Transcript Factors Affecting Climate - Gr 9 D

Chapter 12:
Climate Connections
What goes through your mind
when you think about
WEATHER
and
CLIMATE?
Something like this?
Or this?
Any of these?
Maybe even this!
WEATHER – is defined as day to day characteristics of the
atmospheric conditions – for example, a rainstorm, a
snowstorm, a hot sunny day, a windy day and so on…
CLIMATE – is defined as a long-term pattern of weather.
Climates influence many elements of our lives – for example,
where we live, what clothes we wear, and so on…
Canada’s climate has a great deal of variety because of four basic facts:
1) Canada extends for a great distance from north to south,
2) Different elevations produce different climate conditions,
3) Coastal regions have different climates from inland regions,
4) Wind and pressure systems move weather conditions from
one part of the country to another
Climate influences, and sometimes dictates, our daily
activities and travels. In the summer, it can be hot or stormy,
or it can be the perfect day for golf, baseball or going to the
beach. In the winter, it can be extremely cold with heavy
snowfalls and storms, which brings up travel concerns,
heating concerns, and of course, whether or not it will be a
snow day from school. When the weather is at extremes, we
are very aware of it and schedule our activities accordingly.
We can easily identify the climate and weather patterns that
affects our daily routines. BUT, what are the factors that affect
the type of climate that we experience?
L atitude
O cean Currents
W ind
E levation
R elief
N ear Water
Distance from the equator is a key factor in whether a
region is hot or cold.
The southernmost territory of Canada, is comprised of a
number of islands which form an archipelago in the Western
Basin of Lake Erie. Pelee Island and Middle Island are situated
just above the Canadian-American border at 41 degrees north
latitude. The annual average temperature is 9.1oC
Alert is the northernmost permanent settlement in the
world. It is located at 83 degrees north latitude, on the
north eastern tip of Ellesmere Island on the shore of the
Lincoln Sea, in the territory of Nunavut in Canada.
The
o
annual average temperature is –18.1 C
 The energy from the sun that hits the earth
closer to the equator covers a small area.
 The more 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 temperatures than those near
the equator because the same amount of energy
is spread over a larger area due to the curvature
of the earth.
* See figure 12-3 on page 129 in your text.
Climate is affected by ocean
currents – Figure 12-7 page 131.
The temperature of an ocean
current affects the temperature
of the air that passes over it,
making the air warmer or
colder.
A Few Examples:
West Coast: The warm North Pacific Current heats
the cool moist air which passes over it. This gives a
mild climate to the coastal regions of British
Columbia.
East Coast: The cold Labrador Current, which flows
southward from the Arctic, cools the air of coastal
locations in Labrador and northern Newfoundland.
What do you notice about the location of cold and
warm ocean currents in relation to the equator?
Ocean Currents Affecting North America
Air moves along the surface of the earth from highpressure areas toward low-pressure areas. It is the
moving air that causes wind.
It is the wind that moves air masses and therefore
causes weather.
In Canada, the prevailing winds are ‘westerlies’
beacuse they originate and blow towards the east.
Teperature decreases with an increase in
elevation.
Temperature drops at a rate of 1oC for every
100 meters of elevation (on average).
When the Dew Point (when water vapor
begins to condense) is reached, the rate of
cooling slows to 0.6oC per meters because as
water cools it realeases heat.
Relief refers to the differences in elevation
of the earth’s surface.
 Mountain ranges act as barriers to the
movement of air masses – therefore, for
example, Vancouver often has warm, rainy
weather in the winter and Calgary, on the
other side of the Cordillera, has very cold
dry weather.
Water has a moderating effect on land
temperatures.
Oceans and large lakes take a longer time to
heat up then the surrounding land mass and a
longer time to cool down.
 In summer, winds blowing over a body of
water will keep the surrounding land cooler
than it would be if the water body was not
present
 In winter, the water reatins heat and is
warmer than the surrounding land.
Winds blowing off a body of water warm
the surrounding land as a result.
From the Weather Network Website
www.theweathernetwork.com
More from the Weather Network
Website
Cold Front Symbol
Warm Front Symbol
Front:
A front can best be described as the border between two different air masses.
Cold Front:
A cold front is the leading edge of cooler or colder air. It cuts into the space that is
occupied by warmer air and eventually replaces it with a cooler/colder Air Mass.
This happens as the cold air causes the warm air to rise up and over it. As the warm
air travels upwards, it begins to mix with the cold air aloft and condenses to form
clouds. You can usually expect scattered showers and thunderstorms along the front
as it approaches.
Warm Front:
A warm front is the leading edge of a milder or warmer air mass. A warm front
travels in such a way that it results in warm air replacing colder air. This happens as
the warm air rises up and over the cold air below. As the warm air travels upwards, it
begins to mix with the cold air aloft and condenses to form clouds. You can usually
expect periods of rain or drizzle for many hours as the front approaches.
Air Pressure:(also known as atmospheric pressure)
Is the amount of force wielded on a surface by the weight of the air above it. The unit
for measuring air pressure worldwide is the kilopascal.
Low Pressure Centre:
Indicates an area of low atmospheric pressure. In a low, air is flowing counter
clockwise into the centre of the Low. The air will rise and cool often resulting in
clouds and precipitation.
High Pressure Centre:
Indicates an area of high pressure. In a high, air will slowly descend and flow out in a
clockwise direction at the ground. Normally a high will bring mainly sunny skies to
an area.
Jet Stream:
Moderately strong winds grouped in a narrow stream in the atmosphere, usually in
reference to horizontal, high altitude winds. The location and orientation of jet streams
change from one day to the next. Weather patterns (hot/cold, wet/dry) are influenced by
the position, strength and orientation of the jet stream (or jet streams).
Dewpoint:
The dewpoint is a measure of atmospheric moisture. It is the temperature at which air must
be cooled in order to reach saturation (assuming that air pressure and moisture content
are constant). As the surface of the earth cools at night, warm moist air near the ground is
chilled and water vapour in the air condenses into droplets on the grass and other objects.
Dew is particularly heavy on clear nights, when the earth cools rapidly. When a blanket of
cloud insulates the earth, the cooling rate is slower. The greater the difference between
the temperature and the dew point, the drier the air.
Frost Point:
The highest temperature at which atmospheric moisture will sublimate and form a deposit of
interlocking ice crystals on a cooled surface.
Using the Map of North
America provided for you,
draw, label and identify the air
masses and ocean currents
that affect Canada’s weather –
use figure 12-7 on page 131 in
your text book as a guide.
* Don’t forget to make a
legend and to add colour.
Complete questions:
# 1, 2, 3, and 4 a) –
Page 139 in your text.
* Write this down in
your agenda if you
have not done so
already.