Thunderstorms and Tornados: Formation, Characteristics, and Impacts, Slides of Geology

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Thunderstorm Formation

• Ingredients
  • warm, moist air (often mT)
  • unstable (or conditionally unstable if lifting mech.)
  • encouraged by diverging air aloft

The Geography of Thunderstorms

Violent Associations

• Hail
• Downbursts (Microbursts)
• Lightning and thunder
• Tornadoes

Hail

• Formation
  • Layer upon layer of ice and water in high speed thunderstorm cloud convection cycle
• Largest diameter officially measured: 8. inches (20 cm) diameter, Vivian, South Dakota, July 23, 2010
• Damage to crops; fatalities.

Lightning

• discharge of electricity that occurs in mature thunderstorms
• Cause: charge separation in cloud sets up electrical potential - Role of lightning is to equalize these differences in electrical potential. - Important fixer of Nitrogen.

Frequency of Occurrence

Globally, lightning flashes ± 100 times per second.

USA: Real-time Lightning

http://www.intellicast.com/Storm/Severe/Lightning.aspx Docsity.com

Thunder

• Air poor conductor of electricity
• Huge electrical potential develops
• Lightning bolt ‘superheats’ the air (30,000°C, 54,000 °F)
• Surrounding air expands violently ⇒ sound wave

Key Points

• Thunderstorm formation and life cycle
• Thunderstorm geography and frequency
• Violent associations
  • hail, downbursts, lightning/thunder
  • next lecture….tornadoes

Tornadoes

Tornado Clip