Hurricanes!
Where Do They Form?—Fig. 11-3
Profile of a Hurricane
Profile of a Hurricane
- Form between __ and __
degrees latitude
- Asia--typhoons; India--_________;
Australia--______________
- Only fraction of tropical
disturbances become ___________
Profile of a Hurricane
- Hurricane--sustained winds
of at least ___ mph and rotary circulation
- diameters range from 100 km
to 1500 km; mature hurricane averages ____ km
- pressure ______ from outer
edge to center
- stronger pressure gradient
means _________ winds
Profile of a Hurricane—Figs. 11-4 and 11-5
Profile of a Hurricane--See Fig. 11-5
- Air moves from high to low
pressure-->air spirals inward toward center of hurricane
- Winds increase closer to center
(conservation of angular momentum: Box 11-1)
Profile of a Hurricane--See Fig. 11-5
- Eye wall: intense convection
surrounding center--fastest wind speeds and heaviest rainfall
- Eye: zone in center where precip ceases and winds subside, but still some clouds
- Eye offers deceptive break
(See Fig. 11-6)
Profile of a Hurricane—Fig. 11-6
Hurricane Formation
- Heat engine fueled by large
amounts of latent heat release
- Latent heat--heat released
into environment when water vapor __________
- Release of latent heat ______
air, which induces _____ buoyancy and ______________
- ________ pressure near
surface--encourages _____ rapid inflow of air
Hurricane Formation
- To get engine started, need ______
quantity of warm, moist air
- To keep engine going, need
____________ supply
- Ocean waters need to be at
least ___ ºF
- Need enough spin (________
_____) to generate rotary motion
Hurricane Formation
- ______ are tropical
disturbances
- Tropical disturbances often
form from easterly ______
- Easterly ______ gradually
move from _____ __ _____
Hurricane Formation—Fig. 11-8
Hurricane Formation—Fig. 3-7
Hurricane Formation
- Few disturbances become more
intense and organized systems
- Further development can be
inhibited by trade wind inversions or strong upper-level winds (vertical
wind shear)
- Trade wind inversion--temp
inversion that inhibits upward motion
- Wind shear disperses
essential heat away
Hurricane Formation
- Once circulation develops,
the tropical disturbance can be named a tropical ___________ (____)
- Move up to tropical ______
(____) if sustained winds are between 37 and ___ mph
- Move up to ___________ for
higher winds
Hurricane Formation
- The storm is given a name
(e.g. Andrew) once reaching ____ status and keeps the same name when it
becomes a __________ (Box
11-2)
- Annually between 80 and 100
______ develop around the world, but only around _____ become
_____________
Hurricane Decay
- Hurricanes diminish in
intensity if they:
- move over ocean waters that
are too cool
- move onto land
- move into area of
unfavorable upper level flow
Hurricane Decay
- Moving onto _____ causes
______ demise of hurricane
- Source of warm, moist air is
____ ____
- Increased surface roughness
__________ wind speeds
- Air flows _____ directly
from high to low pressure instead of _________ around Low
- Low then _____ __
Hurricane Destruction
- Saffir-Simpson
Scale--Table 11-2
- Cat 1: 74-95 mph; Minimal
- Cat 2: 96-_____; Moderate
- Cat 3: _____-_____; Extensive
- Cat 4: _____-155; Extreme
- Cat 5: > 155; Catastrophic
Hurricane Destruction
- Three hurricanes have been
Cat 5 when striking the U.S.:
Labor Day, 1935; Camille, 1969; Andrew, 1992
- Damage caused by hurricanes
is divided into three classes
- ______ ______
- Wind Damage
- _______ Freshwater _________
Storm Surge
- Storm surge: dome of water
___ to ___ miles wide that sweeps across the coast near where ____ makes
landfall
- _____ devastating damage of
________ zone
- ___% of all hurricane deaths
Storm Surge—Figs. 11-9, 11-11
Storm Surge--See Fig. 11-11
- Caused by strong onshore
winds piling up ocean water and churning up violent wave activity
- Most intense where winds
blowing onshore (right side of eye)
- Forward movement of
hurricane also contributes
Wind Damage
- Can cause ______ _____ of
some structures
- ______ homes particularly
vulnerable
- Flying debris
- Usually not as catastrophic
as ______________, but covers ______ area
- _________ may form also
Inland Flooding
- Torrential rains with
system
- Storm surge and strong
winds concentrated near coast, but heavy rains may affect places farther
_______ for several _____ after landfall
- Worst flooding often occurs
long after winds have diminished below __________ levels
- Inland flooding damage
____________ ________ that of storm surge
Detecting and Tracking
- Hurricanes’ __________ paths
make prediction difficult
- Locations a day’s striking
distance away could experience _____ skies and _____ winds
- ____________ time to prepare
- Now we have __________, aircraft,
______, and buoys to increase prep time
Satellites—Fig. 11-13 (b)
Satellites
- _________ single
advancement in tools for observing tropical cyclones
- Conventional observations
are limited in the open ______, but satellites can see what’s happening
there
- Storms monitored from their
____________, well before imminent danger of _________
Satellites
- Good for __________ and
monitoring
- But wind speed and
__________ estimates can have significant ______
- ___________ not great
enough to capture detailed ___________ characteristics
Aircraft Reconnaissance
- Can fly directly into storm
and measure details of its _________ and development
- Improves understanding of
__________ and characteristics of the storms
- Present level of
forecasting _________ would not be possible without these planes
Radar
- Help improve ___________
forecasts as storms approach coasts/move _______
- Doppler provides additional
info about _____ fields; helps detect ___________
- Improves rainfall and ______
forecasts
Data Buoys
- Buoys: remote _________
instrument packages in ______ locations along _______
- Only means of nearly
____________ ocean condition measurements