HURRICANES
AND Tornadoes
What is a hurricane?
 Violent
cyclonic storm
that develops
in the tropical
region
 Wind speeds
are > 74 mph
Source: http://earthobservatory.nasa.gov/
Newsroom/NewImages/images.php3?img_id=680
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A tropical cyclone is a storm system
characterized by a low pressure center and
numerous thunderstorms that produce strong
winds and flooding rain. A tropical cyclone feeds
on heat released when moist air rises, resulting
in condensation of water vapour contained in
the moist air. They are fueled by a different heat
mechanism than other cyclonic windstorms such
as nor'easters, European windstorms, and polar
lows, leading to their classification as "warm
core" storm systems
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The term "tropical" refers to both the
geographic origin of these systems, which
form almost exclusively in tropical regions of
the globe, and their formation in Maritime
Tropical air masses. The term "cyclone" refers
to such storms' cyclonic nature, with
counterclockwise rotation in the Northern
Hemisphere and clockwise rotation in the
Southern Hemisphere. Depending on their
location and strength, tropical cyclones are
referred to by other names, such as
hurricane, typhoon, tropical storm, cyclonic
storm, tropical depression, or simply as a
cyclone.
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While tropical cyclones can produce extremely
powerful winds and torrential rain, they are also able
to produce high waves and damaging storm surge.
They develop over large bodies of warm water and
lose their strength if they move over land. This is the
reason coastal regions can receive significant damage
from a tropical cyclone, while inland regions are
relatively safe from receiving strong winds. Heavy
rains, however, can produce significant flooding
inland, and storm surges can produce extensive
coastal flooding up to 40 kilometres (25 mi) from the
coastline.
Although their effects on human populations can be
devastating, tropical cyclones can also relieve
drought conditions. They also carry heat and energy
away from the tropics and transport it toward
temperate latitudes, which makes them an important
part of the global atmospheric circulation mechanism.
As a result, tropical cyclones help to maintain
equilibrium in the Earth's troposphere.
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What is a Hurricane? - YouTube
CYCLONIC STORMS-DIFFERENT
NAMES in DIFFERENT OCEANS:
Atlantic Hurricane, Pacific Typhoon,
Indian Ocean Cyclone
Rotation and Pressure
In which direction does a hurricane rotate?
COUNTERCLOCKWISE
Is the barometric pressure inside the
hurricane high or low?
LOW
When is Hurricane Season?
st
1
June
through
November
31st
What is the role of the
National Hurricane centers
during hurricane season?
Provides weather information, such
as data from satellites
 Responsible for issuing watches
and warnings to the media and
general public
 The US Hurricane Bureau is in
Miami. Canada’s is in Dartmouth!
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Watch vs. Warning
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What is the difference between a
Hurricane Watch and a Hurricane
Warning?
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Watch – Tropical storm poses a threat to
coastal areas with 36 hours
Warning - Tropical storm conditions are
expected in a coastal area within 24 hours
What conditions must be present
for a hurricane to develop?
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Source: http://lwf.ncdc.noaa. 
gov/oa/reports/fran/fran.html
Warm ocean
temperatures (>26˚C) up
to 60m deep
Little to no wind shear
Low pressure system at
least 5˚ North or South of
Equator
Rotation caused by winds
Even George Clooney loves
them!
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The Perfect Storm
The Perfect Storm - The Final Fight –
YouTube
The Giant Wave - The Perfect Storm (3/5)
Movie CLIP (2000) HD - YouTube
What is the major source of
energy fueling a hurricane?
Heat Energy evaporating from the
ocean surface
Source: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hyd/evap.rxml
Hurricane Anatomy
Source: http://hurricanes.noaa.gov/prepare/structure.htm
Another look at the Structure
Source: http://hurricanes.noaa.gov/prepare/structure.htm
Comparison of Terms
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Tropical Disturbance
Group of thunderstorms in the tropics that are
present for at least 24 hours
Tropical Wave
lack of circulation, winds <25 mph and every
direction
Tropical Depression
closed circulation but disorganized, winds at
least 25 mph
Comparison of Terms
Tropical Storm
Shower and thunderstorm moves over closed
circulation, winds greater than 39 mph
Hurricane
Eye is developed, winds > 74 mph
Compare the Following
Source: http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/stages/home.rxml
By what two factors is hurricane
strength measured?
Wind Speed
Barometric Pressure
What is the Scale Used to
Categorize Hurricanes?
