Hurricanes

Weather Hazards

Know how hurricanes are formed.How Hurricanes are named.Weather patterns of Hurricanes.Factors necessary for their development.The stages of development.Long and short term effects.Characteristics of a Hurricane.Case study Hurricane Katrina.By the end of this section, you will: What are the causes and effects of hurricanes?

Hurricanes

Scoop It Click here for a playlist on hurricanes

Boardworks Ltd 2008# of 381

FAMILY OF TROPICAL CYCLONES INFRARED SATELLITE PHOTOGRAPH


HurricanesWhat is a hurricane?

A violent cyclonic storm that develops in the tropical regionwith wind speeds are > 74 mph lasting for several days.

In which direction doesa hurricane rotate?

Counterclockwise (NH)Clockwise (SH)

Is the pressure inside the hurricane high or low?

Low


How are hurricanes classified?


How do hurricanes form?

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Hurricane formation



Naming of Hurricanes


Tropical Cyclone StructureDoppler radar showing hurricane main parts:Eye

Eyewall

Rainbands.

Counter-clockwise rotation. (NH)

In very center of the storm, air sinks, forming an "eye" that is mostly cloud-free.


High HumidityUnstable AirLittle Surface FrictionSea temperature of at least 27 CLight Variable WindsLow air pressureDivergence of air in upper levelsComplete the following details! Go into editing mode to do so.Necessary factors for the formation of Hurricanes

Heat is needed for convection

Factor or Condition

Influence on formation process

Latent heat is released during condensation

Unstable air to cause rising / convection of air

Friction slows down the movement of the Tropical Cyclone

Strong winds inhibit the development of the vortex

Rising air associated with a LP is required for cloud formation

Stimulates circulation and the formation of votices

Boardworks Ltd 2008# of 389Teachers note: These are just some of the many facts and figures that relate to the damage and destruction caused by Hurricane Katrina. You may wish to expand upon the facts and figures noted here. For more information about Hurricane Katrina, please see: http://news.bbc.co.uk/1/shared/spl/hi/americas/05/katrina/html/default.stmhttp://www.hhs.gov/disasters/emergency/naturaldisasters/hurricanes/katrina/index.html

Boardworks Ltd cannot take responsibility for the content of external websites.

Photo credit: National Oceanic and Atmospheric Administration (NOAA)

TROPICAL CYCLONE: DEVELOPMENT

Formative Stagepressure ABOVE 1000 hPa

Developing StagePressure BELOW1 000 hPa

MATURE Stagepressure WELL BELOW1 000hPa

Degenration/DissipationStagepressure RISES

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TEMPERATURECLOUD COVER, RAINWINDAIR PRESSUREAREA INFLUENCED

LP develops over the sea. Pressure is above 1000 hPas. Convergence of air. Vortex forms

High temperatures and humidity that release latent heat and strengthen the LP.

Cirrus and Cumulus clouds. Light rain.

Winds in active quadrant reach speeds of gale force winds.

Small area is influenced,20 km from the eye.

TROPICAL CYCLONE: ASSOCIATED WEATHER CONDITIONS

FORMATIVE STAGEComplete the following details! Go into editing mode to do so.






DEVELOPING STAGEComplete the following details! Go into editing mode to do so.






MATURE STAGEComplete the following details! Go into editing mode to do so.






DEGENERATION STAGE / DISSIPATING STAGEComplete the following details! Go into editing mode to do so.




Stages of Development

How do you know a Hurricane is in the dissipating stage?(Go into editing mode and complete the following:

1)

2)

3)


Most dangerous part of the Hurricane


Eye of a Hurricane


Eye of a Hurricane.


Development of Tropical Cyclones

L

2) Convergence of air forces air to rise3) As air rises, moisture condenses out, warming air and allowing it to continue rising

L5) As pressures decrease, winds intensify and even more warm moist air is forced to converge and rise4) As air rises, it causes even lower pressures at the surface1) Warm, moist air spirals towards center of Hurricane


Short-term effects will normally only last a few days or weeks. They will not cause any lasting or permanent damage. Examples may include:slight damage to land and/or buildingstemporary migration of the populationa disruption to power supplies.Can you think of any other short-term effects that might arise?

In the short-term

Boardworks Ltd 2008# of 3820Teachers note: Some short-term effects might include temporarily blocked roads, flooded fields, a lack of electricity, disruption to public transport, etc. Some sample short-term effects have been shown in the Flash activity on slide 7.

Photo credit: 2008 JupiterImages Corporation

Long-term effects can include large-scale destruction of property, or a complete alteration of the physical landscape.These pictures show the Chandeleur islands in the USA before and after Hurricane Katrina. As you can see, their geography has been permanently altered by the hurricane.

