Tropical Storms
How do tropical storms form?
They form at 8 to 20 degrees (between the tropics of Cancer and Capricorn) due to the easterly
trade winds in the ITCZ converging in the middle, causing the unstable low pressure air to rise over
the Equator, which when passing over seawater of 26/27 average temperature collects moisture.
The moisture rises and condenses as it cools to create a cloud and often thunderstorms, which give
the beginning to a tropical storm. The air rises faster and faster due to the gap between the air and
the water, sucking cooler and dry air downwards. The process of condensation releases latent heat,
making the storm more powerful which further intensifies with the spin of the Earth, creating a
tropical storm- counter-clockwise in the north and clockwise in the south. The eye of the storm can
reach up to 30 miles, a storm is classified as one when it reaches 74kmp/39mph and over (Cat 1 on
Saffir-Simpson scale)
Frequency and Intensity:
Storms with winds over 115mph are 15% more likely to happen in the last 40 years. The area with
the most significant increase in severity/ intensity is the North Atlantic. – 49% increase per decade.
The Indian Ocean also sees a large increase with 18% increase per decade. No clear trend is available
to see, but scientist agree on that climate change will impact storms greatly, supplying them with
more moisture.
, Tropical Storm Characteristics; Impacts- social, Preparedness
Location economic, (mitigation,
environmental and adaptation) and
political Responses-
immediate; long term
Katrina (and Rita) 2005; New Orleans, $160 billion 28th of August- Bush
Louisiana 9th Ward= biggest declared a state of
Formed as a tropical damage as it is the emergency- FEMA had
depression, lowest lying out of all to act- it didn’t!
approaching Florida wards Hurricane Pam was
from the south east The levees supposed to prepare
Reached Cat 5 over surrounding the city FEMA and the
the Gulf of Mexico broke- the eastern residents of Florida for
Max winds- 175mph part was the worst a similar event- week
Gusts of 255mph affected long exercise in July
29th- Cat 4 and when it 600 200 ppl fled = 2004; 175 000 injured;
reached Louisiana- Cat over 50% to Texas- 200 000 sick and over
3 strain on neighbouring 60 000 killed; need of
CAT 5 when it hit NO states 1000+ shelters and
9m storm surge 1500 ppl killed tents- tents were
Why is New Orleans 80% flooded- levees rejected= the
vulnerable? breached simulation was very
Mean elevation of 2m $50 billion damage similar to Katrina
Black population- less adding $3 billion after 31st of August- total
likely to have hurricane Rita which evacuation- except
insurance hit one month after those who had no
At the end 200 000 Pop before Katrina= means- Pam predicted
ppl didn’t have the around 460 000- that some will not be
means to get out and after= 120 000 able to
evacuate Cemeteries broken- The levees are 350
Pumping water from coffins went inland= miles long
acquifers- sinking of disease surrounding the city-
the land+ rise in sea Only 9 petrol stations 20 feet deep into peat
level- more vulnerable operated in the city and channels in
to storm surges- more 236 ppl along the between- made them
intense and bigger Mississippi river died very weak and
Highest and most vulnerable- later a
powerful storm surge study showed that the
went 10 km inland levees are not uniform
and was around 6m walls, but wall
high – left 109 000 ppl segments with
homeless, destroying nothing in between-
their homes the budget for the
AFTER RITA: levees was cut- made
How do tropical storms form?
They form at 8 to 20 degrees (between the tropics of Cancer and Capricorn) due to the easterly
trade winds in the ITCZ converging in the middle, causing the unstable low pressure air to rise over
the Equator, which when passing over seawater of 26/27 average temperature collects moisture.
The moisture rises and condenses as it cools to create a cloud and often thunderstorms, which give
the beginning to a tropical storm. The air rises faster and faster due to the gap between the air and
the water, sucking cooler and dry air downwards. The process of condensation releases latent heat,
making the storm more powerful which further intensifies with the spin of the Earth, creating a
tropical storm- counter-clockwise in the north and clockwise in the south. The eye of the storm can
reach up to 30 miles, a storm is classified as one when it reaches 74kmp/39mph and over (Cat 1 on
Saffir-Simpson scale)
Frequency and Intensity:
Storms with winds over 115mph are 15% more likely to happen in the last 40 years. The area with
the most significant increase in severity/ intensity is the North Atlantic. – 49% increase per decade.
The Indian Ocean also sees a large increase with 18% increase per decade. No clear trend is available
to see, but scientist agree on that climate change will impact storms greatly, supplying them with
more moisture.
, Tropical Storm Characteristics; Impacts- social, Preparedness
Location economic, (mitigation,
environmental and adaptation) and
political Responses-
immediate; long term
Katrina (and Rita) 2005; New Orleans, $160 billion 28th of August- Bush
Louisiana 9th Ward= biggest declared a state of
Formed as a tropical damage as it is the emergency- FEMA had
depression, lowest lying out of all to act- it didn’t!
approaching Florida wards Hurricane Pam was
from the south east The levees supposed to prepare
Reached Cat 5 over surrounding the city FEMA and the
the Gulf of Mexico broke- the eastern residents of Florida for
Max winds- 175mph part was the worst a similar event- week
Gusts of 255mph affected long exercise in July
29th- Cat 4 and when it 600 200 ppl fled = 2004; 175 000 injured;
reached Louisiana- Cat over 50% to Texas- 200 000 sick and over
3 strain on neighbouring 60 000 killed; need of
CAT 5 when it hit NO states 1000+ shelters and
9m storm surge 1500 ppl killed tents- tents were
Why is New Orleans 80% flooded- levees rejected= the
vulnerable? breached simulation was very
Mean elevation of 2m $50 billion damage similar to Katrina
Black population- less adding $3 billion after 31st of August- total
likely to have hurricane Rita which evacuation- except
insurance hit one month after those who had no
At the end 200 000 Pop before Katrina= means- Pam predicted
ppl didn’t have the around 460 000- that some will not be
means to get out and after= 120 000 able to
evacuate Cemeteries broken- The levees are 350
Pumping water from coffins went inland= miles long
acquifers- sinking of disease surrounding the city-
the land+ rise in sea Only 9 petrol stations 20 feet deep into peat
level- more vulnerable operated in the city and channels in
to storm surges- more 236 ppl along the between- made them
intense and bigger Mississippi river died very weak and
Highest and most vulnerable- later a
powerful storm surge study showed that the
went 10 km inland levees are not uniform
and was around 6m walls, but wall
high – left 109 000 ppl segments with
homeless, destroying nothing in between-
their homes the budget for the
AFTER RITA: levees was cut- made
