Transcript Hurricane Revisionx

Extreme Weather: Hurricanes
Hurricanes
Aims:
To be able to describe where Hurricanes and Tropical Storms form and
explain why they form in these locations.
Explain what they need to occur and makes them more likely.
Revise the Impacts and Responses to Hurricane Katrina
Suggest reasons why HICs cope better with weather Hazards than LICs
Use this presentation to add to your revision work!
Follow the hyperlinks.
Add to your notes.
What is Hurricane?
What is a Tropical Storm or Cyclone?
Hurricanes are Tropical Storms
What are Tropical Storms?
Tropical Storms are areas of extreme low pressure.
This means air is rising, causing 'low pressure' on the earth's surface.
This generates High Winds.
The maximum sustained surface wind speed ranges from 34 knots (39 mph or
63 kph) to 63 knots (73 mph or 118 kph).
Where do Tropical Storms form?
Whirly-Whirly
The strongest tropical storms are called hurricanes,
typhoons or tropical cyclones. The different names
all mean the same thing, but are used in different
parts of the world. If these huge storms start in the
Atlantic, off the west coast of Africa, they are called
hurricanes.
Tropical storms have different names according to where they form.
Each one is then given it’s own name so it can be tracked by
meteorologists to forecast where they will travel and warn people of
the hazards they could cause.
Where do Tropical Storms form?
Tropical storms form between approximately 5° and 30° latitude North or
South of the equator.
How Tropical Storms like Hurricanes form?
The hurricane formation story
The warm air from _________ and the
deep, warm ocean surface (greater than
27 degrees) _____ __________ and
start to rise to create low pressure.
Trade winds at the equator cause the
storm to ______ due to the Earth’s
____________.
Air continues to rise and the
__________ starts to decrease at
higher altitudes.
Air rises faster and draws in more
______ ______ from the sea surface
whilst sucking cooler air downwards.
As the storm moves over the ocean, it
picks up more warm moist air. The
speed of its winds _________ as more
air is sucked in.
It can take hours or days to fully form
a hurricane. The eye has _____ winds
which are surrounded by a _________
________ of high winds and heavy rain.
Print and
use this
sheet to
create a
Hurricane
Formation
Revision aid
Why do Hurricanes form here?
• Fill in the story board whilst watching the Hurricane animation.
Click link above for
animation
Did you get
them all?
The hurricane formation story: Answers!!
Update your
sheet
Add
illustrations
to help
describe
each point!
The warm air from thunderstorms and
the deep, warm ocean surface (greater
than 27 degrees) mix together and
start to rise to create low pressure.
Trade winds at the equator cause the
storm to spin due to the earth’s
rotation.
Air continues to rise and the pressure
starts to decrease at higher altitudes.
Air rises faster and draws in more
warm air from the sea surface whilst
sucking cooler air downwards.
As the storm moves over the ocean, it
picks up more warm moist air. The
speed of its winds increase as more air
is sucked in.
It can take hours or days to fully form
a hurricane. The eye has calm winds
which are surrounded by a spinning
vortex of high winds and heavy rain.
What conditions are needed for hurricanes to form?
• Tropical Storms start within 8º and 15º north and south of the equator
where surface sea temperatures reach 27ºC.
• The air above the warm sea is heated and rises. This causes low
pressure.
• Sea depths of at least 50 metres
How do hurricanes form? What do they need?
How do tropical storms form?
Hurricanes need a lot of heat to form, which is why they
usually occur over tropical seas (at least 26°C). Tropical
storms usually form between approximately 5° and 30°
latitude and move westward due to easterly winds
The sun is close to the equator, providing energy to heat
the ocean.
The warm ocean heats the air above it causing it to rise
rapidly.
Water evaporates quickly from the hot surface of the
ocean, so the rising air contains great amounts of water
vapour.
The rising air starts to spin (clockwise in the northern
hemisphere). The Coriolis force sends them spinning
towards the poles.
The centre of the storm - the eye - is calm.
As the air rises it cools, condenses and forms towering
cumulonimbus clouds.
The rapidly rising air creates an area of intense low
pressure. The low pressure sucks in air, causing very
strong winds.
Once the storm moves over land it starts to lose energy
and fades.
Warm water heats the air causing it to rise really quickly,
then it gets pushed aside as it cools.
This pushing causes the clouds to spin.
When does it become a hurricane?
Hurricanes are tropical storms where the winds get faster
than 118 km/h (73 mph).
The storms have a central area of calm known as the
"eye", which is the funnel through which the warm air
rises.
Overland, the storms no longer have warm water to power
them and die out within a few days, but not before winds
do a lot of damage.
What causes Tropical Storms like Hurricanes
to spin?
Q. Why do Tropical Storms like
hurricanes Spin?
A. The Coriolis Effect!
The rotation (spin) of the earth “bends” the
winds to the right in the Northern hemisphere
and left in Southern hemisphere. This causes
tropical storms to spin.
Watch this clip from the BBC’s Orbit: Earth's
Extraordinary Journey.
It helps to explain how hurricanes form and are made
to spin by the Coriolis effect…
What are Hurricanes typhoons
and tropical cyclones?
For this activity you will watch
a video clip, make notes from
the clip.
Click link above for
the video clip
Case Study: Hurricane Katrina
Hurricane Katrina was a devastating storm
that hit the area around New Orleans, USA,
on 25 August 2005. It had social, economic
and environmental impacts.
