Severe Weather Flashcards
Cumulus Stage
The initial phase of a thunderstorm where warm, moist air rises, cools, and condenses into a cumulus cloud. Dominated by updrafts; no precipitation yet
Entrainment
The process where dry air from outside the cloud mixes into the storm, enhancing downdrafts by cooling and evaporating some moisture
Mature Stage
The most intense phase of a thunderstorm where strong updrafts and downdrafts coexist. Heavy rain, lightning, and sometimes hail occur
Cell
A single convective updraft and downdraft pair within a thunderstorm system. Thunderstorms can have one or multiple cells
Anvil
The flat, spreading top of a cumulonimbus clodu formed when rising air reaches the tropopause and spreads outward
Dissipating Stage
Final stage of a thunderstorm when downdrafts dominate and cut off the supply of rising warm, moist air, causing the storm to weaken
Air Mass Thunderstorm (Ordinary Thunderstorm)
Isolated, short-lived storms fueled by surface heating. Typically form away from fronts or organizes weather systems
Outflow Boundaries (Gust Fronts)
The leading edge of cool air rushing down and outward from a storm; can trigger new thunderstorms
Squall Lines
Long, organized lines of thunderstorms often ahead of cold fronts, producing strong winds, heavy rain, and sometimes tornadoes
Lightning
A sudden electrostatic discharge between oppositely charged regions in a cloud (or between cloud and ground) that restores electrical balance
Graupel
Soft, small pellets formed when supercooled water droplets freeze onto falling snowflakes; involved in electrical charge separation for lightning
Stepped Leader
The inital channel of ionized air that descends from a thunderstorm, creating a path for lightning
Thunder
The sound caused by the rapid expansion of air surrounding a lightning bolt due to extreme heat
Dry Thunderstorms
Thunderstorms that produce lightning and strong winds but little to no rain at the surface; major cause of wildfires
Flash Floods
Sudden, intense floods caused by heavy rainfall over a short period, often in areas with poor drainage or steep terrain
Downbursts
Strong downdrafts that hit the ground and spread outward, producing damaging straight-line winds
Microbursts
Small, very intense downbursts affecting areas less than 2.5 miles wide; extremely dangerous to aircraft
Tornado Alley
A region in the central United States (like Texas, Oklahoma, Kansas, Nebraska) with a high frequency of tornadoes due to ideal atmospheric conditions
Funnel Cloud
A rotating funnel-shaped cloud extending from a thunderstorm but not touching the ground (yet); may become a tornado if it reaches the ground
Fujita Intensity Scale
The original scale created by Dr. Ted Fujita in the 1960s to classify tornadoes based on the damage they cause, ranging from F0 to F5
Enhanced Fujita Scale
The updated version (since 2007) that more accurately relates observed damage to estimated wind speeds, using 28 different damage indicators. Ranges from EF0 to EF5
Suction Vortices
Small, intense whirls within a larger tornado; can cause especially extreme damage locally
Multiple Vortex Tornadoes
Tornadoes that contain two or more small, rotating vortices inside the main circulation; often more destructive
Tornado Watch
Issued when conditions are favorable for tornadoes to form. Means “Be alert”
Tornado Warning
Issued when a tornado has been spotted or indicated by radar. Means “Take immediate shelter)
Doppler Radar
A radar system that detects motion within storms by measuring the frequency change of returned signals. Helps identify rotation (possible tornadoes)
Lightning Formation
Charge separation inside clouds creates an electric field –> discharge as lightning when the electric field becomes strong enough
