Transcript File - Ms Hicks` Classes

Extreme Weather
Hottest Places
• Hottest Temperature on Earth = 56.7 °C in
Death Valley, California in 1913
• Hottest Temperature in Canada = 45.0°C in
Saskatchewan in 1937
Why is it so HOT in Death Valley?
• 4 mountain ranges lie between Death Valley
and the ocean, each one adding to an
increasingly drier rainshadow effect.
• The valley is a long, narrow basin 282 feet
below sea level, yet is walled by high, steep
mountain ranges. It is difficult for air to
circulate.
• The clear, dry air and sparse plant cover allow
sunlight to heat the desert surface. Heat
radiates back from the rocks and soil, then
becomes trapped in the valley's depths.
Coldest Places
• Coldest place on Earth = -89.2 °C at Vostok
Station in Antarctica
• Coldest place in Canada = -63.0°C in Snag,
Yukon in 1947
•
At that temperature, exposed skin would freeze in less than three minutes
What happens to boiling water when
it’s that cold out?
• https://www.youtube.com/watch?v=jKMNSvp
B9dY
• The hot water freezes -- changes from a liquid
to a solid -- as soon it comes into contact with
the cold air. That's why the water appears like
mist; it's no longer water but many tiny ice
crystals
Wettest Places
• Wettest place on Earth = Mawsynram, India
has an avg. annual rainfall of 467.35 inches
per year (about 39 feet)
• Wettest place in Canada = Moresby Island, BC
gets 6325 mm (20.8 feet) of rain a year
Driest Places
• Driest place on Earth = Dry Valleys, Antarctica
get literally no precipitation
• Driest place in Canada = Ashcroft, BC gets 8
inches of precipitation a year
Coldest: Snag,
Yukon
Wettest:
Moresby Island,
BC
Driest: Ashcroft, Hottest: Midale,
BC
Saskatchewan
Biggest Hail
• It was 47.3 cm big in South Dakota, USA in
2010
Damage Hail Can Do
How Does Hail Form?
• When thunderstorm
updrafts are strong
enough to carry water
droplets well above the
freezing level. This
freezing process forms a
hailstone, which can grow
as additional water freezes
onto it. Eventually, the
hailstone becomes too
heavy for the updrafts to
support it and it falls to
the ground.
Quebec Ice Storm of 1998
• Also called the North American Ice Storm or the Great
Ice Storm
• It was a massive combination of five smaller ice storms
which combined to strike a narrow strip of land from
eastern Ontario to southern Quebec to Nova Scotia
and Maine
• It caused massive damage to trees and electrical lines
all over the area, leading to widespread long-term
power outages.
• Millions were left in the dark for periods varying from
days to weeks, and in some instances, months.
• It led to 35 fatalities, a shutdown of activities in large
cities like Montreal and Ottawa
• 16,000 Canadian soldiers were deployed to help people
Did you know?
• Lightning strikes the CN Tower an average of 75
times per year. Long copper strips run down the
CN Tower to grounding rods buried below
ground to prevent damage.
How Does Lightning Form?
• Lighter, positively charged
particles form at the top
of the cloud. Heavier,
negatively charged
particles sink to the
bottom of the cloud.
• When the positive and
negative charges grow
large enough, a giant
spark occurs between the
two charges within the
cloud.
Thousands of Lightning Strikes
EVERY NIGHT
• One spot on the
Catatumbo River in
Venezuela has 40,000
lightning strikes every
night
• Local geological features
create a near constant
low-pressure area
• The longest it has ever
stopped was for a few
months
Tornadoes: What Are They?
• : a violently rotating
column of air extending
from a thunderstorm to
the ground
• Some have speeds of
250 mph or more
• They are caused when
warm, moist air from
the Gulf of Mexico
clashes with cold air
from the north
Tornadoes: Where Are They?
• There are tornadoes in Canada, mostly in the
Prairies and southwestern Ontario
• But they are bigger and much more frequent
in an area of the States called ‘Tornado Alley’
Warning Signs of a Tornado
• A dark, often greenish,
sky
• Wall clouds
• Large hail often in the
absence of rain
• The wind may suddenly
die down and the air
may become very still
• A loud roar similar to a
freight train may
be heard
Types of Tornadoes
1) Weak
• 69% of all
tornadoes
• Less than 5% of
tornado deaths
• They last 1-10
minutes
• Winds less than
110 mph
2) Strong
• 29% of all
tornadoes
• 30% of tornado
deaths
• May last 20
minutes or longer
• Winds 110-205
mph
3) Violent
• 2% of all
tornadoes
• 70% of all tornado
deaths
• They can last 1
hour
Tornado Rating System - The F-Scale
Scale
Wind Speed
(mph)
Damage
F0
40–72
Light damage. Some damage to chimneys; branches
broken off trees; some trees pushed over.
F1
73–112
Moderate damage. Roofs damaged, mobile homes
overturned; cars pushed off the roads.
F2
113–157
Significant damage. Roofs torn off, mobile homes
demolished; large trees snapped or uprooted; highrise
windows broken and blown in.
F3
158–206
Severe damage. Roofs & some walls torn off houses;
trains overturned; many trees uprooted; cars thrown.
F4
207–260
Devastating damage. Houses leveled; cars thrown and
large missiles generated.
F5
261–318
Incredible damage. Houses lifted off foundations and
carried off; car-sized missiles fly through the air, trees
debarked; steel reinforced concrete structures badly
damaged.
