Grade 9 Academic Geography – Strand 3 Lesson 13
Factors Affecting Canada’s Climate
1.
Making Connections Pages 56-65
Mountains – Altitude
 Higher you climb, colder it becomes
 Impacts precipitation – Air rises to get over the mountain. The air cools, condenses and
falls back to earth as rain or snow on the windward side of the mountain. On the
leeward side it is dry.
2.
Ocean Currents
 A warm ocean current (1) brings moisture and (2) warms the nearby land (e.g., Pacific
Ocean off B.C.).
 Cool ocean currents (1) cannot hold as much moisture and (2) cool the nearby land (e.g.,
Atlantic Ocean off Labrador).
3.
Wind Direction and Presence of Large Bodies of Water
 Air over water collects moisture. Over land, the air rises and cools, and the moisture
falls back to earth as rain or snow.
 Water warms and cools slower than nearby land. In the summer, water is cooler than
the land and the air temperature over the water is also cooler. The cool air cools the
nearby land. The water has a moderating effect on land temperature.
 Canada’s prevailing wind is from the west.
4.
Latitude
 The further north from the equator, the colder it becomes. In the north, the sun’s rays
strike a very large area of the earth’s surface. The rays are not very intense, and thus,
the land is not warmed as much as at the equator.
There are four main factors that determine Canada’s climate:
 Mountain ranges and altitude
 Ocean currents
 Wind direction and the position of large bodies of water
 Latitude
Mountain Ranges and Altitude
The higher you climb (…or the higher the altitude…), the colder the air temperature becomes.
Mountains also effect precipitation. More rain and snow fall
on the windward side of the mountain (…the side facing the
oncoming winds). The leeward side or “rain shadow” is drier.
On the windward side, the air rises and cools as it travels up
the side of the mountain. As the air cools, it condenses and
moisture falls back to earth as rain or snow. On the leeward
side, the air is dry. As a result, there is little precipitation on
the leeward side.
Ocean Currents
The ocean currents in the Pacific Ocean off British Columbia are warm. Warm air brings moisture and also
warms the nearby land.
Ocean currents in the Atlantic Ocean along Labrador are cool. Cooler air
does not hold as much moisture as warm air. The cool air also keeps the
nearby land cool.
Wind Direction and Presence of Large Water Bodies
Air over a body of water collects water (i.e., evaporation). The wind carries
the moisture over the land, where the moisture may fall as rain or snow.
Water also cools and warms slower than nearby land. In the summer, the
water is cooler than the nearby land. The air temperature over the lake is
also cooler. As the cool air mover onto the land, it cools the land. In other
words, the large body of water has a moderating impact on the adjacent
land.
Latitude
The equator is 0O. The further north or south from the equator you go, the colder it becomes. The most
southerly point of Canada is about 41oN near Point Pelee in Lake Ontario. Most of Canada is north of
49oN. It is a long way north of the equator, and
thus, it is cool.
The colder northern latitudes are due to the angle
at which the sun’s rays strike the Earth. The sun’s
rays strike the equator in a very concentrated
area, and thus, the rays only heat a small area of
the Earth’s surface. The heat energy from the sun
is very intense at the equator. In contrast, the
sun’s rays at higher latitudes strike the Earth in a
very spread out area…due, in part, to the Angle of Incidence (about 23O). Since the same amount of
energy in the sun’s rays must heat a larger area, the area is cooler.
Angle of Sun’s Rays
The rays of the sun at mid-day are more concentrated
than is the case in early morning, or in the later
afternoon. It is warmer at midday for this reason.
When the sun's rays strikes the earth obliquely their
energy is disseminated over a wider area and does not
warm our section of the globe as do the more direct
summer rays. The same reasoning applies in the
variation of temperature during the day. As the sun
rises over the eastern horizon its rays strikes the earth
at an angle. As it rises higher in the heavens the rays become more concentrated until at mid day they
strike with their greatest force--their energy being concentrated in a comparatively smaller area. Then as
the sun sinks into the west, the rays gradually become less concentrated and intense, and it becomes
cooler again.
Practice
 On Page 61, answer Questions #1-3, 4(b-d)
 On Page 62-63, complete activity Reading Climate Graphs
 On Page 64-65, answer Question #2,3