HAZARD - storms Flashcards
what percentage of tropical storms occur in eastern asia?
33%
what areas are particularly prone to storms?
east pacific
west australia
caribbean
typhoon
N HEMISPHERE tropical storms in asia
hurricane
N HEMISPHERE atlantic and north pacific
cyclone
SOUTHERN HEMISPHERE tropical storm in the south pacific and indian ocean
what is the average wind speed needed to be classified as a tropical storm?
75mph
what are the 4 conditions required for the formation of a tropical storm?
- sea water above 27*C
- disturbance in the air, near the sea surface (low pressure)
- convergence of air in the lower atmosphere (warm and cold air)
- corriolis effect , over 5* from equator
how many degrees from the equator are tropical storms able to form?
over 5*
What is the Coriolis effect
force caused by the earths rotation, deflects the path of winds accelerating spinning = circular wind patterns
weak at the equator
diameter of a typical tropical storm
500km
what direction do cyclones turn
anticlockwise - northern hemisphere
clockwise - southern hemisphere
latent heat
heat required to turn solids to liquids to gas
this energy drives the storm
Formation of a tropical storm
- sun warms sea to 27*c
- evaporation of water = warm air rise
- cools, condenses, forms rain clouds
- pressure gradient = cool air rushes in to replace lost warm air
- Coriolis effect- warm air rushed up from sea surface begins to spin
- strong winds carry the storm across the ocean.
what causes tropical storms to become stronger
if the ocean is hot enough
what weakens a tropical storm
moves over land or cooler oceans
ITCZ
intertropical convergence zone
= 5-25*C north and south of the equator
where most tropical storms originate
Storm hazards
high winds= destroy buildings, uproot trees, storm surges = large rise in sea levels heavy rain flooding landslides
what percentage of deaths during a storm are due to storm surges?
90%
saffir-simpson scale
measures the intensity of tropical storms based on the highest wind speed.
category 1 wind speed
74mph 119km/h
category 2 wind speeds
96 mph 154km/h
category 3 wind speed
111 mph 178km/h
category 4
131mph 210km/h
category 5
156mph+ 250km/h+
limitations of the Saffir-Simpson Scale
doesn’t assess the impacts of rainfall or areas affected
lower categories may have larger impacts on vulnerable or highly populated areas.
frequency
recent yrs have seen an increase in numbers of storms
but pattern is erratic
preparedness
train and prepare emergency services for a storm
evacuation routes.
educate
adaption
building design to withstand tropical storms
(reinforced concrete, fix roofs securely)
flood defences
stilts
prevention
impossible
but scientists study storms to understand which areas are at the highest risk so we can avoid them.
has the magnitude increased
in theory it should: increased temp= warmer oceans = moire moisture and therefore more intense storms.
BUT the increased winds act as negative feedback so the magnitude has not increased.
what months of the year are storms most common
august to October
NOAA
national oceanographic and atmospheric administration
how does the NOAA predict tropical storms
sea surface temp, atmospheric conditions, short term climate cycles ( el nino and la nina)
hurricane return period
the frequency at which a hurricane of a given (saffir-simpson )category can be expected to return within a given distance to a certain location.
(other factors are also at play)
social impacts
flooded sewage = water borne disease property damage homelessness looting loss of jobs rise in insurance stress and trauma
economic impacts
cost of repairs
businesses loss of profit
damage crops
oil prices increase due to difficulties in extraction
environmental impacts
damage sensitive ecosystems
fish killed due to silting - freshwater fish killed from storm surge
flooding and mudslides
mitigation strategies
warning systems
evacuation drills
flood defences and schemes
disaster aid
preparedness
increase awareness structural improvements emergency supplies plan evacuation route insurance -risk sharing warning
safe homes programme
insurance department gives grants to improve structural support in homes (USA)
cloud seeding
attempt to dissipate the storm by changing the amount or type of precipitation
but was not affective
storm surge elevation mark
show which buildings are at risk and where to build in the future
land zoneing
flood land is low value and used for recreation
adaptions
land zoning, storm surge elevation mark and building codes
