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Question:
How do clouds form?
Question:
What is freezing rain?
Question:
What is sleet?
Question:
How does snow form?
Question:
Why is there more snow early in the winter adjacent to the Great Lakes?
Question:
How do clouds form?
Answer:
As warmer air pass
over the ocean or large open lakes, the air picks up water vapour. As
the air warms, it rises because warm air is less dense than cold air.
As the warm air rises, the air cools and the water vapour in the air
condenses to form clouds of water droplets.
Clouds that form
at the surface of the Earth are known as fog.
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Question:
What is freezing rain?
Answer:
When the air
temperature is very cold, water vapour in clouds may fall as sleet,
hail, or snow. Water droplets in the clouds get cold, but may not
freeze. Under certain circumstances, the temperature of the water
droplet may drop below the freezing temperature of water, but the
water remains in the liquid state. This water is super-cooled. When super-cooled
water falls to the surface of the Earth, the water freezes instantly
on any surface it hits. This is called freezing rain.
Freezing rain may
cause lots of damage. Trees and power lines may break under the
weight of the heavy ice. Cities may have to go without electricity
when major power lines are broken.
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Question:
What is sleet?
Answer:
When the air
temperature is very cold, water vapour in clouds may fall as sleet,
hail, or snow. Water droplets in the clouds get cold, but may not
freeze completely. Sleet forms when partially frozen water droplets,
or rainwater, in the clouds falls and freezes completely when it hits
the surface of the Earth.
Like freezing
rain, sleet may be dangerous because it coats roads and sidewalks
with ice. Cars may not be able to stop on the slippery roads and many
collisions between cars may occur. Slippery sidewalks are very
difficult to walk along.
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Question:
How does snow form?
Answer:
High up in the
atmosphere, the air temperature is very cold. The water vapour may
fall as rain if the water does not freeze. However, if the air
temperature is so cold that the water droplets freeze, tiny ice
crystals form in the clouds. These ice crystals collide with each
other in the clouds or grow delicate shapes. The ice crystals combine
to form snowflakes. There may be hundreds of tiny ice crystals in a
single snow flake. These snow flakes fall from the clouds to form
snow on the ground.
If the air
temperature is not too cold and the air is very moist, the snow
flakes may grow into very large flake up to 1 or 2 centimetres across.
Every snow flake
is different. However, each snow flake has 6 sides.
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Question:
Why are there heavy snow-falls early in the winter adjacent to the
Great Lakes?
Answer:
In Ontario, land
adjacent to the Great Lakes often receive lots of snow in the early
part of the winter before the lakes freeze. Winds blowing over the
open water pick up extra water moisture because the unfrozen lakes
are warmer than the surrounding land. When the warm, moist air blows
off the warmer lakes and over the cold land beside the lake, the air
gets much colder. As the air cools, the water vapour condenses to
form water droplets and then tiny ice crystals. Those ice crystals
collide to form snow flakes.
The snow storms
formed this way are very local and are called snow squalls. In
Ontario, communities, such as Parry Sound, Barrie, Bracebridge, and
Sault Ste. Marie lie in the path of the winds that blow off the
unfrozen lakes. That is why these communities receive so much snow in
the early part of winter.
Once the Great
Lakes freeze, the snow squalls stop.
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