Cyclones, Thunderstorms, Tornadoes

Flashcards covering key terms and concepts about cyclones, thunderstorms, and tornadoes.

Mid-latitude cyclones

A storm system formed by the meeting of warm and cold air masses along the polar front, creating a low-pressure point.

Tropical cyclones

Intense wind and rain storms that develop over oceans in the tropics, driven by abnormal heat accumulation in tropical waters.

Cyclogenesis step 1

- cold polar air moving south meets warmer tropical air moving north creating a stationary front boundary
- point of low pressure is created along boundary forming a draft

cyclogenesis step 2

- becomes an occluded system: closing the funnel
- turns a stable stationary front into a kirk/bend marking the start of cyclonic circulation

Occluded system

A state in cyclogenesis where a stationary front evolves into a cyclonic circulation due to the closing of the funnel.

Comma head

The part of a weather system represented by a comma shape, bringing snow, hail, and sleet.

Comma tail

The part of a weather system that brings storm surges and thunderstorms.

Thunderstorm formation

Occurs when warm, humid air rises, leading to warm updrafts until downdrafts dominate.

Single-cell thunderstorm

A type of storm where warm, moist air rises vertically, causing precipitation as it cools.

Supercell thunderstorm

- involves shear
- differential of speed between the surface winds and the altitude winds
- can cause tornadoes (funnel)

Updrafts

Air currents that rise up to high altitudes, where moisture condenses and precipitates.

base diameter of a tornado

50 m to 1 km

Tornado wind speed

Ranges from 100-320 km/h.

Tornado forward speed

Ranges from 0-110 km/h.

Tornado danger location

Central North America,
- flat land

- warm moist Gulf air

- cold dry northern air

- strong westerlies

Tornado safety protocol

move to a basement/interior room - protect your head - do not find shelter under highway overpasses (wind speed can be amplified) - cars only provide modest protection

1991 Kansas F5 tornado

146 people evacuated (no deaths/injuries) - 149 people entered community shelter (no deaths/injuries) - 38 stayed at home (13 deaths, 17 hospitalized)

Hook echo

the shape of a hook on a Doppler radar screen that indicates the possible presence of a tornado

Tornado Alley

Regions of the US where the convergence of 3 major wind types creates favorable conditions for tornadoes.

Temporal frequency of tornadoes

Periods of the year, particularly spring and summer, when tornado occurrences are most likely.

Fujita scale

A scale used to categorize tornadoes based on the damage they inflict.

Tornado classification factors

Historically based on damage rather than wind speed, as anemometers are seldom available in tornadoes.

EF0

Tornado classification for wind speeds of 65-85 mph, resulting in minor damage.

EF1

Tornado classification for wind speeds of 86-110 mph, resulting in moderate damage.

EF2

Tornado classification for wind speeds of 111-135 mph, resulting in considerable damage.

EF3

Tornado classification for wind speeds of 136-165 mph, resulting in severe damage.

EF4

Tornado classification for wind speeds of 166-200 mph, resulting in extreme damage.

EF5

Tornado classification for wind speeds above 200 mph, resulting in catastrophic damage.

Flamborough EF-1 tornado

tornado lasted 30s - 700m long x 100m wide - rural area so lots of wood debris - harvest destroyed - nearby houses not affected

Tornado fatalities

Over 60 deaths occur annually, primarily from flying debris.

2007 Greensburg tornado

An EF5 tornado that destroyed 95% of Greensburg, resulting in 11-12 fatalities.
63 injured
tornado emergency was issued 10-12 mins before impact

2011 Joplin tornado

A tornado of fluctuating intensity (EF1-EF5) causing 158 fatalities and over 1000 injuries.