Tropical storms form over warm tropical oceans between 5 and 20 degrees north and south latitude. They require warm sea surface temperatures of 26 degrees C or more and generally occur in late summer and early autumn. Hurricane Katrina formed in late August 2005 and rapidly intensified into a category 5 hurricane over the Gulf of Mexico before making landfall and causing catastrophic damage, especially in New Orleans. Katrina was one of the costliest and deadliest hurricanes in U.S. history, resulting in over 1,800 deaths and over $150 billion in damages.

1. Tropical Storms
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2. Index
• What are Tropical Storms?
• How and Where do they form?
• Main Features of a Tropical Storm.
• Recent Tropical Storms
• Case Study: Hurricane Katrina, 2005.
• Destructiveness of Tropical Storms
• Summary
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3. What are Tropical Storms?
• Tropical storms are areas of intense low pressure.
• They produce violent weather with high winds (The
average speed is 120 km/h. Although it may vary from
32 km/h to 200 km/h or more. At times it reaches 400
km/h also), thick cloud and torrential rain.
• Depending on where they are in the world they can
also be called:
– Hurricanes
– Cyclones
– Typhoons
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4. How and Where do they Form?
• There are three main criteria needed for a
tropical storm to develop:
- Warm Tropical Oceans (Temperature of 26 C or more)
- Late Summer early Autumn where sea temperature is
optimum.
- In Certain Latitudes: 5 -20
North and South.
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8. Main Features of Tropical Storms
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10. • Warm air and water vapour is ‘sucked’ up
from the oceans in the centre of the storm
cell.
• This air then cools and as it condenses it forms
clouds and then releases its huge energy that
powers the storm.
• Once the storm makes landfall the source of
heat (the ocean) is lost and the storm
decreases in strength.
• Tropical storms tend to move westwards when
over seas and polarly once they have hit land.
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11. • Tropical Storms are at their most powerful
either when at sea or at landfall due to the
presence of thermal energy.
• Due to the high winds present, storm surges
are common and these increased depending
on the category of the storm.
• Tropical Storms are categorised according to
the Saffir-Simpson Hurricane Scale based on
their wind Speeds and resulting damage.
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15. Recent Powerful Tropical Storms
• Typhoon Haiyan, Philippines- November 2013
• Hurricane Sandy, North-East USA, October 2012
• Hurricane Katrina, South-East USA, August 2005
• Hurricane Ivan, South-East/East USA, September
2004.
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16. Case Study: Hurricane Katrina
• Hurricane Katrina formed as Tropical Depression
over the south-eastern Bahamas on August
23, 2005.
• The tropical storm moved towards Florida, and
became a hurricane only two hours before it made
landfall on August 25.
• It weakened over land but soon ended up in the
Gulf of Mexico where it regained it’s Strength, going
from category 3 to 5 in 9 hours.
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Below: The Course of Hurricane
Katrina, 2005
Left: The Saffir-Simpson Hurricane Wind
Scale used to measure the Category of
Hurricanes.

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19. Hurricane Katrina Over New Orleans
• New Orleans is the largest city in the state of Louisiana.
• It is located 2-6m below sea level which is why
Hurricane Katrina was so devastating.
• Over New Orleans Katrina had:
– Wind Gusts over 175miles per hour (over 280km/h)
– Levees protecting the city from flooding collapsed due to the
wind and storm surge (7 Feet High) produced by Katrina
– An estimated 80 percent of New Orleans was under
water, up to 20 feet deep in places.
– The centre eye had extremely low pressure: 920 mbar.
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22. Destructive Results of Katrina
• Despite an evacuation order, many of the poorest people remained in
the city.
• People sought refuge in the Super Dome stadium. Conditions were
unhygienic
• shortage of food and water.
• Looting was commonplace throughout the city.
• The final death toll was at 1,836: Louisiana (1,577) /Mississippi (238)
• 1 million people homes destroyed $81 billion in damages.
• Oil facilities were damaged and as a result petrol prices rose in the UK
and USA.
• Total Estimated Damages exceeded $150 billion in Louisiana and
Mississippi alone.
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25. Summary
• Tropical Storms can only be found in the Lower
latitudes between 5 -20 North and South where sea
temperature exceeds 27 C.
• They usually occur between late summer and early
Autumn.
• Hurricane Katrina was one of the most destructive
Tropical storms ever to hit Mainland USA.
• It is a pure example of how quickly a ‘contained’ storm
can change into a cataclysmic event.
• The storm showed just how costly Tropical storms
could be, with an estimated damage cost exceeding
$150billion.
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