IMS 10 - Hurricane

Hurricane

Tropical Cyclone

·         Warm-core, low press system with organized circulation @ sub/tropical waters

Classification

·         Wind speed

·         < 38mph/60kmph = tropical depression

·         > 39mph/60kmph = tropical storm; given names

·         > 74mph/120kmph = hurricane

Hurricane Intensity (Saffir-Simpson Scale

Category	Wind Speed (km/h)	Damage
1	120-153	Minimal
2	154-177	Moderate
3	178-209	Extensive
4	210-249	Extreme
5	>250	Catastrophic

Hurricanes – N S America (Official season Jun 1 – Nov 20; mid-Sep peak)

Typhoons – Western North Pacific Ocean (dangerous winds, torrential rain flood, property damage, life loss)

Cyclones – Indian Ocean

Formation

·         From simple thunderstorms; grow to cyclone strength by ocean & atmosphere

·         Ocean must > 26.5 °C / 81 °F (heat + moisture/humidity = cyclone energy source)

·         Humidity reduce cloud evaporation, maximises latent heat qty

·         Weaken rapidly if travel cold land/ocean

Vertical wind shear

·         Amount of wind direction/speed change with increasing altitude

·         Weak wind shear; storms grow vertically; condensation latent heat released above storm

·         Strong wind shear; storm slanted; latent heat dispersed over larger area

Hurricane Parts

·         Centre/eye (13-16km) relatively calm

·         Eye wall most violent (Most air propelled out @ top; raise upward motion)

·         Remain in tropics; if move over land energy cuts off

·         Trade winds drive hurricanes; East to West across ocean

·         Diameter 200km – 800km

·         Affected by Coriolis Effect

Typhoon

·         Tropical storm Dianmu – North Western Pacific

·         Hurricane Celia – Eastern Pacific

·         Tropical Storm Estelle – Eastern Pacific

·         Depression Colin – Atlantic

National Hurricane Centre

·         (1979) List alternate between male & female; alphabetically & chronologically

·         First tropical storm of the year begins with A – W (not Q or U)

·         6 rotating list; name retired by more devastating hurricane

Function

·         Transfer ocean heat to upper atmosphere and blown to poles by high winds

·         Keep Polar Regions from cooling & tropics from overheating

·         Tropical cyclone regulate the earth temperature

·         Disrupt cyclone intensity; ocean retains heat.

·         Heat build-up enhances successive storm; increase frequency & intensity.

Southwest monsoon (May – Oct)

Malaysia Monsoon

·         Heating land & sea

·         Summer – Land heats rapidly (SW Monsoon)

·         Winter – Land cools rapidly (NE Monsoon)