History UsefulNotes / Tornadoes

** '''The Bridge Creek-Moore, Oklahoma Tornado''', May 3, 1999. Wind speeds of up to 318 mph were recorded by mobile Doppler radar units - the fastest wind speed recorded on Earth, incidentally.

** '''Oklahoma City, Oklahoma, US'''. Counting the metro area ''and'' the suburbs such as Bridge Creek and Moore, the Oklahoma City region has been hit by at least five significant tornadoes.
** '''Tanner, Alabama, US''' holds the record out of Tornado Alley proper - it was hit by three [=F5/EF5=] tornadoes, two within 30 minutes in the 1974 Super Outbreak and one in the 2011 Super Outbreak.

*** '''The Tri-State Tornado''', March 18, 1925. 695 people were killed by this tornado, whose path ran through Missouri, Illinois, and Indiana. The Illinois phase was responsible for record fatalities in a single city (234 in Murphysboro) and a single school (33 at the De Soto School in De Soto).

** Speaking in the absolute most generality, a tornado is born of the horizontal rotation that begins when a cold, dry air mass slides underneath a warm, moist air mass. Think of it as an extreme case of thermal convection: When a liquid or gas receives heat, its matter will move faster due to the increased activity of its atoms and molecules; eventually, the hot mass will be in contact with cold or warm mass and the transfer of UsefulNotes/{{Energy}} between the two will make the whole material system much more active thermally and mechanically. In the case of a forming tornado, the increase of temperature will make dry air less dense, so its hotter mass will experience an updraft which, due to the abrupt increase in speed and direction, will begin to rotate and form a jet stream that feeds the moist air; the latter's water droplets form what we know as the funnel cloud, which grows in size and strength until the funnel proper descends from the cloud. when it touches the ground, the tornado is born.

* '''Tornado Outbreak:''' An event where a single storm system spawns multiple tornadoes.