Knowledge Organiser: Weather Hazards

Tropical storm: Intense rotating low-pressure system over warm tropical ocean (≥26°C); called hurricane (Atlantic), typhoon (Pacific), or cyclone (Indian Ocean)
Storm surge: Dome of ocean water pushed onshore; typically the deadliest component of a tropical storm
Coriolis effect: Earth's rotation deflects moving air — right in NH (anticlockwise storms), left in SH (clockwise storms); zero at equator
Eye: Calm, cloudless centre with lowest pressure; 20–65 km diameter; sinking air suppresses clouds
Eyewall: Ring of most intense winds and rainfall surrounding the eye
Latent heat: Energy released when water vapour condenses — the positive feedback that drives storm intensification
Managed retreat: Allowing rivers to flood naturally; reduces maintenance cost but conflicts with farming and habitation
Rhynes: Drainage channels on the Somerset Levels; when blocked by sediment, flood risk increases

8 November 2013: Typhoon Haiyan landfall, Philippines
195 mph (315 km/h): Haiyan wind speed — strongest landfalling storm ever recorded
7.5 m: Storm surge height in Tacloban — primary cause of deaths
6,300+: Deaths from Haiyan; 4.1 million displaced
$12 billion: Economic damage from Haiyan
26°C: Minimum ocean surface temperature for tropical storm formation
5°–20°: Latitude band where tropical storms form
Winter 2013–14: Wettest winter in England and Wales for 250 years
17,000 acres: Flooded on Somerset Levels; 600+ homes
200%: Of average rainfall received in Somerset, January 2014
£100 million: Somerset Flood Action Plan cost

Philippines: Western Pacific typhoon belt; among world's most typhoon-prone nations
Tacloban, Leyte: City destroyed by Haiyan surge; 80% of structures damaged or destroyed
Somerset Levels, SW England: Flooded winter 2013–14; drainage managed since medieval times
Rivers Tone and Parrett: Main drainage rivers of Somerset Levels; un-dredged 1990s–2014
Muchelney and Thorney: Villages isolated for weeks during Somerset flooding
Western Pacific Ocean: World's most active tropical storm basin

Tropical storms CANNOT form at the equator — Coriolis effect = 0 there
Storm surge kills more people than wind — always specify this in answers
NH storms rotate anticlockwise; SH storms clockwise (Coriolis deflects right in NH, left in SH)
Storms form over warm water (≥26°C); weaken over land or cool water
Three risk-reduction approaches: monitoring/prediction, planning, protection
LICs have higher death tolls due to structural vulnerability: housing, evacuation, awareness, wealth
Somerset: record rainfall + saturated ground + un-dredged rivers + low-lying topography = severe flooding
Post-Haiyan: Philippines now separates surge warnings from wind warnings — direct lesson from 2013
Mangroves can reduce surge wave energy by 50–70% — natural coastal protection
Climate change → warmer oceans → more intense storms; rapid intensification becoming more common

Saying wind kills most people in tropical storms: Storm surge is the deadliest component — always specify this; Haiyan's 7.5 m surge in Tacloban caused the majority of the 6,300+ deaths
Forgetting the Coriolis effect rule: Tropical storms cannot form at the equator because the Coriolis effect is zero there — this is a frequent 2-mark question
Generic LIC/HIC comparison without evidence: Don't just say "LICs suffer more" — use specific figures: Philippines (LIC, 6,300 deaths from Haiyan) vs Somerset (HIC, 0 deaths from 2013–14 flooding)
Mixing up mitigation and management strategies: Prediction/monitoring, planning (land use zoning) and protection (flood defences) are three distinct approaches — name which category your example belongs to

D — Dredging not done since early 1990s — river capacity reduced by 20+ years of sediment accumulation
R — Record rainfall — 200% of average in January 2014; wettest winter in 250 years
I — Inundation of 17,000 acres; 600+ homes; villages isolated for weeks by road
P — Policy debate — managed retreat (Environment Agency) vs active dredging (local communities); Somerset Flood Action Plan (£100m) introduced as resolution
S — Saturated ground from autumn 2013 storms — no infiltration capacity left when winter rains arrived
Primary = P for Punch — the storm's direct physical punch: wind damage, surge flooding, rainfall flooding. Happens during the event. Affects everyone equally regardless of wealth.
Secondary = S for Slow Burn — consequences that develop slowly after the storm passes: disease, displacement, economic disruption, psychological trauma. Shaped heavily by vulnerability — how quickly society can restore water, provide shelter, fund reconstruction.

Weather Hazards, Knowledge Organiser