Tornado Formation and Tornado Alley

• Each year, the U.S. experiences over 1,200 tornadoes.
• A tornado is a violently rotating column of air formed during thunderstorms, with winds up to 250 mph.
• The word "tornado" comes from the Spanish word "tornar," meaning "to turn."
• Tornadoes are also known as twisters, cyclones, or funnel clouds.
• They are most common in southern Canada and "Tornado Alley" in the U.S.
• Tornado Alley includes: South Dakota, Nebraska, Kansas, Oklahoma, northern Texas, and eastern Colorado.
• The Great Plains and Florida are prone to tornadoes due to frequent thunderstorms.

Formation

• Tornadoes typically form in late spring and summer.
• This relates to conditions ideal for supercell formation and updrafts of hot air.
• A supercell is a large thunderstorm with rotating winds, forming in approximately 1 out of 1,000 storms.
• When a supercell forms, it produces a tornado about 20% of the time.
• Vertical wind shear during severe thunderstorms and supercell formation creates a horizontally rotating air column.
• Updrafts lift this column, causing it to narrow and spin faster, forming a funnel cloud.
• A funnel cloud becomes a tornado only when it touches both the ground and the source cloud.
• Doppler radar detects hook echoes indicative of a supercell, providing about 10 minutes of warning.
• A hook echo is a bend in the radar signal for a thunderstorm.
• The rapid formation and movement of tornadoes makes it difficult to accurately predict their development.

Effects

• Tornadoes can be over 660 feet wide and travel less than six miles.
• Tornadoes cause an estimated $400 million in damage annually.
• Around 70 people die each year due to tornadoes.
• Tornadoes damage the environment by destroying forests and habitats.
• Wind-damaged forests are more susceptible to non-native plant species.

Categorization

• Meteorologists use Doppler radar and computer modeling to predict tornadic activity.
• Hook echoes indicate areas of rotation within a thunderstorm.
• Stormchasers use equipment and weather balloons to measure tornado formation factors.
• The National Weather Service assesses damage to determine wind speed and path.
• Tornadoes are rated using the Enhanced Fujita Scale, developed by Ted Fujita.
• The Enhanced Fujita Scale evaluates damage to buildings and trees against 28 damage indicators.
• Tornado size and path length are positively correlated with its destruction level.

Enhanced Fujita (EF) Scale

• Before 2007, the Fujita-Pearson (FPP) scale was used, based on damage types.
• The EF Scale, introduced in 2007, incorporates damage indicators and degrees of damage.
• The EF Scale reflects the wind speeds associated with a tornado.
• EF0: 65-85 mph, broken tree branches, some shingles blown from roofs
• EF1: 86-110 mph, loss of exterior doors, many shingles lost
• EF2: 111-135 mph, roofs torn off, mobile homes destroyed
• EF3: 136-165 mph, severe damage to large buildings; trains and cars overturned
• EF4: 166-199 mph, whole houses leveled
• EF5: 200-230 mph, houses swept away

Explore tornado formation, causes, and impact, focusing on Tornado Alley. Tornadoes are violently rotating columns of air that form during thunderstorms, with winds reaching speeds of up to 250 mph. The Great Plains and Florida are highly susceptible to tornadoes due to frequent thunderstorms.