2. What is a Natural Disaster?
• Definition:
– The effect of a natural hazard, which leads
to financial, environmental or human losses
– Natural events that kill people or damage
property or the environment
3. List of Natural Disasters
• Following are the different weather
phenomena we are going to discuss:
–
–
–
–
–
Avalanche
Blizzard
Earthquake
Hailstorm
Hurricanes
–
–
–
–
–
–
Lightning
Tornado
Tsunami
Typhoon
Volcano
Wildfire
5. What is an Avalanche?
• Definition:
– When massive slabs of snow break loose from
a mountainside and shatter like broken glass
as they race downhill
• These moving masses can reach speeds of
80 miles (130 kilometers) per hour within
about five seconds.
6. • What causes Avalanche?
– A vibration or movement like the voice of
a person or a train
– Certain weather conditions like wind and
rain
– A rock or a piece of ice can shake the
snow to slide down the mountain
7. • Avalanches kill more than 150 people
worldwide each year
• Victims caught in these events seldom
escape
• Once the avalanche stops, it settles like
concrete. Bodily movement is nearly
impossible
9. What is a Blizzard?
• Definition:
– A severe snowstorm that usually has very
cold temperatures and high winds. These two
conditions create blowing snow
– A long-lasting snowstorm with very strong
winds and intense snowfall
10. • Blizzard Warning:
– Heavy snow and strong winds will produce
a blinding snow, near zero visibility, deep
drifts and life-threatening wind chill
• The blowing winds and low
temperature can cause frostbite
and/or hypothermia
13. What is an Earthquake?
• Definition:
– An earthquake is what happens when two blocks of
the earth suddenly slip past one another
• Fault plane The surface where the slip occurs
• Hypocenter The location below the earth’s
surface where the earthquake starts
• Epicenter The location directly above it on
the surface of the earth
14.
15. • The Plate Tectonic Theory
– The earth's crust and upper mantle is
composed of several large, thin, relatively
rigid plates that move relative to one
another
– The plates are all moving in different
directions and at different speeds.
– Sometimes the plates crash together or pull
apart. When this happens, it commonly
results in earthquakes
16. • Earthquakes can be felt over large areas
although they usually last less than one
minute
• How are earthquakes recorded?
– By instruments called seismographs
– The recording they make is called a
seismogram
17.
18. – When an earthquake causes the ground to
shake, the base of the seismograph shakes
too, but the hanging weight does not
– Instead the spring or string that it is
hanging from absorbs all the movement
– The difference in position between the
shaking part of the seismograph and the
motionless part is what is recorded
20. What is a Volcano?
• Definition:
– An opening, or rupture, in a planet's surface or crust,
which allows hot magma, volcanic ash and gases to
escape from below the surface
• Volcanoes are generally found where
– tectonic plates are diverging or converging
– there is stretching and thinning of the Earth's crust
in the interiors of plates
21.
22. • Volcanoes are found in three states
– An extinct volcano will never erupt again
– A dormant volcano has not erupted in 2000
years
– An active volcano has erupted recently and
is likely to erupt again
23. • Advantages of Volcano
– Many people rely on volcanoes for their
everyday survival.
– Geothermal energy can be harnessed by
using the steam from underground which
has been heated by the Earth's magma.
• Used to drive turbines in geothermal power
stations to produce electricity for domestic and
industrial use. Used in Iceland and New Zealand
24. • Tourist attraction: Millions of visitors
every year visit the volcano, hot springs
and geysers.
– Tourism creates many jobs for people like
in hotels, restaurants, gift shops and locals
can act as tour guides
• Lava contains minerals which can be
mined once it has cooled. These include
gold, silver, diamonds, copper and zinc
25. • Volcanic areas often contain some of
the most mineral rich soils in the world.
This is ideal for farming.
– These areas can be cultivated to produce
healthy crops and rich harvests
27. What is a Tsunami?
• Definition:
– A series of large ocean wave usually caused
by an underwater earthquake or a volcanic
explosion
• The waves may travel in the open sea as fast
as 450 miles per hour
• Tsunamis can reach the heights of over 100
feet (30.5 meters)
• They are NOT tidal waves
28. • Tidal waves are caused by the forces
of the moon, and planets upon the
tides, as well as the wind as it moves
over the water.
• Whereas a tsunami flows straight. This
is why they cause so much damage
31. What is a Tornado?
• Definition:
– A violent rotating column of air extending from a
thunderstorm to the ground
– Vertical funnels of rapidly spinning air
• Also known as Twister
• Wind speed: up to 300 mph
• Funnels width: up to 660 feet (200 meters)
32. • Tornadoes are formed when moist warm
air and cool dry air collide to create
unstable atmosphere
• This collision creates a shift in the wind
direction and speed
• However, tornadoes are still a mystery.
Scientists still are not very sure what
causes and finishes them
33. • Tornadoes can occur anywhere and any
time as long as the proper conditions
are there
• But the United States is a major hotspot
with about a thousand tornadoes every
year.