Can you think of any other long-term effects that might arise?The long run

Boardworks Ltd 2008# of 3821Teachers note: Some long-term effects might include land being lost to the sea, landslides altering the appearance of the landscape, a hurricane/tornado destroying a town, etc. Some sample long-term effects have been shown in the Flash activity on slide 7.

The worksheet Short-term Long-term accompanies this slide.

Photo credit: NASA

Long and short term effects of Hurricanes

Fill in the Short and Long-term effect!


Equator/Ewenaar

From EAST to WESTTurns EAST at 30

DESTRUCTIONStorm windsTorrential rainFlooding

DISSIPATESNo MoistureNo warm airFrictionOCCURTropicsOceanFurther 5- 25

EYENo wind, rain & CloudsAway from equatorCharacteristics of a Tropical Cyclone



MOVEMENTFrom E to WAway from EquatorTurns east at 30

DISSIPA-TIONOver landNo MoistureNo Warm airFriction

MANAGEDSand bagsEarly warningTrack stormServicesInform peopleEvacuation

NAMEAlphabetAndrewBonnyCarlDebora

ORIGINIn tropicsOCEANSNot nearerthan 5N/S fromequator

DESTRUC-TIONStorm windsVery hard rainFlooding

IN EYENo :WindCloudsRain

WEATHER

Before eyeDuring eyeAfter eye

Characteristics of a Tropical Cyclone



Movement (direction):Rotation:Wind belt:Originate (Latitude): Diameter:Weather:Named:

Complete the following details! Go into editing mode to do so.Characteristics of a Hurricane!

Caused by:




TROPICALCYCLONE - MANAGEMENT



Dwellings very close to rivers / floodplains should be evacuated.Farmers should move pumps away from rivers.Avoid crossing strongly-flowing rivers at causeways /drifts. Small / medium sized fishing boats should return to port.Small fishing boats should be moved well above the high water mark.

What precautions should be taken when there is a Hurricane warning!Preparing for the worst!Listen to the advice of the local disaster risk management officials.

Listen to the radio / television for weather reports.




It hit New Orleans on the morning of the 29th August 2005 bringing with it terrible destruction.Winds of over 250 kilometres per hour were recorded as Katrina hit the coast, causing a storm surge 8.5 metres high.

New Orleans

Hurricane Katrina was the most powerful hurricane to hit the USA in known history.Hurricane Katrina

Boardworks Ltd 2008# of 3828Photo credit: (bottom left) NASA/Jeff Schmaltz, MODIS Land Rapid Response Team

Photo credit: (top right) Brianski. This image is reproduced under the terms of the GNU Free Documentation License. A copy of the license can be read at this address: http://commons.wikimedia.org/wiki/Commons:GNU_Free_Documentation_License

At first New Orleans seemed to have weathered the worst of the hurricane, but later storm surges breached the citys protective levees.

People that had not left their properties were stranded and had to wait to be rescued or wade through polluted floodwater.

It was a hugely devastating natural disaster.Devastation

Boardworks Ltd 2008# of 3829Photo credit: Image courtesy of the United States Federal GovernmentPhoto credit: Image courtesy of Federal Emergency Management Agency (bottom)

80% of the city was flooded.Over a million homes were left without electricity.There were 700 deaths in New Orleans.Flood levels were over six metres high.Over a million people had to leave their homes.Damaged oil refineries spilt 24 million litres of crude oil.Over $81 billion worth of damage was done.

How badly did Hurricane Katrina affect New Orleans?The aftermathClick here for a PowerPoint on Hurricane Katrina




In the news



You are the mayor


Boardworks Ltd 2008# of 3832Teachers note: This Flash activity has no right or wrong answers. Instead, after making each decision, students will be asked to explain why they took this decision and what the pros and cons were for each of the decisions. The five dilemmas included in the activity are based on decisions that the mayor of New Orleans, Ray Nagin, had to make. The activity is not designed so that students have to follow any correct path. It is instead intended to get them really thinking about the implications of all the decisions that had to be made. Students should also be urged to consider the significance of these decisions and remember that the decisions made by the mayor and the President had a very real effect on peoples lives.

The worksheet Hurricane Katrina accompanies this slide.


Give ONE similarity between Hurricanes and Tropical cyclones on the map.Explain the point of origin of both hurricanes and tropical cyclones on the map.Why do these tropical cyclones move from east to west?Why do tropical cyclones weaken as they move over Madagascar.Why is the impact of tropical cyclones more severe in developing countries?EXAMINATION QUESTION

Coriolis forceWarm waterMoistureTropicaleasterlies

LandNo warm waterFrictionsource: http://sageography.myschoolstuff.co.za


Hurricanes

Education

Transcript of Hurricanes