Saffir-Simpson Scale
Category
Max Wind Speed
(mph)
Min. Surface
Pressure (mb)
Storm Surge m
(ft)
1
74-96
> 980
1-1.7 (3-5)
2
97-111
979-965
1.8-2.6 (6-8)
3
112-131
964-945
2.7-3.8 (9-12)
4
132-155
944-920
3.9-5.6 (13-18)
5
> 155
< 920
> 5.7 (>19)
Source: http://kids.earth.nasa.gov/archive/hurricane/saffir-simpson.html
What causes the
damage in a hurricane?
Winds
Flooding
Storm
Surge
What is a storm surge?
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Large wall or dome of
water that rushes into
the coastline as a
result of a hurricane
making landfall
To the right are the
areas affected by high
storm surges
Souce: http://www.wkrg.com/hurricanecenter/surge/SE.jpg
What destroys a hurricane?
 Strong
vertical winds
 Cold water
 Movement over land
Friction
Lack of moisture
Explain why the majority of the
costliest storms are relatively recent
Damage is a
result of
development
 There are more
developed areas
and possessions
than in the past
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Source: http://www.nhc.noaa.gov/1992andrew.html
The deadliest storms were long
ago.
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Lack of instrumentation to predict and track
storms
People were not warned of the incoming
danger
Results of the Galveston Hurricane
Source: http://www.1900storm.com/photographs/photo10.html
How do they decide the names
of Hurricanes?
Alex
Bonnie
Colin
Danielle
Earl
Fiona
Gaston
Hermine
Igor
Julia
Karl
Lisa
Matthew
Nicole
Otto
Paula
Richard
Shary
Tomas
Virginie
Walter
http://www.livescience.com/34518hurricane-names-2013.html
Protection
 Listen
to warnings
 Take all warnings seriously
 Follow evacuations
 Prepare Food and Water for
extensive power outages
Source: http://www.dc.peachnet.edu/~pgore/students/w97/matheson/hpage.htm
Hurricane Juan-Halifax
Hurricane Juan was a significant tropical cyclone that caused
heavy damage in Canada in late September 2003. It was the
tenth named storm and the sixth hurricane of the 2003
Atlantic hurricane season. Juan formed southeast of Bermuda
on September 24 from a tropical wave that had tracked across
the subtropical Atlantic Ocean. It tracked northward and
strengthened over the warm waters of the Gulf Stream,
reaching Category 2 strength on the Saffir-Simpson hurricane
scale on September 27. The hurricane peaked in intensity with
sustained winds of 105 mph (165 km/h) that same day, losing
some strength as it raced over cooler waters toward the coast
of Nova Scotia.
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Juan made landfall between Shad Bay and Prospect in
the Halifax Regional Municipality early on September 29
as a Category 2 hurricane with winds of 100 mph (160
km/h).[1] Juan retained hurricane strength while
crossing Nova Scotia from south to north, though it
weakened to a tropical storm over Prince Edward Island.
It was absorbed by another extratropical low later on
September 29 near Anticosti Island in the northern Gulf
of Saint Lawrence.
The hurricane inflicted extensive damage across central
Nova Scotia and into Prince Edward Island, with lesser
damage east and west of the storm centre. Most of the
damage occurred as a result of the intense winds that
buffeted the region. Juan's passage resulted in 8
fatalities and over CA $300 million (US $200 million) in
damage. It was described as the worst storm to hit
Halifax since 1893
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Unforgettable Weather: Hurricane Juan YouTube
Forces of Nature -- Hurricane Juan hits
Nova Scotia - YouTube
Hurricane Juan Halifax, CBC NEWS YouTube
Hurricane Juan 2003 - Hailfax, Nova Scotia
– YouTube
HURRICANE KATRINA
NEW ORLEANS
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Hurricane Katrina Day by Day
Hurricane Katrina - YOU MUST WATCH
THIS - YouTube
Kanye West Hurricane Katrina – YouTube
Kanye West revisits "George Bush doesn't
care" remarks – YouTube
George Bush anger at Kanye West's
'Racist' Remark Memoir – YouTube
Hurricane Sandy, New Jersey-NY
2012
Super Storm Sandy : An Inside Look at Hurricane
Sandy (Full Documentary) – YouTube
Hurricane Sandy: The Documentary - YouTube
Tornados vs. Hurricanes
What causes tornados? - Weather - Weather News - msnbc.com
WHAT DO HURRICANES AND
TORNADOES HAVE IN
COMMON?
 Low
Pressure
 Strong Winds
 Hazardous to Life and
Property
HOW DO THEY DIFFER?
 Location:
T- inland H-coastal
 Size: H- Much wider
 Duration – H- last longer
 Season of Occurrence – H- Autumn
T- Spring
WHEN DO THEY OCCUR?