New Orleans is in the United
States of America.
The USA is a Most
Economically Developed
Country.
Katrina 25 August 2005
Katrina was a category 4 storm.
Storm surges reached over 6 metres in height.
New Orleans was one of the worst affected areas because it is
below sea level and protected by levees. These protect it from
the Mississippi River and Lake Ponchartrain. The levee defences
were unable to cope with the strength of Katrina, and water
flooded into the city.
Despite an evacuation order, many of the poorest people
remained in the city.
People sought refuge in the Superdome stadium. Conditions
were unhygienic and there was a shortage of food and water.
Looting was commonplace throughout the city.
Tension was high and many felt vulnerable and unsafe.
1 million people were made homeless. and about 1,200 people
drowned in the floods.
Oil facilities were damaged and as a result petrol prices rose in
the UK and USA.
What Impacts did Hurricane Katrina have?
Social impacts of the hurricane (effects on people)
1,800 people died.
300,000 homes were destroyed.
3 million people were left with no electricity.
People had to move out of the area.
Economic impacts of the hurricane (effects on money and jobs)
$300 billion of damage.
Oil platforms were destroyed.
Shops were looted.
Fuel prices rose.
Tourism decreased.
Environmental impacts of the hurricane
The storm surge flooded large areas of the coast.
80% of New Orleans flooded as man-made levees (Embankments used as flood defences).
overwhelmed by extra water, broke.
Cotton and sugar cane crops were destroyed.
Delicate coastal habitats were destroyed.
Tornadoes were created.
Cause
Hurricanes start when
Economic Effects
strong clusters of
Environmental Effects
thunderstorms drift
In total, Hurricane Katrina
The storm surge
over warm ocean
caused over $81 billion
caused substantial
water.
worth of damage, making it
beach erosion, in some
the costliest Atlantic
cases completely
hurricane ever.
devastating coastal
The seas surface
temperature was at
least 27 degrees
Social Effects
The storm forced
over a million people
to leave their homes.
areas.
More than 91% of oil
production in the Gulf of
Significant amounts of
80% of the city was
Mexico region has been
industrial waste and
flooded and over a
Very warm air from an
shut down because of
raw sewage spilled
million homes were left
ocean storm and the
damage to rigs caused by
directly into the local
without electricity.
ocean surface combine
the hurricane reducing
environment.
and begin to rise
economic activity.
The hurricane caused the
Oil spills from offshore
destruction of many shops
rigs into the ocean
Trade winds blowing in
and services within New
caused significant harm
from opposite directions
Orleans having catastrophic
to the animals and plants
cause ocean storms to
impacts on the areas
that live in and around
start spinning.
economic activity.
the Gulf of Mexico.
Celsius.
creating low pressure.
Over 1,800 deaths were
caused by the storm,
around 700 of them in
New Orleans.
Make sure you
can explain the
causes and
describe social,
economic and
environmental
effects.
Responses to the Disaster
There was much criticism of the authorities for their handling
of the disaster.
Although many people were evacuated, it was a slow process
and the poorest and most vulnerable were left behind.
$50 billion in aid was given by the US government.
The UK government sent food aid during the early stages of the
recovery process.
The soldiers from the US National Guard were mobilised to
restore and maintain law and order in what became a hostile
and unsafe living environment.
Hurricane Katrina Day by Day
Watch this national Geographic video clip telling the story of Hurricane Katrina.
Add to your Day by day account of the event.
Day
What is
hurricane
Katrina
doing?
Effects
and
problems?
Response?
What are
people
doing?
Wednesday
24th August
Thursday
25th
August
Friday 26th
August
Saturday
27th August
Sunday 28th
August
Monday
29th August
Tuesday
30th August
Wednesday
31st August
Thursday
1st
September
Friday 2nd
September
Aftermath
Why can more developed countries (MEDCs
and HICs) cope better with Weather Hazards
like tropical storms better than less
developed countries (LEDCs and LICs)?
Why can more developed countries (MEDCs and HICs) cope better with
Weather Hazards like tropical storms better than less developed
countries (LEDCs and LICs)?
Preparation and prediction
Preparation and prediction techniques to help cope with hurricanes can be very different in MEDCs and LEDCs.
MEDCs have the resources and technology, such as satellites and specially equipped aircraft, to predict and
monitor the occurrence of storms. They are also equipped to train the emergency services appropriately and to
educate people about necessary precautions.
Storm warnings can be issued to enable the population to evacuate or prepare themselves for the storm. People
can prepare by storing food and water or boarding up their windows.
LEDCs are often less prepared. They may not be able to afford forecasting and prediction technology to warn
people of the hazard. They may not be able to afford or to make preparations for a weather hazard by storing
food or clean water. They may not be able to afford adequate emergency services to cope with a disaster.They
may rely on aid (sometimes reluctantly) from MEDCs for the rescue and recovery process, as was the case with
Cyclone Sidr in Bangladesh, November 2007.
Glossary
Coriolis Effect- An apparent force, due to the spinning of the Earth, which deflects
movement of particles and wind. It causes tropical storms to spin.
Evacuation -When people are moved from an area, often temporarily and for
their safety.
Habitat- Place where plants, animals and microorganisms live.
Levee- Ridges or banks formed by deposits of alluvium left behind by the periodic
flooding of rivers. Can also be artificially constructed banks or walls.
Storm Surge – When sea level rises above the normal tidal range.