Transcript Ice storms/Hail What Are Ice Storms?

Ice storms/Hail
What Are Ice Storms?
Ice storms are when the fall of freezing rain persists for
a long period of time, and accumulates on roads, trees and
anything else that gets in it’s path. Ice storms typically
begin with snow. The snow changes briefly to sleet and
then to rain that freezes on impact, coating all exposed
surfaces with a growing layer of ice.
How Is An Ice Storm Formed?
Before the warm front of an ice storm,
warm, moist air moving in from the warm sector
overruns the surface cold air ahead to produce a
vertical temperature layering of the pre-warm
front atmosphere.
As this air rises over the cold air, it cools
and its vapour begins to condense. The clouds rise,
the temperature drops below freezing, and most
of its condensing vapour forms into ice crystals.
Formation Of An Ice Storm
Cloud vapor condenses,
and releases snow. The
snow melts into rain
when it meets a warm
air front. The rain
continues to fall, until
it hits the next cold
layer. The rain droplets
refreeze, or supercool,
and form freezing rain
and /or ice pellets.
How Large Are Ice Storms?
Ice storms lasting 12 hours or more generally
produce ice accumulations several centimetres thick and
affect an area that may range from a few kilometres to
areas covering several states/provinces.
The typical ice storm is 50 km wide and 500 km
long. Ice storms generally attract major headlines only
one in three years.
Seasons Ice Storms Occur
Residents of the eastern United States and Canada
may have freezing rain any time between late October
and early May. Storm systems that produce freezing
rain usually move across eastern North America from
the southwest bringing warm air from the Gulf of
Mexico and collides with the cold Arctic air of a highpressure system to the north.
Storm of ‘98
People in Montreal struggled for more than 30 days
with no electricity and no hot water while the temperature
outside dropped to –30 C. Jan. 5, 1998, as freezing rain
started to fall. It kept coming down for five days. At least
30 people died. On the darkest day, three million people –
roughly half of Quebec's population – were left without
electricity. Hundreds were trapped in their homes, waiting to
be rescued and thousands fled to shelters. The storm caused
an estimated $3 billion in damage.
Keep on Hand:
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Precautions
Emergency supply of foods that require no preparation.
Flashlights and a battery-powered radio with new
batteries.
Anti-freeze to protect pipes.
Simple fire-fighting equipment and tools.
Candles to provide light.
When the Power Goes Off:
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Turn off all electrical appliances.
Turn on battery powered radio for information.
keep doors and windows closed. houses will remain
warm for several hours.
Conserve fuel by warming only one room and keeping
temperatures low. Wear heavy clothing.
Check plumbing to ensure that water pipes are not frozen.
Impact On Wildlife
Animals outside in the winter must also cope with the effects of
an ice storm. Many animals starve when they are unable to reach
seeds, buds, or other food locked in the ice. Birds that can’t to
find shelter during the storm may have their feet frozen to a
branch or their wings covered in ice making them unable to fly.
Plants and animals, both wild and domestic, may be killed or
injured by ice build up. Power cables, tree branches and trunks
collect ice in large quantities.
Ice damages plants by sealing leaves, stems and buds from the
air, suffocating these parts. Also, ice sheets formed over snow
surfaces, may suffocate plants such as winter wheat.
Impact On Transportation
When transportation depended on foot power or
animals, moving along dirt roads, ice storms were
generally considered more annoying than hazardous,
except for those who travelled through wooded areas
where falling branches and trees were a danger.
Pavement and the automobile brought new travel
hazards to both drivers and pedestrians. On surfaces
such as road pavement and sidewalks, glaze ice forms a
smooth slippery surface. For drivers, the consequences of
ice storms can be serious, because stopping distances on
ice are twelve times greater than on dry pavement, and
double that on packed snow.
Insurance
Most insurance company's cover the costs
of rebuilding after an ice storm. If you have
the basic insurance package; property damaged
by branch’s or tree’s covered in ice, freezer
contents up to $1000, frozen pipes, and debris
removal costs are all covered by insurance.
However, damages to trees, shrubs or lawns, or
damages to electrical appliances are not
covered.
Tourism
Although ice storms are generally disliked by most of
the population, they provide weather watchers with
entertainment. Each look reveals new beauty. When
the ice clings to tree branches, and the sunshine
shines trough, it is an amazing sight!
How Is Hail Formed?
~Frozen precipitation in the form of lumps of ice, is
created when rain is forced above the freezing level by a
thunderstorm's updraft.
~Hail stones grow larger until they become too heavy to be
supported by the updraft and fall to earth.
Hail Formation
A hailstone the size of a golf ball needs over ten billion
super cooled droplets to be accumulated, and it must remain in
the storm cloud for 5 to 10 minutes and be held up by updrafts
over 88 km/h.
When sliced through their center, hailstones reveal an
onion-like layering, especially in the larger stones. These layers
alternate between opaque ice and clear ice, depending on how
quickly the hail stone freezes. The layers indicate how the ice
gathered during different stages of the hailstone's growth.
Hail Storm Formation
Hail Storm Effects
The most costly Canadian hailstorm occurred on
September 7 1991 in Calgary, Alberta causing an
estimated and $450 million in estimated total damage.
Hailstorms are among the most damaging weather events
each year in Canada. Costs are estimated at $100 million
per year in Canada.
Much of the damage from hail is on crops. Hail is
named the white plague by farmers. Damage to vehicles,
buildings, particularly roofs and landscaping are also
damaged during hail storms.
Positive points
Ice storms and hail can be beneficial. They can
knock down dead branches, releases seeds, and
provides nesting and sleeping shelters for birds and
animals.
Bibliography
http://haildata.atozad.net/
http://www.suite101.com/article.cfm/13646/86621
http://www.islandnet.com/~see/weather/elements/icestorm.htm
http://www.mthurricane.com/Pool%20Hail.mpg
www.rainhail.com/
http://www.weather.com/encyclopedia/winter/ice.html