 Hurricane
 Late
season
Summer and Fall
 Tornado
 Spring
season
and Early Summer
 Hurricanes
form over warm (80 °F)
tropical seas
 Latitude
7-15 degrees North and South of
the equator
 Tornadoes
form over land in the
mid-latitudes
HURRICANE DAMAGE
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High winds
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Torrential rains
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75-125 mph
Flash floods
Storm surges as
sea level rises
HURRICANE CLASSIFICATIONS
Category
 Category
 Category
mph
 Category
mph
 Category
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One -- Winds 74-95 mph
Two -- Winds 96-110 mph
Three -- Winds 111-130
Four -- Winds 131-155
Five -- Winds greater than
155 mph
LOCATION OF TORNADOES
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Most common in the United States
Plains States, Midwest, and Florida
In advance of a cold front
Embedded in hurricanes
Also occur regularly in the Prairies and Ontario
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Tornado Alley is a colloquial term for the area of the
United States where tornadoes are most frequent.
Although an official location is not defined, the areas in
between the Rocky Mountains and Appalachian
Mountains are the areas usually associated with it.
Though no state of the world is entirely free of
tornadoes, they occur more frequently in the plains
between the Rocky and Appalachian Mountains.
According to the storm events database of the National
Climatic Data Center, Texas reports more tornadoes than
any other state, though the very large land area should
be taken into account. Kansas and Oklahoma are second
and third respectively for sheer numbers of tornadoes
reported but report more per land area than Texas.
However, the density of tornado occurrences in northern
Texas is comparable to those in Kansas and Oklahoma.
Florida also reports a high number and density of
tornado occurrences, though tornadoes there rarely
approach the strength of those that sometimes occur in
the southern plains
Tornadoes
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No one knows for sure why the sky changes color before a tornado. But
there are a couple of theories that suggest what creates the strange
greenish-yellow color that (sometimes) precedes a storm.
To understand the first theory, you’ve got to picture mountains. Mountains
in the distance often look a deepening blue. That blue color stems from the
scattering of light by air molecules – it’s the same reason the sky looks
blue. Some experts think that, before a thunderstorm, golden-reddish light
from the sun low in the sky and a natural bluing effect of the air combine to
create a green sky. The storm provides a dark backdrop and offsets this
greenish or yellowish hue.
A different meteorological theory holds that storm clouds themselves may
help make the color of the sky bluish-green. To understand this theory, you
first need to know that water is intrinsically blue (sometimes you can see
the bluish tint of water in a white bathtub). It could be that the storm
clouds — which are filled with water — provide the color blue, which, again,
is illuminated by the golden light of a low sun to create the color green.
SIZE AND DURATION OF
TORNADOES
 Narrow
intense storm
 1/4 mile wide
 Path of 6 miles SW to NW
Tornado Hazards
Wind Speed up
to 300 mph
(480 km/h)
 Strong updraft in
the funnel
 Explosions due
to pressure
contrast
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Fujita Pearson Tornado
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Scale
F-0: 40-72 mph, chimney damage, tree branches broken
F-1: 73-112 mph, mobile homes pushed off foundation
or overturned
F-2: 113-157 mph, considerable damage, mobile homes
demolished, trees uprooted
F-3: 158-205 mph, roofs and walls torn down, trains
overturned, cars thrown
F-4: 207-260 mph, well-constructed walls leveled
F-5: 261-318 mph, homes lifted off foundation and
carried considerable distances, autos thrown as far as
100 meters
Destroyed in Seconds- Monster Tornado - YouTube
Crazy visuals
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Tornadoes from Below and Above - YouTube
F5 Tornado in Elie, Manitoba on June 22nd,
2007 - YouTube
YouTube - F5 Tornado in Elie, MB Devastates
Part of Town & F3 Tornado in Oakville, MB
Tornado at soccer game! - /football – YouTube
http://past.theweathernetwork.com/news/storm
_watch_stories3&stormfile=Edmonton_tornado_
remembered_29_07_2012
The Wizard of Oz: Cyclone Clip - YouTube
Waterspouts
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Generally, waterspouts are given the honor of being called a "tornado over
water". But waterspouts are not truly given the name of a real tornado until
they reach land.
The Two Types of Waterspouts
Water spouts can start as tornadoes over land. If they move over a body of
water, they are classified as tornadic. This type of waterspout can be fairly
destructive. The second type of waterspout is formed over water initially
due to warm temperatures in the lower atmosphere along with high
humidity. Fair weather waterspouts are generally not as dangerous and are
more common than tornadic waterspouts. However, boaters and people
who live near larger bodies of water should take waterspout warnings and
watches very seriously
What are Waterspouts?
Amazing waterspout 'tornado' caught on camera off Australia – YouTube
Huge Water spout/Tornado on the water – YouTube
Twin Water Spouts Caught On Video - YouTube