Worst Tornado
• There have only been
59 officially rated F5
tornadoes in the USA
and 1 in Canada
• There has never been
a F6 recorded storm
but there may have
been one in 1925
A tornado goes over top an
overpass
• https://www.youtube.com/watch?v=lHBZylcxI
vw
• This video was shot in 1991 and has become
famous
• It has actually lead to a few deaths because
people thought hiding under an underpass
was the best thing to do
• It actually makes the suction worse and will
suck people out
Deadliest Tornadoes
• Deadliest ever: approx. 1300 deaths in
Bangladesh in 1989
• Deadliest in North America: 695 deaths in
Missouri/Illinois/Indiana, USA in 1925 (it may
have been an F6 storm)
Waterspout
• A type of tornado formed over water
Dust Devils
• It is a strong whirlwind
• Dust devils are usually
harmless, but can on rare
occasions grow large
enough to pose a threat
• Dust devils form under
sunny conditions during
fair weather, rarely coming
close to the intensity of a
tornado
Fire Whirls
• Also known as a fire
tornado or fire devil, is a
rare phenomenon in which
fire forms a tornado-like
vortex of flames.
• Typically, they're made
from wildfires.
• Although it's rare, this type
of weather is extremely
dangerous. In 1923, a fire
whirl emerged during
Japan's Great Kanto
Earthquake and killed
thousands of people.
• https://www.youtube.com
/watch?v=UPj6yk2URuQ
Hurricanes: What Are They?
• They are also called cyclones and typhoons in different
parts of the world
• These huge rotating storms can be up to 600 miles
across and have strong winds of 75 to 200 mph.
• Each hurricane usually lasts for over a week, and start
over a warm part of the ocean
• Hurricanes rotate in a counter-clockwise direction
around an "eye" in the Northern Hemisphere and
clockwise direction in the Southern Hemisphere.
• The eye is the calmest part. It has only light winds and
fair weather.
• The Atlantic
hurricane season is
from June 1 to Nov
30, but most
hurricanes occur
during the fall
months.
• The Eastern Pacific
hurricane season is
from May 15 to Nov
30.
• Deadliest hurricane ever: 1970 Bhola Cyclone
hit Bangladesh and 300,000-500,000 people
died
• Typhoon Haiyan that just hit the Philippines in
2013 was one of the biggest ever
• Hurricane Katrina of 2005 was the third
deadliest hurricane in United States history,
killed at least 1500 people.
Weird Weather
Frost Quakes
• Also called cryoseisms.
• When the change from liquid to solid is rapid
(during a sharp temperature drop) and the
ground is saturated, it can cause explosions as
tension in the ground builds, until it cannot be
sustained.
• We heard them in Ontario in early 2014.
Ball Lightning
• Quite rare, a glowing
reddish ball of a few
cm to 30 cm in
diameter
• It may move up to 1
m/s horizontally with
a lifetime of a second
or two.
Volcanic Lightning
• Rock fragments, ash
and ice collide to
provide static charges
which then create
the conditions for
lightning to occur.
Animals Falling From the Sky
• Fish fell from the sky in
Australia, frogs rained down
on Hungary, worms fell in
Louisiana in 2007, and
spiders fell from the sky in
Brazil in early 2013.
• Some of these incidents
occur after tornadoes or
storms. Scientists have
hypothesized that the
creatures are picked up and
carried for several miles.
Coloured Rain
• Coloured rain has been falling on
the planet for centuries, and it
can occur in many coloures—
from reds and yellows to blacks
and milky whites.
• In 2001, there were reports of
coloured rains in southern India.
Scientists determined that
airborne spores from algae
caused these rains
• In Europe, red rains are typically
dyed by dust carried from
Saharan sandstorms. Pollens can
contribute to yellow rain, and
dusts from coal mines have been
known to cause black rain.
Moonbow
• A rainbow is caused by the Sun shining on
moisture droplets, most commonly in a postrain atmosphere. A moon bow is much rarer,
only seen at night when the moon is low and
full.
FogBow
Double Rainbow
Mirages
• Mirages occur when
light is refracted to
produce an image of
an object or the sky
where it is not. It is
most commonly seen
on hot surfaces, such
as the pavement or a
desert.
Haloes
• Like rainbows, haloes are
formed around the Sun
due to ice crystals being
refracted from the Sun’s
rays in the upper
atmosphere.
• Sometimes two or more
areas of the circle will be
brighter, forming what
are called Sun Dogs.
• Haloes can also form
around the Moon.
Sun Pillars
• Sun Pillars occur when
the setting sun reflects
off high, icy clouds at
different layers.
• It creates a pillar of light
that reaches high into
the sky. It is also
possible to see moon
pillars.
Belt of Venus
• The belt of Venus is a
phenomenon that
occurs during dusty
evenings when a
band of pinkish or
brownish sky will
appear between the
sky and the horizon.
Aurora Borealis
• Also known in the
southern hemisphere
as the Aurora Australis
• Charged particles from
the Sun that have
reached the Earth’s
upper atmosphere and
become excited.
• They are more
typically seen closer to
the poles
Green Flash
• Green flashes sometimes
occurs right after sunset
or right before sunrise.
• When the conditions are
right, a green spot is
visible above the upper
rim of the disk of the
sun.
• The green appearance
usually lasts for no more
than a second or two.
St Elmo’s Fire
• A luminous, and often audible, electric
discharge. Aircraft flying through active
electrical storms often develop corona
discharge streamers from antennas and
propellers, and even from the entire fuselage
and wing structure. It is seen also, during
stormy weather, emanating from the yards
and masts of ships at sea.