Download Chapter 6 Climate

Chapter 6 Climate
Climate
 Canada's climate is not as cold all year
around as some may believe. In winter,
temperatures fall below freezing point
throughout most of Canada. But the southwestern coast has a relatively mild climate.
Along the Arctic Circle, mean temperatures
are below freezing for seven months a year.
Climate
 During the summer months the southern
provinces often experience high levels of
humidity and temperatures that can surpass
30 degrees Celsius regularly.
 Western and south-eastern Canada
experience high rainfall, but the Prairies are
dry with 250 mm to 500 mm of rain every
year.
Weather/Climate
 Weather
– Is the result of the day-to-day conditions of the
atmosphere.
 Climate
– A long term pattern of weather
– Climate Is The Weather + Weather + More
Weather
 Climate is what you expect, weather is what you get!
Weather
 Types of things given in a weather forecast:
– Temperature
– Humidity
– Cloud cover
Precipitation
Wind speed/direction
Air pressure
Climate
 Factors that affect climate (J.BLOWER);
– Jet Stream (air masses)
– Bodies of water
– Latitude
– Ocean Currents
– Winds
– Elevation
– Relief

Note: Different parts of Canada have different climates
.
Factors that affect Climate
A. Jet Stream (Air Masses)
Air Masses -- is a large body of air that
has similar temperature and moisture
properties throughout.
For example: Winds blowing from a cold region will bring
cold temperature conditions to an area over which they
pass
Factors that affect Climate
 B. Bodies of water
– Water warms up more slowly than land
and cools off more slowly
– As a result of this, land near bodies of
water are affected by the weather over
these bodies of water.
Factors that affect Climate
 Bodies of water
– The ocean make the temperature on land
cooler in summer and warmer in winter.
–This is called a maritime
climate.
Factors that affect Climate
 Bodies of water
– Continental Climate— Land in the
interiors are not influenced by the sea and
experience extremely cold winter and hot
summers. PG 63
This climate is characterized by winter temperatures cold
enough to support a fixed period of stable snow cover
each year, and relatively moderate precipitation
occurring mostly in summer,
Factors that affect Climate
C. Latitude
– Distance from the equator
 Angle at which sun rays strike the earth
 Length of daylight period
 The tilt of the earth’s axis combined with the
earth’s rotation in orbit around the sun
results in different day lengths.
Factors that affect Climate
D. Ocean Currents
– The movement of large quantities of ocean
water due to the unequal heating of the top
layer of the water by the sun.
– For countries on the east side of the Atlantic, winters are a
balmy holiday compared with the same latitudes on the west:
the frigid coasts of Newfoundland and Labrador.
Factors that affect Climate
 Ocean Currents
– There are warm ocean currents and cold ocean
currents. These currents affect the air above
them in two ways:
 Warming or cooling air masses
 Warm air absorbs moisture, cold air does not absorb
moisture.
Factors that affect Climate
E. WINDS
– Wind is the flow of air.
– Created by differences in air pressure
– Winds are also caused by temperature
differences
 Note: Differences in air pressure produce
convection currents and wind
Factors that affect Climate
 Prevailing Winds
– are the trends in speed and direction of wind
over a particular point on the earth's surface.
– Canada’s prevailing wind pattern blows from
west to east.
– Prevailing winds bring different types of weather
and are the causes of waves as they push the
ocean.
Factors that affect Climate
 Prevailing Winds
– The direction of wind is measured in terms
of where the air is coming from.
– A northerly wind blows air from north to
south. A southwesterly wind blows air from
the southwest to the northeast.
Factors that affect Climate
F. Elevation: the height above sea
level.
– Virtually anywhere that has a
high elevation will be colder than
lower elevations at the same
latitude.
– As air rises it expands because
there is less air pressure (cont.)
– As air expands it becomes less
dense and less dense air holds less
heat than dense air, so the farther
above sea level you are, the lower the
temperature will be.
– The rate of cooling varies according
to the moisture content of the air.
– When air has a relative humidity of
100%, condensation begins and this
affects the cooling rate.
Factors that affect Climate
Air pressure
Air at sea level is what we're used to, in
fact, we're so used to it that we forget we're
actually feeling air pressure all the time!
 Less air pressure at high altitudes than at
sea level.
 How much pressure are you under?
– Earth's atmosphere is pressing against each
square inch of you with a force of 1 kilogram per
square centimeter (14.7 pounds per square inch).
The force on 1,000 square centimeters (a little
larger than a square foot) is about a ton!
 Why doesn't all that pressure squash
me?
– Remember that you have air inside your body too,
that air balances out the pressure outside so you stay
nice and firm and not squishy.
Elevation
 When condensation is not occurring, an air
mass loses 1c0 for every 100 m it rises.
 When condensation is occurring, an air
mass loses 0.6c0 for every 100 m it rises.
 Diagram of air rising up a mountain
Factors that affect Climate
 G. Relief
–Refers to the difference in elevation
of the earths surface.
–Mountain ranges affect climate
because they act as barriers to the
movement of air masses.
Factors that affect Climate
 Relief
– Mountain barriers also tend to cause
precipitation to occur.
Factors that affect Climate
 Sea breezes
Factors that affect Climate
 Sea breezes
– During the day the land becomes warmer than
the sea.
– A low pressure system is created over the land
and a high pressure system is created over the
sea.
– Winds move from highs to lows
– Therefore the winds move from the cooler water
towards the land creating a sea breeze
Factors that affect Climate
 Land breeze
Factors that affect Climate
 Land breeze
– During the night the land cools faster than the
sea.
– A high pressure system is created over the land
and a low pressure system is created over the
sea.
