Unit 9 - Essays - Atmospheric Disturbances Flashcards
(4 cards)
‘Flooding is the most significant hazard from large-scale atmospheric disturbances.’ How far do you agree?
‘Flooding is the most significant hazard from large-scale atmospheric disturbances.’ How far do you agree?
Paragraph 1 – Flooding from Storm Surge
Nargis: 3.5 m surge drowned villages; 138,000+ deaths; low delta + no warning.
Katrina: 8.5 m surge; levee failure flooded 80% of New Orleans; most deaths caused by water.
Haiyan: 5–6 m surge + high tide caused mass death in Tacloban.
Paragraph 2 – Flooding from Rainfall
Haiyan & Nargis: Intense rainfall flooded coastal/inland areas; caused landslides and delayed aid.
Katrina: Rainfall added to storm surge; poor drainage overwhelmed levees.
Paragraph 3 – Winds as Significant Hazard
Haiyan: 310 km/h winds flattened entire towns.
Katrina: 280 km/h winds damaged power, structures.
Nargis: 215 km/h winds destroyed housing; contributed to overall damage.
Paragraph 4 – Other Hazards (Mass Movement, Disease)
Haiyan: Landslides in Leyte/Samar worsened rescue delays.
Nargis: Waterborne diseases like cholera; saltwater ruined farmland.
Katrina: Infrastructure collapse and social displacement caused long-term suffering.
Paragraph 5 – Variation by Location and Governance
Nargis: Flooding deadliest due to low land + lack of warning.
Katrina: Wind less deadly due to stronger buildings; flood effects from levee failure.
Haiyan: Wind and storm surge jointly caused devastation.
Conclusion
Judgement: Agree to a large extent – flooding (from surge or rain) is usually most fatal, especially where land is low-lying and evacuation fails. However, winds and mass movement can be equally destructive where vulnerability exists (e.g. Haiyan).
Assess the extent to which high winds are the most significant hazard of small-scale atmospheric disturbances (tornadoes).
Assess the extent to which high winds are the most significant hazard of small-scale atmospheric disturbances (tornadoes).
Paragraph 1 – High Winds as Primary Hazard
1974: 300+ km/h winds; F5 tornadoes destroyed homes, towns (e.g. Xenia, OH).
Henryville 2012: EF4 tornado (280 km/h) destroyed schools, homes.
Most deaths/injuries due to high-speed debris and structural collapse.
Paragraph 2 – Intense Precipitation & Flooding
1974: Golf ball-sized hail and flash floods caused property damage.
Henryville: Hail, heavy rainfall caused road washouts – secondary but less deadly.
Paragraph 3 – Flying Debris & Pressure Drop Effects
Both events: Debris a major cause of death and injury.
Rapid pressure drops caused internal building damage – sudden implosion effect.
Paragraph 4 – Psychological and Community Impacts
Henryville: School destruction disrupted education; long-term trauma.
1974: Communities never fully recovered; no mental health support.
Paragraph 5 – Variation in Impact due to Preparedness
1974: Few warnings, high fatalities.
2012: Better prediction, fewer deaths despite strong winds.
Conclusion
Judgement: Strongly agree – high winds are the defining and most dangerous hazard of tornadoes, causing direct destruction and death. Other hazards (flooding, debris) amplify impacts but are secondary.
‘Sea temperature is the most important factor influencing the formation and development of large-scale atmospheric disturbances.’ Assess this view.
‘Sea temperature is the most important factor influencing the formation and development of large-scale atmospheric disturbances.’ Assess this view.
Paragraph 1 – Importance of Sea Surface Temperatures (SSTs)
All three cases: SSTs > 28°C (Nargis, Katrina, Haiyan) allowed cyclone formation.
Haiyan/Katrina: Deep warm waters (30–31°C) triggered rapid intensification.
Paragraph 2 – Role of Wind Shear
Haiyan: Exceptionally low wind shear helped maintain Category 5 status.
Katrina: Low shear allowed symmetrical development and intensification.
Paragraph 3 – Coriolis Effect (Latitude)
Cyclones require Coriolis force – formed between 6–23°N (Haiyan 6–8°, Katrina 23°).
Without this, storms cannot rotate or form.
Paragraph 4 – Pre-existing Low Pressure & Surface Triggers
All storms began as tropical waves or lows.
Pre-existing instability and moisture helped initiate convection (e.g., Nargis in Bay of Bengal).
Paragraph 5 – Regional Geography
Katrina: Gulf Loop Current fueled intensification.
Haiyan: Narrow Leyte Gulf funneled surge.
Nargis: Irrawaddy Delta made storm surge deadlier.
Conclusion
Judgement: SSTs are necessary but not sufficient – they provide energy, but wind shear, Coriolis force, and geography all play critical roles in cyclone development. Best viewed as a multi-factor process.
Assess the relative importance of the factors influencing the formation of tornadoes.
Assess the relative importance of the factors influencing the formation of tornadoes.
Paragraph 1 – Temperature & Pressure Gradients
1974 & Henryville: Clash of warm Gulf air and cold Canadian air created steep instability.
Warm air uplift was critical to thunderstorm formation.
Paragraph 2 – Moisture and Humidity
Both events: Gulf moisture led to high dew points, enhancing convection.
Latent heat from condensation fed storm development.
Paragraph 3 – Wind Shear
1974: Strong speed + directional shear = mesocyclones → multiple tornadoes.
Henryville: Adequate shear for EF4 tornado; sustained storm rotation.
Paragraph 4 – Jet Stream & Upper-Level Divergence
1974: Powerful polar jet enabled large-scale divergence and uplift.
Henryville: Subtropical jet played a smaller but supportive role.
Paragraph 5 – Surface Triggers (Cold Fronts)
Both events: Cold fronts + low pressure provided strong lift mechanisms.
Triggered explosive storm development over unstable regions.
Conclusion
Judgement: No single factor is dominant – tornadoes form when multiple elements align (instability, moisture, shear, and triggers). Temperature gradients and wind shear are most critical in sustaining supercells that generate tornadoes.
