: Connection
Ionized path allows easy-flow of
charge downward from cloud to
surface
4: Return stroke
Positive charge from the ground
flows back upward along the
path. This is where most of the
current is: 30000 Amps
produces heat, glow, and
thunder Thunderstorms
HAIL Thunderstorms
HAIL Thunderstorms
HAIL Thunderstorms
1970 Coffeyville KA hailstone Thunderstorms
HAIL DAMAGE Thunderstorms
HAIL DAMAGE