Hurricane Hazards and Society 1

A. Hazard and RiskB. Hurricane formationC. Comparing hurricanes and seasons

1. In this cartoon, what are the hazards?

2. How could the person minimize her risk from these hazards?

A. Hazard or Risk?

Geologic Hazard• Phenomenon capable of causing harm to

humans– Tsunami– Flood– Volcanic ash– Lahar– Fire– Liquefaction– Landslide

…. Can you think of others?

Primary Hurricane Hazards- Wind- Storm Surge- Rain- Waves

Secondary Hurricane Hazards(caused by a primary hazard)- Flooding- Fire - Landslides- Coastal Erosion

Risk

The likelihood of a hazard happening to YOUFactors: • Cost – human life– damage to property and infrastructure

• Probability– dependent on location– large events are generally less likely than small

ones Recall: Question for today…

B. Hurricane Formation:Ocean and atmosphere systems interact to

create hurricanes

• Make a list of hurricane characteristics:

What is a hurricane?

What is a hurricane?

• Formal definition:An intense low pressure system with sustained winds >74 mph

What makes a hurricane?

• 4 essential ingredients

What makes a hurricane?

1) Warm SST >26.5°C (80°F) over large area

What makes a hurricane?

1) Warm SST (>26.5 C) over large area

2) Instability in atmosphere (rising air mass)

What makes a hurricane?

1) Warm SST (>26.5 C) over large area

2) Instability in atmosphere (rising air mass)

3) Little/no vertical wind shear through troposphere

(Klotzbach and Gray, 2010)

What makes a hurricane?

1) Warm SST (>26.5 C) over large area

2) Instability in atmosphere (rising air mass)

3) Little/no vertical wind shear through troposphere

4) Sufficient latitude >5-10o off equator

Hurricanes are powered by

• latent heat stored in water vapor– released when water condenses

1. Warm water supplies sensible heat & humidity to overlying air

2. Air decreases density; rises3. Air cools; H2Ovapor condenses

4. Latent heat released-- Heat warms air; rises faster

5. P gradient increases -- Faster winds-- More water vapor into system!

Feedback between the ocean and atmosphere systems!

So… Can hurricanes cross the equator?

• Discuss with the person next to you. • Why or why not?

– Discuss with the person next to you. – Why or why not?

Can hurricanes cross the equator?

(Hurricane tracks 1851-2012; NASA)

North Atlantic Hurricane Season is June-November

Most storms occur in which month?

January

Febru

ary

Marc

hApril

May

June

July

August

September

October

November

December

0

0.5

1

1.5

2

2.5

3

3.5

4

Tropical StormsHurricanesHurricanes w/US Landfall

Ave

rage

num

ber p

er m

onth

, 185

1-20

11

Which of these things would cause a hurricane to lose energy?

a) Moving over colder waterb) Moving over warmer waterc) Making landfalld) Crossing the ocean

As a hurricane approaches land

Wind and rain

Storm surge

As hurricanes make landfall, they decrease in strength

Why?

Remember what fuels hurricanes…

Warm water!

SummaryHazard and riskWhat is a hurricane?

- What 4 conditions are necessary for hurricane formation?- What happens as hurricanes approach land?

Draw:

• the relationships between the ocean, atmosphere, and people in a hurricane