– Winds move from highs to lows
– Therefore the winds move from the cooler land
towards the sea creating a land breeze
Types of Precipitation
 Precipitation
– is any product of the condensation of
atmospheric water vapor that is deposited on
the earth's surface.
 Precipitation that reaches the surface of the
earth can occur in many different forms,
including rain, freezing rain, drizzle, snow,
sleet, and hail.
Types of Precipitation
 1. Relief Precipitation (orographic)
 2. Convectional Precipitation
 3. Cyclonic/Frontal Precipitation
Relief Precipitation
 Occurs when an air mass is forced from a
low elevation to a higher elevation as it
moves over rising terrain
Relief Precipitation
 As the air mass rises it expands and cools.
 This cooler air cannot hold the moisture as
well as warm air can.
 When the dew point is reached the air
becomes saturated with water vapor and
condensation occurs, creating clouds and
frequent precipitation.
Relief Precipitation
 As the cool air descends on the leeward
slope of the mountain it gets warmer.
 Since warm air is able to hold more water
vapour than cooler air, the clouds
decapitates and the relative humidity drops
creating rain shadow conditions.
 Evaporation rather than condensation
occurs.
Relief Precipitation
Convectional Precipitation
 Develops as a result of uneven heating of
the earth’s surfaces by the sun.
 Air above this area becomes warmer than
the surrounding air and starts to rise
 This process creates convection currents or
updrafts
Convectional Precipitation
 The rising air expands and cools, and water
vapour condenses to form clouds
 Water droplets get larger and eventually the
weight forces them to fall.
 As the precipitation reaches the ground it
cool it and the air and stops more updrafts
from forming.
Convectional Precipitation
Cyclonic/Frontal Rainfall
 Warm Moisture laden air meets cold air;
 Warm air is less dense & is forced up over
the cooler, more dense air;
 Warm moisture laden air cools at higher
altitude;
 Cool air holds less moisture;
 Clouds condense and rain falls.
Cyclonic/Frontal Precipitation
 A Cyclonic storm is a large low pressure cell
that forms when a warm air mass and a cold
air mass collide.
 In Canada these low pressure storms move
from west to east at all times of the year.
Cyclonic/Frontal Precipitation
Interpreting Climate Graphs
What is a climate graph?
•a type of chart or graph that displays for a place the annual
pattern of the two most important climate variables:
precipitation and temperature
Temperature is
shown by the
line, with the
degrees on the
left Y-axis.
The data shown are
monthly averages,
with the months
across the X-axis.
Precipitation is
shown by the
bars, with the
amounts on the
right Y-axis.
Of what value are climate graphs?
•Climate graphs can be used to compare the climate of
selected locations quickly and simply.
•Especially useful to tell if a place has a continental or a
maritime climate.
•Continental: low annual precipitation; large annual
temperature range because of no moderating effect of a
large a body of water.
•Maritime: high annual precipitation; low annual
temperature range because of the moderating effect of
large a large body of water.
Low (fairly low) annual
temperature range.
Winters are mild.
Summers are not hot.
High annual precipitation,
with no seasonal
maximum.
Therefore, it’s a maritime
climate.
Moncton, NB
Low annual precipitation
High annual temperature
range
Therefore, continental climate.
Yellowknife, NWT
Fairly low annual
precipitation
Large annual temperature
range
Therefore, continental
climate
Timmins, ON
Very low annual
precipitation
Large annual temperature
range
Therefore, continental
climate
Resolute, NWT
Very low annual
precipitation
Large annual temperature
range
Therefore, continental
climate
Wait a minute …..!
Resolute is on water yet it
has a continental climate.
How come?
Because the water it is on
(the Arctic Ocean) is frozen
9 months of the year and so
acts like a land area.
Resolute, NWT
Fairly high annual
precipitation
Fairly low annual
temperature range
Therefore, maritime
climate.
Toronto, huh?
While “the T Dot” is in the
interior of North America,
Lake Ontario moderates
the temperature and
causes slightly more
precipitation.
Toronto, ON
Small annual precipitation.
Large annual temperature
range.
Therefore, continental
climate
Regina, SK
Fairly low annual
precipitation
Fairly high annual
temperature range.
Therefore, continental
climate.
Prince George, BC
Very high annual
precipitation
Very low annual
temperature range
Therefore, maritime climate.
Now, do the handout.
Canada’s Climatic Regions
 Areas with similar climates:
– West Coast (maritime climate)
– Mountain
– Prairie (continental climate)
– Boreal (continental climate)
– Arctic (mainly continental climate)
– Southeastern (continental & maritime climate)
– East Coast (maritime climate)
Canada’s Climatic Regions
 West Coast (maritime climate)
– Usually mild and greatly affected by the
Pacific Ocean
Canada’s Climatic Regions
 Mountain (much variation)
– Differences in elevation
– Windward and leeward slopes
Canada’s Climatic Regions
 Prairie (continental climate)
– Cool in winter, warm summers
– In the rain shadow of the Western Cordillera
– Precipitation from convectional precipitation
Canada’s Climatic Regions
 Boreal (continental climate)
– Northern locations and interior positions
– Short summers & long winters
– Mainly convectional precipitation
Canada’s Climatic Regions
 Arctic (mainly continental climate)
– Very harsh climate
– Cold desert
– Less than 350 mm of precipitation each year
– Long cold winters (10 Months)
Canada’s Climatic Regions
 Southeastern (continental & maritime
climate)
– Climate affected by Great Lakes and Atlantic
Ocean
– Cyclonic precipitation caused by westerly winds
– Southerly storms formed in the Gulf of Mexico
Canada’s Climatic Regions
 East Coast (maritime climate)
– Cold Labrador current meets warm Gulf of
Mexico current causes a lot of fog
– Winters not very cold
– Summers not very hot
– Receives more than 1000mm of precipitation.