Natural Disasters Ch. 10

air-mass thunderstorm

local, short-lived thunderstorm that may form & dissipate in several hours

blizzard

strong, cold winds filled with snow

bomb cyclone

generally a non-tropical storm that rapidly intensifies as barometric pressure drops 24 or more millibars in 24hrs

barometer

an instrument for measuring atmospheric pressure

cumulonimbus

a dense, towering, vertical cloud up to 20km (12mi) high. it’s the final stage of growth of cumulus

cumulus

a tall, puffy cloud made of rounded masses stacked upon each other, generally with a flat base & heigh <1km (0.6mi)

derecho

winds that blow straight ahead

downburst

a localized, severe downdraft of air that includes an outburst of strong winds on the ground

fetch

the length of water surface the wind blows across to create waves or lake-effect snow

freezing rain

supercooled rain that turns to ice when it touches objects such as trees & powerlines

hail

precipitation of hard, semispherical pellets of ice

hook echo

a band of heavy rain & hail in rotation around a supercell thunderstorm. usually recognized by radar

hyperthermia

overheating of the body, commonly due to extreme weather. body temperature greater than 40 degrees celsius (104 degrees fahrenheit) can be life threatening

hypothermia

occurs when body temperature drops below 35 degrees celsius (95 degrees fahrenheit) & the heart, respiratory, and other systems cannot function normally

lake-effect snow

snow produced after cold air blows over large areas of warmer water, picking up water vapor that forms clouds that precipitate snow just past the downwind shoreline

lightning

a flashing of light as atmospheric electricity flows between clouds or between clouds and the ground

mesocyclone

a rotating mid-level region within a supercell thunderstorm

nor’easter

a winter weather condition involving a low-pressure system with its center offshore of the Atlantic coasts of the US & Canada. the counterclockwise rotation brings warm, moist offshore air into contact with cold Arctic air

severe thunderstorm

thunderstorm with winds faster than 58mph; it can produce large hail & tornadoes

single-cell thunderstorm

a single thunderstorm with one main updraft, they pass through their life cycle of development, maturity, & decay with a few hours

sleet

precipitation of fine icy particles formed as frozen rain

supercell thunderstorm

a complex thunderstorm formed from a huge updraft. commonly is tilted, allowing rain, hail, & tornadoes to exist side-by-side

thunder

the sound given off by rapidly expanding gases along the path of a lightning discharge

thunderstorm

a tall, buoyant cloud of moist air that generates lightning & thunder, usually accompanied by rain, gusty winds, & sometimes hail

tornado

spinning funnels of wind whose rotating wind speeds can exceed 480km/hr *300mph)

tornado outbreak

6 or more tornadoes within 24hrs from a single weather system

tornado warning

an alert from the National Weather System that a tornado is occurring or is imminent

vortex

a whirling body of water or air with circular rotation around an axis that may be oriented vertically, horizontally, or somewhere in between

wall cloud

a markedly lower cloud that may form in the area of strongest updraft in a supercell thunderstorm. many strong tornadoes form within wall clouds