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Understanding Thunderstorms: Formation, Characteristics, and Severe Storm Impacts

This comprehensive overview delves into the fascinating world of thunderstorms, exploring their characteristics, occurrence, and conditions necessary for their formation. Key topics include the structure of cumulonimbus clouds, stages of development from cumulus to mature to dissipation, and the dynamics of severe thunderstorms that can produce damaging winds, hail, and tornadoes. Additionally, we discuss lightning as an underappreciated hazard, including the electrical charge dynamics that create it. By understanding these elements, we enhance our preparedness for nature’s powerful storms.

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Understanding Thunderstorms: Formation, Characteristics, and Severe Storm Impacts

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Presentation Transcript

  1. GEOL 1301 – Thunderstorms and Lightning

  2. Characteristics Occurrence Conditions for Formation Stages of Development Severe Thunderstorms Lightning Thunderstorms

  3. Characteristics • Cumulonimbus cloud with lightning and thunder

  4. Characteristics • Cumulonimbus cloud with lightning and thunder • Heavy rain and gusty winds

  5. Dry Thunderstorms with Virga

  6. Structure of a Thunderstorm

  7. High Winds – Gust Front

  8. Characteristics • Cumulonimbus cloud with lightning and thunder • Heavy rain and gusty winds • Some storms – hail and tornadoes

  9. Hail

  10. World Record - Aurora, NE June 20037” diameter (volleyball size) and 1.7 lbs. Storm > 70,000 ft. high

  11. Characteristics • Cumulonimbus cloud with lightning and thunder • Heavy rain and gusty winds • Some storms – hail and tornadoes • Individual thunderstorm cells • Av. 15 mi. (25 km) diameter • Last 30 minutes • Multicell clusters very common

  12. Multicell ClusterDowndraft from one cell forms another

  13. 100,000+ Thunderstorms in U.S. Each Year

  14. Conditions for Formation • Daily heating – air mass thunderstorm

  15. Conditions for Formation • Daily heating – air mass thunderstorms • Frontal boundary (primarily cold, stationary or occluded) - may form a squall line

  16. Squall Line

  17. In Advance of Cold Front

  18. Conditions for Formation • Daily heating • Frontal boundary • Dryline

  19. Dryline

  20. Conditions for Formation • Daily heating • Frontal boundary • Dryline • Sea breeze convergence

  21. Sea Breeze Convergence

  22. Conditions for Formation • Daily heating • Frontal boundary • Dryline • Sea breeze convergence • Outflow boundary

  23. Outflow Boundaries from Large Storms

  24. Stages in Development Cumulus Mature Dissipative

  25. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr)

  26. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr) • Hail > 1” (2.5 cm) diameter (quarter size)

  27. HailstreakWest Texas Severe Thunderstorm

  28. Large Hail

  29. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr) • Hail > 1” (2.5 cm) diameter • Tornado

  30. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr) • Hail > 1” (2.5 cm) diameter • Tornado • Common features: anvil top

  31. Anvil Top

  32. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr) • Hail > ¾” (1.9 cm) diameter • Tornado • Common features: anvil top, frequent lightning

  33. Severe Thunderstorms • Characteristics - any or all: • Wind gusts > 58 mph (93 km/hr) • Hail > ¾” (1.9 cm) diameter • Tornado • Common features: anvil top, frequent lightning, and mammatus clouds

  34. Mammatus Clouds

  35. Most Dangerous Severe Thunderstorms • Supercells

  36. Supercell Thunderstorm - Eastern Colorado

  37. Training Effect Can Produce Flooding

  38. Most Dangerous Storms • Supercells • Mesoscale convective systems (MCS’s)

  39. LightningAn Underestimated Hazard

  40. Central Texas – 8 to 12 strikes/ mi2 / year

  41. 80% of Lightning is Cloud-to-Cloud

  42. Lighting Development • Large electrical charge imbalance

  43. Lighting Development • Large electrical charge imbalance • Within the storm

  44. Lighting Development • Large electrical charge imbalance • Within the storm • Between storm and ground

  45. Lighting Development • Large electrical charge imbalance • Within the storm • Between storm and ground • Collision - droplets and ice crystals • Ice crystals +

  46. Lighting Development • Large electrical charge imbalance • Within the storm • Between storm and ground • Collision - droplets and ice crystals • Ice crystals + • Water droplets –

  47. + Charge Induced Below Thunderstorm

  48. Stepped Leader of Ionized Air Branches Downward

  49. Spark Jumps from Tall Object to Stepped Leader

  50. Flowing + Charges Create Return Stroke

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