Ajman University

CHS College - Institute of Environment, Water and Energy

Science of Energy and Global Environment

Natural Hazards: Storms
Lecture Twenty Four
Storms
Contents
▪ Hydrologic Cycle
▪ Cloud-Forming Mechanism
• Movement of Weather Fronts
• Convection Currents
• Topographic Effect
▪ Tornados
▪ Hurricanes
▪ Ice Storms
• Climatic Causes
• Storm Effects
 Storms
Hurricanes
Hurricanes are intense cyclonic storms that develop over
the warm oceans of the tropics. These tropical storms go by
other names in the various parts of the world:
India/Australia - cyclones; western North Pacific -
typhoons; and the Philippines - baguio.
Surface atmospheric pressure in the center of a hurricane
tends to be extremely low. The lowest pressure reading
ever recorded for a hurricane is 870 millibars. However,
most storms have an average pressure of 950 millibars.
To be classified as a hurricane, sustained wind speeds must
be greater than 118 kilometers per hour at the storm's
center. Wind speed in a hurricane is directly related to the
surface pressure of the storm. The following graph shows
the relationship between surface pressure and sustained
wind speed for a number of tropical low pressure systems.
Storms

Relationship between surface pressure and wind speed for a

number of tropical low pressure systems. Tropical low pressure
systems are classified as hurricanes when their pressure is 980
millibars or lower, and sustained wind speeds are greater than
118 kilometers per hour.
Storms

Hurricane as seen from the space shuttle.

Storms

Satellite view of hurricane Floyd just before it made

landfall in North Carolina, September 15, 1999.
Storms

Hurricane Katrina – New Orleans

 Storms
Hurricanes measures on average 550 kilometers in
diameter. Mature hurricanes usually develop a cloud-free
eye at their center. In the eye, air is descending creating
clear skies. The eye of the hurricane may be 20 to 50
kilometers in diameter.
Surrounding the eye are bands of organized thunderstorm
clouds formed as warm air move in and up into the storm.
The strongest winds and heaviest precipitation are found in
the area next to the eye where a vertical wall of
thunderstorm clouds develops from the Earth's surface to
the top of the troposphere.
To form and develop hurricanes must be supplied with a
constant supply of warm humid air. Surface air with enough
energy to generate a hurricane only exists over oceans with
a temperature greater than 26.5° Celsius. Ocean
temperatures this high only occur in selected regions and
during particular seasons.
Storms

Typical areas where hurricanes begin their development and

the common paths of storm movement.
 Storms
Hurricanes dissipate when their energy supply is substantially
reduced. This occurs either with landfall or storm movement
into cooler seas. Most hurricanes live for about a week.
However, if a hurricane remains over warm water its life can be
extended. In 1992, hurricane Tina was an active tropical storm
for 24 days over the North Pacific.
Hurricanes are the most deadly and destructive type of severe
weather on our planet. One of the most destructive hurricanes
this century was Andrew in August of 1992. This storm, which
had a minimal pressure reading of 922 millibars, caused an
estimated 26 billion dollars worth of damage mainly in Dade
County, Florida.
The deadliest storm this century is probably hurricane Mitch
which hit Central America in late October and early November
1998. Estimates suggest that over 11,000 people died from this
storm. Most of these deaths were cause by flooding and
mudslides due to heavy rains.
Storms
The damage that hurricanes inflict is caused by high
wind speeds, heavy rainfall, storm surge and
tornadoes. High winds inflict damage by blowing down
objects, creating choppy waves and high seas, and by
inundating coastal areas with seawater.
Rainfall within a hurricane can often exceed 60
centimeters in a 24 hour period. If this rainfall occurs
on land, flooding normally occurs. A considerable
amount of damage can also occur because of hurricane
generated tornadoes. About 25% of the hurricanes
that make landfall have tornadoes.
Storms
Canada’s January 5th 1998, Ice Storms
The Ice Storm began on
January 5th 1998, and
lasted for five days, yet its
effects were considerable
for over a month. Areas
effected were located right
across Eastern Canada
and New England.
Canada’s largest province,
Quebec worst affected,
particularly Montreal.
Remembered as the worst
storm on record
particularly because of
long term power cuts.
Storms

Location of Quebec and Surrounding Regions hit by an ice

storm on January 5th, 1998.
Storms
Meteorological Causes
Pre-Cursor Conditions: High
pressure system over SW
Quebec sends cold air south,
low pressure system over
the Gulf of Mexico sends
warm, moist air North and
the two air masses meet
and cause a temperature
inversion.
Freezing Rain: Precipitation ‫املطر املتجمد‬
falls as super-cooled
droplets. As it falls through
the warm layer, it does not
have time to melt. As it
lands in the cold layer
below, it freezes on impact.
Storms

Anatomy of an ice storm.

Storms

The Iced blocked Port of Montreal.

