What is Weather?
The state of the atmosphere at any particular
place or time. Described using such
elements or variables as:
1. temperature
2. precipitation (type)
3. humidity
4. cloudiness
5. air pressure
6. wind speed and direction
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Elements of Weather
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 Always changing, exhibiting large
fluctuations in the atmosphere from
hour-to-hour or day-to-day
What is CLIMATE?
 climate is defined as an area's long-term
weather patterns. The simplest way to
describe climate is to look at average
temperature and precipitation over time.
Other useful elements for describing
climate include the type and the timing
of precipitation, amount of sunshine,
average wind speeds and directions,
number of days above freezing, weather
extremes, and local geography
What is CLIMATE?
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 Climate is the average
weather in a place over
many years. While the
weather can change in
just a few hours,
climate takes
hundreds, thousands,
even millions of years
to change.
Weather vs Climate
By aggregates of
weather statistics
over periods of
30 years
statistical data
precipitation, temp.
humidity, sunshine,
wind velocity
fog, frost, hail storms
over a period of time
Sunshine, rain
cloud cover,
winds, hail,
snow, sleet,
freezing rain
flooding, blizzards
ice storms, heat
Effects on Climate
Canada’s climate has so much variety because:
• It extends from a great distance from north
to south
• Different elevations
• Coastal and inland regions produce different
• Wind and pressure systems move weather
conditions from one part of the country to
• Some very large lakes, such as the Great
Lakes, also have an effect
Effects on Climate:
• The most southerly point in Canada is
Pelee Island in Lake Erie (41ºN)
• The most northerly point in Canada is
Alert (Ellesmere Island) (83ºN) latitude
• This large range in latitude has a major
impact on Canada’s climate
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Effects on Climate:
• distance from the equator is a key
factor in whether a region is hot or cold
• The size of the land mass in which a
region is located is also a factor
Effects on Climate:
• The energy from the sun
that hits the earth at the
equator covers a small
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• The same amount of
energy that hits the earth
at the northerly location is
spread over a larger area
because of the curvature
of the earth
• Places closer to the North
and South Poles
experience colder
Effects on Climate:
Relief and Elevation
• Relief refers to differences in
elevation of the earth’s
• Mountain ranges act as
barriers to the movement of
air masses
• This is why Vancouver often
has warm, rainy weather in
winter, while Calgary, on the
other side of the Cordillera,
has cold, dry weather
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Effects on Climate:
• If you were hiking to the top of a mountain,
you would notice that the temperature drops
steadily as you climb
• As the elevation gets higher, it gets colder
• As air rises, it expands because there is less
air pressure. As the air expands, it loses heat
Continental Environments
• Areas far from oceans and large lakes in
the interior of land masses have a
• The temperature range is great because
there is no large body to moderate the
hot temperatures of summer and the
cold temperatures of winter
Maritime Environments
• Coastal locations have a MARITIME
• The temperature range between the highest
average monthly temperature and the lowest
average monthly temperature is relatively
small and the level of precipitation is higher
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The Effect of Water
• Bodies of water have a moderating effect on
land temperatures
• Oceans and large lakes heat up and cool
down more slowly than land masses
• In summer, a body of water remains cooler
than the land surrounding it
• Winds blowing from over the water keep the
surrounding countryside cooler than it would
be if the water body was not present
The Effect of Water
• In winter, bodies of water retain their
heat and are warmer than the land
• Winds blowing off the water body warm
the surrounding countryside
• Therefore, maritime locations near a
large body of water, have cooler
summers and milder winters than
continental locations
Ocean Currents
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• Climate is affected by ocean currents
• The temperature of an ocean current affects
the tempeature of air that passes over it
• On the West Coast, the warm North Pacific
Furrent heats the cools, moist air which
passes over it
• This gives a mild climate to the coastal
regions of B.C.
Air Masses
• Air masses - a large volume of air with the
climate conditions of the area where it is formed
• Air masses originating from oceans contain
moisture. As the air passes over land, the
moisture is released in the form of precipitation
• Therefore, maritime locations are more likely to
receive more precipitation than inland
• On the other hand, air masses originating from a
continental climate will be dry
Winds and Pressure
• Air pressure - air that has weight
• Differences in air pressure are created
when the earth is heated to different
• Warmed air rising above the heated ground
creates an area of low pressure
• When the rising air has cooled, it falls
toward the earth and creates an area of
high pressure
Winds and Pressure
Heating of the
ground by the
sun warms the
air above it and
causes the air
to rise. This
produces a lowpressure area
The air cools
and sinks. This
produces a
Air at ground
level moves
from high
pressure to low
creating winds
Winds and Pressure
• Wind - moving air caused by the highpressure areas moving toward low-pressure
• Prevailing winds - high and low-pressure
belts that have created a pattern of winds.
a.k.a. “westerlies’. They move in air masses
that affect our weather
Winds and Pressure
• POLAR FRONT - the boundary between cold, dry
polar air and warm, moist tropical air
• Jet Stream - the current of fast-moving air located
high in the atmosphere above the polar front
• In the winter this boundary between cold and warm
air moves southward, allowing cold arctic air to flow
farther southward into the United States
• In the summer, it moves northward, allowing warm
air from the Gulf of Mexico to flow farther northward
in to Canada’s interior
• The warm air masses and the cold air masses that
meet at the polar front do not mix easily. Instead
they often enter into a battle in the sky that we see
as a storm
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