WHAT IS THE
ENVIRONMENTAL IMPACT?
ALBERTA’S TOP 10
COSTLIEST HAIL STORMS
Location
Date
Estimated Damage
Calgary
September 1991
Calgary
August 2012
500
Calgary
July 2010
400
Edmonton
July 1987
317
Calgary
July 1996
139
Calgary
July 1996
119
Calgary
July 1995
102
Calgary
July 1998
86
Red Deer
July 1991
59
Calgary
July 1992
55
In millions of dollars, and
normalized to 2011 dollars
1,281
Source: Public Safety Canada - Canadian Disaster Database
(http://cdd.publicsafety.gc.ca/)
Radar Station
WHICH AREAS ARE
PROTECTED?
Thunderstorms are seeded as they develop along
the foothills from the west of High River, all the
way to Rocky Mountain House, AB. The seeding
aircraft follow the bigger storms as they move off
the foothills and threaten communities. Priority is
assigned to storms depending on their severity
and the size of the community. Only those storms
threatening populated areas are seeded.
Seeding thunderstorms does not present
any environmental or health hazards
because silver iodide is a non-toxic
chemical at the concentrations used in
cloud seeding. Silver is actually already
present in Canadian soil and many of our
foods; it is also naturally found in our water
supplies.
In fact, the amount of silver iodide used
for cloud seeding is minimal compared to
the large quantities of water that storms
produce. Average seeding rates are about
10 grams per minute, which would be
equivalent to putting a spoonful of silver
iodide over the Niagara Falls every minute.
Rain samples collected from seeded
Alberta storms have been found to contain
levels of silver similar to most surface and
tap water supplies, and much less than
what would be present in a cup of water
stirred with a silver teaspoon.
FOR FURTHER INFORMATION
CONTACT:
Dr. Terry Krauss
Project Director
[email protected]
Todd Klapak
President
[email protected]
Alberta Severe Weather Management Society
c/o
128 Chancery Point
Sherwood Park, Alberta
T8H 1Z4
Severe Storm Rolling In
ALBERTA SEVERE
WEATHER
MANAGEMENT
SOCIETY
HAIL SUPPRESSION
2
1
Aircraft seed clouds with
silver iodide particles
3
Silver iodide particles cause
cloud moisture to freeze
and create ice crystals
Ice crystals grow and
fall as rain/snow
ALBERTA HAIL STORMS:
THE BREAKDOWN
In the months of June, July and
August, thunderstorms occur on
55-75% of days.
• Of these days, hail falls 50% of
the time
• 15% of the time that it hails,
hailstones will be greater than
the size of a walnut
• Rainfall has been observed to
increase minimally due to
cloud seeding
DID YOU KNOW?
Over 40 major hail
storms rumble through
Alberta every summer.
Over the past decade,
these hail storms have
caused over $1 billion
in damage.
WHO ARE WE?
HOW DOES IT WORK?
HOW IS IT CONDUCTED?
WHO BENEFITS?
The Alberta Severe Weather Management
Society (ASWMS) is a private, non-profit
organization that was established by the
Property and Casualty insurance companies
of Alberta to administer the cloud seeding
program. The actual cloud seeding operations
are outsourced and performed under contract
by Weather Modification Inc. (WMI), a private
atmospheric and cloud seeding company based
in Fargo, North Dakota.
Hail suppression works by seeding
thunderstorms with billions of microscopic
silver iodide particles. These particles act as
artificial ice nuclei which freeze the supercooled
water drops in the storm’s updraft.
Cloud seeding is conducted with five twinengine, high performance aircraft equipped to
dispense silver iodide. Three seeding aircraft
are stationed at Springbank Airport and two
are stationed at Red Deer Airport. Every year
from June 1st through to September 15th, these
aircraft remain on stand-by for immediate
launch to seed storms.
Cloud seeding has been found to reduce the
size/frequency of hailstones, which in turn
reduces damage to people’s gardens, crops,
homes, cars and businesses.
IS HAIL ELIMINATED?
For these reasons, a hail suppression program
makes good economic sense for everyone.
WHAT IS CLOUD SEEDING?
Cloud seeding is a form of intentional weather
modification that involves the process of
dispersing a particular substance (we use silver
iodide) into developing clouds. The intention is
to alter the cloud’s micro-physical properties
which results in a change of the type of
precipitation that will fall.
Seeding results in the formation of billions of
additional ice crystals that compete for excess
cloud water, thus producing smaller ice particles.
Many of these ice crystals melt completely as
they fall through warmer subcloud air on their
way down, but even those that don’t are still
significantly smaller than the “bruisers” that
smash windows, dent cars, and wreck roofs
and siding.
Cloud seeding also helps to control insurance
company losses, which in turn helps to stabilize
insurance rates throughout the province.
No, cloud seeding does not eliminate hail, but it
does reduce the size of hailstones which results
in less damage.
Cloud Seeding Aircraft