Storms
Montreal
• Many roads blocked,
accidents and congestion.
• All residents without power
sent to rescue shelters.
• Primary remediation efforts
were to restore power and
remove ice / obstructions
from dangerous situations.
Effects of the Ice Storm on Power Utilities
• 2.5 Million people without power for longer than 3 days.
• Knock on effects for water, gas, cellular and phone
companies.
• Remaining power networks faced overload.
• Risk of retaining power to essential services such as
hospitals and government offices.
Storms

Various
examples of
congestion,
disruption,
power loss
and
emergency
rescue
around
Montreal.
Storms
Effects on Forestry of New England
• Large areas of New England
declared a Federal Disaster
Zone by the American
Government as eligible for
aid.
• Thousands of acres of forest
destroyed, economical
valuable for supplies of
Timber and Maple Syrup!
• Economic Impact on small
town communities
considerable, yet unlike
Canada, no major American
Cities were affected by the
Ice Storm.
Storms
Military Implications of the Ice Storm
• Largest Canadian Peacetime Operation own
territory.
• 16,000 troops called in, many from the United
States.
• Severe threat of looting and associated risks of state
of emergency enforcement.
• Operation seen as a rehearsal for the nationwide
power outages which could have occurred due the
Millennium Bug.
• Quebec’s reliance on Federal and American aid
during the Ice Storm may have damaged its
campaign for Independence.
Storms

Military Intervention
Storms
Conclusion
• Immense cost of damage to
property and the economy.
• Cause of deaths: Exposure,
poisoning from fuel burning
heaters, road accidents.
• Damaging to Quebec’s claim
for independence as heavily
reliant on Canada and the
US for military manpower,
healthcare and monitory
aid.
Storms
Tsunamis
Definition of Tsunami
A series of massive ocean waves with extremely long
wavelengths and periods, of average speed of 550 mph,
and height of 20 m.
Causes
•Volcanic eruptions.
•Submarine earthquakes.
•Meteorite impact.
•Submarine landslides.
Tsunami
Tsunami generation
• Sediment or rock displaced at ocean floor.
• Water rushes in from surrounding sea to restore the
water level.
• Sea level along nearby coast is lowered.
• Large waves travel outwards from zone of
displacement.

Prediction and modelling

• Importance of prediction: Saving lives, Monitoring
progression and development.
• National Oceanic and Atmospheric Administration
(NOAA) - two tsunami warning centres
Tsunami
Pacific Tsunami Warning Centre
• Facilities: Seismic studies, information from sites in
the Pacific, tidal gauge systems - record tsunami and
signature and wave heights.
• Aims: Detect and locate earthquakes, determine
tsunami generation and provide warnings.

Alaskan Tsunami Warning Centre

• 16 Seismic stations and 8 tidal gauge systems.
• Covers from Russia to South California.
• Sends out Warning/Watch Bulletin to endangered
coasts if tsunami detected.
Tsunami
Modelling tsunamis
• Difficulties involved: Shape of sea bed, nature of
coastlines, effect of backwash and headlands and
harbour walls.
• Powerful computer - based modelling.
• Lack of information - rare events.

Uses of modelling
• Warning Systems.
• Arrival times.
• Mapping areas at risk from inundation (TIME).
Tsunami

Modeling Tsunami.
Tsunami
Hypothetical Tsunami
along the Pacific
Northwest Coast
generated by
oblique slip.

Tsunami Model
Tsunami

Finite-Element Model Finite Difference Model

ADCIRC MOST
Tsunami
Occurrence of tsunamis
• Most prevalent in Earthquake
the Pacific region. location
• Susceptible
coastlines: Greater
than 25ft. Above
sea level and 1 mile
of shoreline.
• Hawaii – 1 major
event every 20-25
years.

Papua New Guinea 1998

• July 18th 1998.
• Complete devastation of 7 villages and 2,300 deaths
(230 children).
• Earthquake induced.
Tsunami

Distribution and Date of Tsunami Waves.

Tsunami
Tsunami generation
• Tsunami earthquake
- disproportionably
large effects. Why?
• Triggered seafloor
disturbance.
• Bathymetry.
Tsunami
Why Tsunami is Dangerous?
• Land encompassed by water.
• Poor quality housing.
• Remote location.
• Infrastructure hindered rescue attempts.
• No official warning system.
• Lack of education.
• No physical mitigation system.
• Lack of medical supplies and health training.
• Dwellings built close to sea level (1-3m).
• Buildings close to shoreline.
• No effective evacuation procedure.
• Few families had an Action Plan.
• Relief effort unable to reach victims.
• Many residents fled to forest.
Tsunami
Mitigating tsunami hazards
• American tsunami centres issue tsunami warnings
by: warning/watch bulletins - based on seismic
data, warning Bulletins - use tidal gauge
information issued by: Media, Weather Radio
system, Coast Guard, local authorities and
emergency managers.

• Satellite link warning: Japanese tsunami warning

system. Based accelerometers - triggered by quakes
over 7.0 on the Richter Scale. Satellites send
warnings to ground stations - action plan
commences. Response time of 1 minute - 98%
reliable.
Tsunami
Mitigating tsunami hazards
• Tsunami fact sheet: Produced by the Federal
Emergency Management Agency (FEMA).
Procedures to take before, during and after a
tsunami. Aimed at the general public and residents
living in vulnerable areas.

• Papua New Guinea – Recommendations: Annual

evacuation drills. Pine trees fronting coastal
communities. Coastal zoning - no building within
400m, severe risk <800m. No building on old site.
Education.
Sand Storms

One of sand storms near California. These storms are

responsible for transport of the loess sediments.
Sand Storms

Sand storms attacks cities, farms and lowers

the visibility.
Thank You