Learning Objectives:1) To know the cause of tropical revolving storms

(hurricanes/ typhoons/ willy willies)2) To understand how they are formed and the structure

and characteristics of a hurricane.

Hurricanes

Starter: Look at the satellite photo below1) What is this?2) Where do they happen?3) Do they happen in the UK? Why?

Hurricane Katrina, shown in the satellite image, began life as a tropical depression near the Bahamas. As it became more intense, it was upgraded to a tropical storm- and then a hurricane.

Climatic hazard- is a short-term weather event that is a threat to life and property.

(Hurricanes, typhoons, cyclones) are particularly powerful tropical revolving storms. They are intense, destructive, low-pressure weather systems. They have very strong winds of over 120 km/h (75 mph) and torrential rain (250 mm can fall in one day). They are intensely powerful storms capable of devastating large areas and causing considerable damage to property and loss of life. The average lifespan is 7-14 days.

In summer and autumn when sea temperatures are at their highest In tropical regions of severe air instability where air is converging on the surface and

rising rapidly.

Eye- of the hurricane is in the centre of the storm where cooler, denser air sinks down towards the ground. Conditions are deceptively calm and clear.

Eyewall- on either side of the eye is a towering bank of cloud. It is here that the winds are usually at their strongest, and where the heaviest rainfall occurs.

Once formed, the hurricane is carried across the ocean by the prevailing winds, generally from east to west. As it moves it continues to pick up moisture from the sea, becoming even more powerful. On reaching land the supply of water- the hurricane’s fuel- is cut off and the storm begins to weaken.

http://www.bbc.co.uk/learningzone/clips/how-hurricanes-are-formed-by-earth-s-rotation/13531.html

How hurricanes are formed by the Earth’s rotation

http://www.bbc.co.uk/learningzone/clips/how-hurricanes-are-formed/14082.html

How hurricanes are formed

‘Eye’ of the hurricane

Eye wall

Circular shape

Very large size

Anticlockwise spin

North west direction of movement Continuous cloud cover

Broken cloud cover

The effects of hurricanesThey cause great destruction through:

• Strong winds- with sustained wind speeds in excess of 120kph (75mph) and gusts in excess of 200kph (125mph). Roofs are blown off houses, power lines are torn down. Flimsy houses are totally destroyed. The damage to crops could have long-lasting economic consequences.

• Heavy rainfall- there is potential for huge amounts of rain to fall, often in excess of 200mm. This causes widespread flooding as rivers burst their banks. Landslides may be triggered in upland regions.

Storm surge- which are rapid rises in sea level, caused by the low pressure and driven by onshore winds these high sea, often 3m to 5m in height, surge inland over low-lying areas and up river valleys. A storm flattens everything in its path. It destroys crops and inundates vast areas with salty water.

Shock- after the storm dies down, people are in a state of shock from social losses (deaths of relatives and friends. There are also economic losses (damage to homes, possessions and businesses, loss of crops and animals on farms).

Public utilities- are badly disrupted and life can be very difficult without access to electricity, telephones, transport and fresh water. Disruption to fresh water supplies, sewage treatment and waste disposal can lead to serious health problems and the spread of diseases such as cholera and typhoid.

Political- adverse consequences if the government fails to respond well to the disaster.

Extreme Hurricanes- in rich and poor parts of the world

Learning Objective:1) To know two case studies of tropical revolving storms- one from a rich part of the

world and one in a poorer area. 2) To understand the specific storms social, economic and environmental effects

and short and long term responses (monitoring, prediction, protection and preparation.

‘Oh my God. It was hell. We were screaming, hollering, lights were flashing. It was complete chaos’ Kioka said. She had to hack through the ceiling of the shop where she worked as floodwaters rose in New Orleans.

1) What impacts from the photo can you identify that Hurricane Katrina has had?2) Can you identify where New Orleans in on a blank map of the USA? What do you know

about New Orleans

STARTER:

New Orleans, Louisiana

The National Hurricane Centre in Florida:• Provides hurricane predictions to the US states and surrounding countries• Aims to make people more away of the risks they face, and actions to take if the hurricane

hits. They run a Hurricane Preparedness Week every year. In 2010, it ran from 23-29 May• Offers advice to families, and provides Family Disaster Plans.

The job of the Federal Emergency Management Agency (FEMA) in the USA is to reduce loss of life and property. It protects people and places by making sure that areas are prepared for disasters, as well as giving emergency help and aiding recovery.

Protecting New OrleansThe flood defences in New Orleans were left in tatters following Hurricane Katrina’ s onslaught. However, the levees and floodwalls have been repaired and strengthened, floodgates have been built and pumping stations improved. The rebuilding and strengthening work was expected to continue until 2013.

Louisiana has other problems as well as its built defences. Its wetlands are rapidly disappearing and the wetlands provide barriers which absorb the energy of the storm surges and protect inland areas. A plan called Coast 2050 aims to recreate the mixture of swamp, marsh and barrier islands that used to exist in Louisiana, in order to protect places like New Orleans in the future.

http://www.bbc.co.uk/learningzone/clips/hurricane-katrina-modelling-the-consequences/14075.html

Hurricane Katrina – modelling the consequences

http://www.bbc.co.uk/learningzone/clips/new-orleans-levee-failures/14081.html

New Orleans levee failures

http://www.youtube.com/watch?v=HbJaMWw4-2QHurricane Katrina- day by day (causes and consequences- (National Geographic)

http://www.youtube.com/watch?v=LXAF8AjgiWM

Cyclone aftermath in Myanmar - 05 May 2008

http://www.youtube.com/watch?v=H55mFbPdWeM

Nargis Cyclone CNN News

Track: the path or course of a hurricane.

Responses• Meteorologists can watch tropical storms continuously thanks to weather satellites;

warnings can be given to evacuate areas.• Police and fire services can practise emergency drills• People can be educated in advance about emergency procedures• Emergency shelters can be prepared with rations of food and water

The behaviour of tropical storms is notoriously unpredictable; they can suddenly become stronger and change direction. • Some people are always unwilling to leave their homes and property unattended. • Others are too poor or do not have the means of transport to move inland out of the

storm’s reach. Theory and reality can be two different things.