Storm hazards Flashcards
Outline the distribution of Hurricanes
North Atlantic (Caribbean sea and Gulf of Mexico) (11% of tropical storms) and NE Pacific (western side of central America) (17% of tropical storms)
Distribution of storms in general
Tropical maritime areas between 5-20N/S but not on the equator.
Outline teh distribution of cyclones
South Pacific/Indian - Arabian sea and Bay of Bengal (8% of tropical storms). Off of Madagascar (southeast Africa) 11%
Outline the distribution of Typhoons
Northwest Pacific (off of southeast asia) 33%.
Outline the distribution of Willy Willies
Off north-western and north-eastern Australia (20%)
Give five conditions needed for the formation of a tropical storm
Warm ocean above 27C to at least 70m below the surface
continuous source of heat in order to maintain rising air currents and allow for latent heat to be released by condensation powering the storm. And less frictional drag over the ocean
At least 5-20N/S [1] of the equator so coriolis force can bring about the maximum rotation to the area.
Low level convergence of air [1] forces warm air to rise
Why do tropical storms decay upon reaching land?
Lose source of heat and moisture which provides latent heat when evaporatingIncreased frictional drag with the land surface slows down the storm
In what direction do tropical storms spin in the northan hemisphere?
anticlockwise
In what direction do tropical storms spin in the southern hemisphere
clockwise
What are the four stages of tropical storm formation?
Tropical Disturbance winds less than 23mph
Tropical depression 23-39mph
Tropical storm [1] 39-73 mph
Hurricane: 74 mph +
What scale is used to measure the magnitude of tropical storms?
Saffir Simpson scale
What four factors are measured by this scale?
Central pressure
Wind speed
Storm surge
Damage potential
Describe the frequency of tropical storms in the northan hemisphere
June - November
Describe the frequency of tropical storms Southern hemisphere
November - April
Describe the regularity of tropical storms.
Irregular - occur in same areas but no clear spatial or temporal pattern.
Describe the predictability of tropical storms.
Fairly predictably with use of satellite tracking of cloud formations etc.
What are the three primary hazards of tropical storms?
Strong winds
Heavy rainfall
Storm surges
Give two secondary hazards of tropical storms.
FloodingLandslides
Outline the formation of tropical storms.
In the tropics, solar radiation warms the ocean to 27 degrees. The ITCZ is usually overhead.Warm moist air rises through the air in thermals. This creates an area of low pressure at the centre of the storm.As rising air cools > condensation > cumulonimbus clouds and heavy rainfall. The latent heat given off when the air cools powers the tropical storms.The coriolis effect causes rising air to spin upwards around a central eye (75 mph).Air rushes in from areas of higher pressure outside the storm to replace the rising air - creating strong winds. Cold air sinks in the eye of the storm > no cloud, drier and calm.Tropical storms are carried across the ocean by the prevailing winds - building in strength by evaporating water.When the tropical storm meets land, it is no longer fueled by a source of moisture and heat from the ocean and slowed down by friction with land so it loses power and weakens.
What are storm surges?
Tropical storms (rising air) create low barometric pressure causing a localised temporary rise in sea level (1mb pressure = 1 cm change in sea level).Strong winds create larger onshore waves and push a bulge of water inland increasing the damage potential relative to the potential damage caused by surge-induced high water levels alone.
Give five factors that increase the severity of storm surges?
Low lying coastal areas (relief)
Coastal configuration (funneling effect of estuaries/deltas)
Storm track - creation of onshore waves
Intensity of storm - stronger winds = stronger wavesHigh tide
Define short term responses
: immediately before, during or immediately after the hazard e.g. search and rescue and evacuation
Define long term responses
designed to mitigate the impacts of future storms by managing the risks. Includes: prediction; prevention; preparedness and protection (includes mitigation and adaptation).
Give three methods used in the prediction of tropical storms
Geostationary satellites
Land and sea based (NOAA) monitoring
Aircraft reconnaissance
What method has been proposed for the prevention of tropical storms?
Cloud seeding
Give five methods of protection/preparation against tropical storms.
Cyclone/hurricane drills e.g. Project safeside
Land-use planning to reduce public access to hazardous areas
Sea walls, breakwaters and flood defences to reduce storm surge risk
Emergency services drills
Insurance
