Thunderstorms, Lightning, and Tornadoes

Conditions for T-storms

• uplift

• moisture in the air

• instability

Air Mass T-storm: Updrafts

convection causes uplift and condensation increases strength of uplift

Air Mass T-storms: Downdrafts

precipitation pulls air down from higher in the troposphere

Air Mass T-storms duration

a little over an hour with little storm movement

Severe T-storms: Updrafts

initiates in warm sector of mid-latitude cyclones and condensation increases strength

Severe T-storms: Downdraft

precipitation pull air down from higher in the troposphere

Severe T-storms: Duration

about 4 to 10 hours of self-propagating movement

What is Classified as Severe Weather

• winds greater than 93 km/h

• hailstones larger than 1.9cm

Storm Watch

T-storms and tornadoes are possible in the current weather conditions

Storm Warning

T-storms and tornadoes are occurring or imminent

Lightning

acts to reduce the electrical gradient from the clouds (negative) to the ground (positive)

Sheet Lightning

lightning that appears from cloud to cloud (80% of the time)

Thunder

rapid heating by lightning causes explosive expansion of air

Characteristics of Tornadoes

• winds 40 - 280 mph (Fujita scale)

• lasts several minute to several hours

• most common in flat areas

• most frequent in areas that have temp. clashes