Hazards: 5.4 - Storm Hazards Flashcards
Define Tropical revolving storms (hurricanes)
Intense low-Pa weather systems that develop in the tropics
What must the diameter be for tropical revolving storm classification?
200-700 km
Outline how tropical revolving storms initially form
Low Pa area warm air spirals together - small-scale disturbances enlarge into tropical storms
Outline the 1st factor of hurricane development (location)
Oceanic location - temp >27 C to maintain rising air currents
Outline the 2nd factor of hurricane development (ocean)
Ocean depth at least 70m - moisture for rapidly rising air which cools and condenses releasing latent heat energy for fuel
Outline the 3rd factor of hurricane development (equator)
5 degrees N/S of equator so Coriolis ‘spinning’ effect = MAX air rotation
Outline the 4th factor of hurricane development (low)
Low-level air convergence in lower atmospheric circulation system
Outline the 5th factor of hurricane development (top)
Rapid air outflow in upper atmospheric circulation - push away warm air
Outline the central eye of a tropical storm
Develops once storm matures
10-50km in diameter, calm conditions, clear skies, higher temperatures & descending air
Outline the eye wall of the tropical storm
Most powerful part of the storm
Bank of cloud that rings the central eye with heavy rains and winds
Outline the tornadoes of the tropical storm
Clouds & rain beyond eye wall form waves leading to tornadoes
Hard to predict and destructive
Outline the relationship between tropical storms and land
Storms get weaker when going inland & vice versa
What direction do tropical storms typically move?
Westwards
What are tropical storms known as in the Caribbean Sea? What’s their % of all tropical storms
Known as hurricanes
11% of all storms
What % do tropical storms do ones in the east Pacific/western side of central America make up?
17% of all storms
What are tropical storms known as in the Arabian Sea/Bay of Bengal? What’s there % out of all tropical storms?
Known as cyclones
8% of all storms
What are tropical storms known as off southeast Asia? What’s their % out of all tropical storms?
Known as typhoons
1/3 of all storms
What is the % tropical storms in off Madagascar/southeast Africa have out of all tropical storms?
11% of all storms
What are tropical storms known as in western Australia/southwestern Pacific? What’s their % out of all tropical storms?
Known as willy-willies
20% of all storms
Outline how the magnitude of tropical revolving storms are measured
Measured with the Saffir-Simpson scale
Has 4 scales based on central pressure, wind speed, storm surge and damage potential
Outline the 4 measurements for the Saffir-Simpson scale
Central pressure - 920mb or >
Wind speed - 250 km/h or <
Storm surge at 5.5m or <
Damage potential - complete roof failure of all structures 3m above sea level
Outline the average lifespan of a tropical storm
7-14 days
Outline the annual frequency of tropical storms developing and outline how many become tropical revolving storms
80-100 Tropical Storms develop
Approximately 80% will intensify to become tropical revolving storms
Define storm surges
Surge of high water typically about 3cm height that sweeps inland
