GY 101 TEST 4

Hurricane

120km/h winds

Fujita scale F4-F5:

3% of tornadoes; 70% of deaths

Tropical Storm

60km/h winds (receives name)

Fujita scale F0-F1:

69% of torandoes; 5% of deaths

Storm surge

A dome of water that sweeps across the coast where a hurricane lands

Atlantic Season

June 1 - November 30

Hurricane Atlantic Season

June-november peak: mis august-early october

Squall lines

Long lines of thunderstorms that form along a cold front linear multi cell storms frontal or pre-frontal vertical tilt increases severity moist low level S or SE inflow mid level flow larger 25 knots

Tornadoes

as cumulonimbus clouds rise high into the troposphere, the bottom winds move slow due to surface friction, but the upper winds move fast results in rotation of air parallel to the ground updrafts or downdrafts can cause the vortex to become vertical

Hurricane movement and dissipation

controlled by large surface pressure systems controlled by upper level flow will dissipate over land or colder water

Hurricane development

coriolis force -atlantic formation usually between 10-20N water above 27C little wind shear

Tornado safety

find a safe place away from windows do not stay in your car if outside, lay flat or find a ditch

Lightning

flases of light caused by enormous electrical discharges superheats the air abruptly resulting in enormous shock waves (thunder)

Supercell

high threat intense updraft (almost always severe) mesocyclone present tornadoes are common and located balanced updraft and downdraft low level mesocyclogenesis more likely moderate hook echo

Hail

ice pellets only occur with cumulonimbus clouds

Ingredients for a thunderstorm

lift from -cold/warm front -gust front -daytime heating low-level moisture instability wind shear

The storm surge in a hurricane comes from

low pressure

Tornado locations

mainly in North America, Great Plains, Southeast, some can be seen in Japan, South Korea

Tropical Depression

one closed isobar (receives number)

Sea Level Pressure (SLP)

pressure measured at sea level less than 990 mb

Single Cell (pulse)

slight threat weak updraft (non-severe or strong updraft) moves with mean environmental wind over 5-7km 30-60 min duration rainfall can be moderate to heavy, small hail is possible vertical wind shear is small form in very weak shear environments with new storms forming in an unorganized manner can be severe at dissipation

Hurricane Characteristics

sustained winds of 120km or more seal level pressure less than 990 mb varying sizes but cloud shield usually more than 400 km diameter warm tropical waters more than 27C (~80)

Levels of storm

varys worldwide

Tornado formation

western winds at high levels bring cool, moist air from pacific southwesterly winds at mid-levels bring hot, dry air from mexico deserts southerly winds at surface bring warm, humid air from Gulf of Mexico

Wind variability

wind direction varies more then 60 degrees and speed is more than 6 knots

Severe thunderstorm

winds stronger than 58 mph hailstones larger than 0.75in tornado

Types of lightning

within cloud cloud-to-cloud cloud-to-air cloud-to-ground negative positive lightning (~10%)