2.4 WATER AND CLIMATE
(Page 366-370)
LEARNING OUTCOME 2: Investigate and interpret linkages among landforms,
water and climate
2E: describe the movement of ocean currents and its impact on regional climates
Climate is defined as: ___________________________________________________________
_________________________________________________________________________________
QUESTION: Is the climate of a region affected by surrounding water?
Use the information sheets to answer the following questions.
1. Locate Nanaimo, B.C. and Lethbridge, Ab. on the map. Record their longitude and
latitude and describe their surroundings (land, water, mountains, etc.)
CITY
LONGITUDE/
LATITUDE
SURROUNDINGS
LETHBRIDGE
NANAIMO
2. Compare the average temperatures and precipitation for the two cities.
CITY
LETHBRIDGE
NANAIMO
TEMPERATURE
PRECIPITATION
3. Knowing that both cities are located on the same latitude, thus being the same
distance from the equator, which of the two cities has the warmest climate?
4. Read page 367 and the factors affecting climate (on information sheet). Reason
out why the one city has a warmer climate?
I FOUND THAT large bodies of water (oceans or lakes) influence weather and climate
in their region BECAUSE water has a high heat capacity meaning it takes a lot of
energy to heat up and it releases a lot of energy (heat) as it cools. This keeps the
weather/climate warmer and more humid in the winter time. There is not much
difference between the daytime high and night time low.
CLIMATE INFORMATION SHEET
Nanaimo
The city of Lethbridge is located at 49.7° north latitude and 112.833° west longitude
and covers an area of 127.19 square kilometres
Nanaimo, British Columbia, is located on the southwest coast of British Columbia.
On Vancouver Island, Nanaimo lies on the Strait of Georgia, across from the city of
Vancouver. With a population of 70,130, Nanaimo is the second largest city on
Vancouver Island, and is just approximately 111km. north of the city of
Victoria. Located at 49°north, 123°west, and with an elevation of thirty meters.
Nanaimo experiences a Maritme climate that is characterized by moderately warm
temperatures in summer and only moderately cool temperatures in winter, resulting
in a low temperature range of only 15.3°C. The climate is also characterized by
significant precipitation in winter and little precipitation in summer, resulting 1144.5
millimeters of annual precipitation.
AVERAGE TEMPERATURES (⁰c) FOR LETHBRIDGE, ALBERTA AND NAINAIMO BC
Lethbridge
Nanaimo
Low
High
Low
High
January
-14.2
-2.6
-0.8
6.2
February
-10.8
-1.1
0
8.2
March
-6.9
5.3
1.3
10.9
April
-1.0
12.2
3.4
14.1
May
4.4
18.0
6.7
17.8
June
9.0
22.6
9.7
20.5
July
10.9
25.9
11.8
24
August
10.3
25.3
11.7
24.2
September
5.3
19.6
8.6
20.9
October
0.6
14.3
4.8
14.6
November
-7.1
4.6
1.5
9.1
December
-12.5
-0.9
-0.4
6.1
Lethbridge Alberta Canada Annual
Precipitation Graph
Climate: Lethbridge has a semi-arid climate with an average maximum
temperature of 12.3 °C (54.1 °F) and an average minimum temperature of
−1.1 °C (30.0 °F). With precipitation averaging 365 mm (14.4 in)–386.3 mm
(15.2 in), and 264 dry days on average, Lethbridge is the eleventh driest city
in Canada.[16][17] Mean relative humidity hovers between 69–78% in the
morning throughout the year, but afternoon mean relative humidity is more
uneven, ranging from 34% in August to 64% in January.[18] On average,
Lethbridge has 116 days with wind speed of 40 km/h (24.9 mph) or higher,
ranking it as the second city in Canada for such weather.[16]
Its high elevation of 929 m (3,047.9 ft) and close proximity to the Rocky Mountains
provides Lethbridge with cooler summers than other locations in the Canadian
Prairies.[19] These factors protect the city from strong northwest and southwest winds
and contribute to frequent chinook winds during the winter. Lethbridge winters have
the highest temperatures in the prairies, reducing the severity and duration of winter
cold periods and resulting in fewer days with snow cover.[20]
Factors affecting the climate of Nanaimo:
Temperature:
Latitude: Nanaimo has latitude of 49°N. Being so well into the northern part of the
world, the rays of the sun are at an extreme angle. This lowers the temperatures,
since we do not get the concentrated radiation from the sun.
Nearness to water: Vancouver Island is completely surrounded by water, the Pacific
Ocean. Since water cools down and warms up much slower than land, the ocean
tends to moderate the temperature, tending to keep the summers cooler and winters
less severe than other parts of Canada.
Air Masses: In winter, the Maritime Polar, a cold wet wind, which is milder than the
Artic air, yet cooler than the Tropic air, mainly affects Nanaimo. This air mass is
cold, but the coldness is lessened by the ocean effect described above. In summer,
the Continental Tropic that is relatively hot affects Nanaimo, however its impact on
temperature is lessened by the presence of the ocean.
Altitude and Landforms have no significant impact on the temperature of Nanaimo.
Precipitation:
Nearness to water: Situated as an island, surrounded completely by the Pacific
Ocean, the winds affecting the area are influenced by the ocean, therefore carrying
large amounts of moisture accounting for the high level of precipitation.
Landforms: Because of the Coast Mountains on the west coast of British Columbia,
Nanaimo experiences Orographic precipitation. This occurs when air is forced to rise
over an elevated landform. Therefore, as air masses pass over these mountains,
precipitation is dropped on what is called the windward side, Vancouver Island. The
opposite effect occurs summer time when the prevailing winds come from the east.
Air Masses: In winter, Nanaimo is mainly affected by a cold, wet air mass, the
Maritime Polar. This is what creates so much precipitation in the winter months. In
summer, this area is affected by a warm, moist air mass, the Continental Tropic.
Since this air mass originates quite a distance from Nanaimo, and the mountains
most of its moisture has been dropped before it reaches this area, resulting in low
precipitation in summer.
Altitude and Latitude have no significant impact on the precipitation of Nanaimo.
CURRENTS: read page 369-370
1. If two places at the same latitude on the same ocean you would think they had the
same climate—not necessarily! Fill in the chart.
PLACE
Climate
LABRADOR
SCOTLAND
2. Currents are: _____________________________________________________________.
3. Currents are caused by _______________, ___________________________________,
________________________________________ and __________________________________.
4. Diagram the three main currents in the North Atlantic Ocean. (page 369) Use
different colors and name them.
a. The Gulf Stream comes from (starts) an area that has what type of weather?
b. The Gulf Stream ends up in Scotland. How do you think the Gulf Stream
affects Scotland’s weather/climate?
c. What current travels by Labrador? Do you think it carries warm or cold air?
d. How does the winds from the North Pacific Ocean affect British Columbia’s
weather? Page 370
e. How does the cold Peruvian current affect Chile and Peru climate/weather?
5. What do you know about “El Nino and “La Nina”?