– "Tornado Alley," a region that includes
eastern South Dakota, Nebraska, Kansas,
Oklahoma, northern Texas, and eastern
Colorado, is home to the most powerful and
destructive of these storms.
35. What is a Tropical Cyclone?
• Definition:
– A storm system characterized by a large lowpressure center and numerous thunderstorms
that produce strong winds and heavy rain
• It is formed over oceans
36. • Tropical cyclones gather heat and
energy through contact with warm
ocean waters
– They form only over warm ocean waters
near the equator
• The warm, moist air over the ocean
surface rises upward
37. • Because this air moves up and away
from the surface, there is less air left
near the surface
• In other words, the warm air rises,
causing an area of lower air pressure
below
38. • Tropical cyclone a generic term
– Depending on its location, is referred to by
names:
• Hurricane
• Typhoon
• Cyclone
39.
40. What is a Hurricane?
• Definition:
– Only tropical cyclones that form over the
Atlantic Ocean or eastern Pacific Ocean are
called hurricanes
41. What is a Typhoon?
• Definition:
– Only tropical cyclones that form over the
western Pacific Ocean are called typhoons
42. What is a Cyclone?
• Definition:
– Only tropical cyclones that form over the
Indian Ocean areas are called cyclones
44. What is a Wildfire?
• Definition:
– Any uncontrolled fire often occurring in
wildland areas
• Also known as a wildland fire, forest fire,
vegetation fire, grass fire, or bush fire
• Speed: up to 23 kilometers an hour
45. • Consume everything—trees, brush, homes,
even humans—in its path
• Three conditions are needed for a wildfire to
burn, which firefighters refer to as the fire
triangle:
– Fuel any flammable material surrounding a fire
like trees, grass, houses etc
– Oxygen air supplies it
– Heat source help spark the wildfire and bring
fuel to temperatures hot enough to ignite.
Lightning, burning campfires or cigarettes, hot
winds, and the sun
46. • Wildfires can occur anywhere, but are
common in the forested, vegetated,
and grasslands areas
• Fires are particularly prevalent in the
summer and fall, and during droughts
when fallen branches, leaves, and
other material can dry out and become
highly flammable
47. How do firefighters put out the wildfires?
• Use a tool known as a pulaski, a
combination of an ax and hoe used to
dig a fireline.
– A fireline is a strip of land from which all brush
and debris have been cleared to rob a wildfire of
its fuel.
48. • Use hotshots and smoke jumpers to
clear a large path in a big circle around
the fire so the blaze is contained in a
ring of dirt.
– When the fire reaches this area, it runs
out of fuel and starves to death.
49. • If the fire is too large, however, planes
and helicopters fly overhead, dropping
water and special chemicals that
smother the flames. This pink, fireretardant chemical is called sky jell-o
52. What is a Hailstorm?
• Definition: Hail
– A form of solid precipitation in the form of
irregular lumps of clear ice and compact
snow
• Any thunderstorm which produces hail
that reaches the ground is known as a
hailstorm
53. • Conditions necessary for Hail formation:
–
–
–
–
Strong thunderstorms clouds
Strong motion of air
Large water droplets
A good portion of the cloud layer is below
freezing 0 °C
• Spherical in shape with a diameter up to 0.5
inch
– In rare cases, hailstones having diameters up to 6
inches have been observed
54.
55.
56. • Hail causes much damage to:
– Farmers’ crops
• Wheat, corn, soybeans, and tobacco are the
most sensitive crops to hail damage
– Livestock
– Humans
• Massive hails can cause concussions or fatal
head trauma
– Man-made structures
• Especially glass structures
– Airplanes and automobiles
57. • Methods of detecting hail-producing
thunderstorms
– Weather satellites
– Weather radar imagery
• Severe weather warnings are issued for
hail when the stones reach a damaging
size
59. What is a Lightning?
• Definition:
– A bright flash of electricity produced by a
thunderstorm
• All thunderstorms produce lightning and
are very dangerous
60. • Lightning kills and injures more people
each year than hurricanes or
tornadoes; between 75 to 100 people
61. • What causes Lightning?
– Lightning is an electric current.
– Within a thundercloud way up in the sky, many
small bits of ice (frozen raindrops) bump into each
other as they move around in the air.
– All of those collisions create an electric charge.
After a while, the whole cloud fills up with
electrical charges.
– The positive charges or protons form at the top of
the cloud and the negative charges or electrons
form at the bottom of the cloud.
62.
63. – Since opposites attract, that causes a
positive charge to build up on the ground
beneath the cloud.
– The grounds electrical charge concentrates
around anything that sticks up, such as
mountains, people, or single trees.
– The charge coming up from these points
eventually connects with a charge reaching
down from the clouds and - zap - lightning
strikes!
64.
65. • Types of lightning
– Cloud-to-Ground
– Intra-cloud
– Inter-cloud
• How hot is lightning?
– Lightning is approximately 54,000o
Fahrenheit. That is six times hotter than
the surface of the sun!
