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13-Weather and Climate Notes CGC 1P1 and CGC 1D1

Read Chapter 12 in “Making Connections”

Weather: Day to day condition of the atmosphere

- short term – - small area - cities- to predict – 5 day forecast

Temperature, humidity, precipitation, wind speed, cloud cover, air pressure

Climate: Patterns of weather that have occurred over a of time

- long term - - large areas – countries, continents, the globe - to predict – summer, winter

Examples: continental climate, maritime climate, arid climate

Why does Canada have so much climatic variety?

1. Canada extends for a great distance from north to south (4,500 km), from 41°N in Lake Erie to 83°N on Ellesmere Island.

2. Canada has a from sea level to 5,959 metres (Mount Logan).

3. The long and vast areas are a great distance from the modifying influence of the .

4. Southern Canada is often the battle zone between from Arctic regions and , moist air from the south.

Can you answer the question: Vancouver is further north than Toronto, yet it is warmer and has more precipitation. Can you explain why this is the case? If you can’t answer it yet, hopefully you will be able to do so soon!!

Canadian Climate Map

LEGEND: CLIMATE REGIONS

Artic

Taiga

Cordilleran

Pacific Maritime

Boreal

Prairie

Southeastern

Atlantic Maritime

Factors that affect Climate:

Latitude

Solar energy delivered by varies with latitude – different intensity.

At latitudes (i.e. North Pole), the solar energy is concentrated and spread over a larger surface area…It is therefore .

At latitudes (i.e. equator), the solar energy is concentrated, spread over a smaller surface… It is therefore .

This diagram is shows how the angle of incidence changes with latitude.

The earth is always at a degree tilt.

The northern hemisphere changes from being tilted toward the sun ( ) to being tilted away from the sun ( ).

Remember these from earlier in the year??

Summer Solstice - most direct sunlight is at the most northern point from equator. Days are . June 21-22

Winter Solstice - most direct sunlight is at the most southern point from equator. Days are . December 21-22

Ocean Currents

Ocean currents are and pockets or streams of water that move throughout the ocean. They affect .

If a cold ocean current passes by, it will cool the surrounding air.

If a warm ocean current passes by, it will warm the surrounding air.

Winds and Air Masses

An air mass is a large with almost the same temperature and moisture throughout. An air mass takes on the climate characteristics of the areas where it was formed.

Air masses move from areas toward areas. This moving air causes wind.

E.g. An air mass originating from the Arctic is cold and dry. It moves southward and is carried by the westerly winds, bringing cold dry air across Canada.

FRONTS: The two air masses with different temperature and moisture content.

WARM FRONT – leading edge of a warm air mass COLD FRONT – leading edge of a cold air mass

Air Pressure is caused by the weight of the .

- Low Pressure is associated with air that has expanded and is rising. - High Pressure is associated with air that has contracted and is falling.

Like Air Masses, Winds move from pressure to pressure.

Winds are created by differences in air pressure. Around the world there are belts of low and high pressure. As they move around each other, they create a well-established pattern of prevailing winds that blow from to in Canada.

Due to the fact that the Earth is Rotating, we get what is known as the Coriolis Effect on the movement of the air masses or wind. Instead of winds moving in one straight north/south line, they are deflected to the in the NORTHERN Hemisphere and to the in the SOUTHERN HEMISPHERE.

This is due to the rotation of the earth (eastward). Hence, we have “westerlies” instead of “northerlies”.

Prevailing winds: Winds that blow in almost at these latitudes.

In Canada, the prevailing winds blow from . These are called “westerlies”.

They move air masses that affect our climate.

The JET STREAM:

The JET STREAM is a band of moving high above the Earth's surface from west to east.

There are jet streams in the Northern Hemisphere. The polar jet stream is located at the boundary between cold air to the north and warm air to the south.

Elevation

Elevation refers to how high or low we are on or above the earth’s surface. As you hike up a mountain, the temperature drops.

Why does it get colder even though you get closer to the sun?

This is technically referred to as the . The lower the elevation, or altitude, the the air pressure. As air rises, it expands because of lower air pressure.

Air heats up, becomes less dense, . As air pressure drops, air expands, and heat is lost…Now it will …until it condenses. As air expands, it cools.

The Rate of Temperature Drop BEFORE condensation: (DRY LAPSE RATE)

1 degree Celsius / 100 meters

Rate of Temperature Drop AFTER condensation: (WET LAPSE RATE)

0.6 degrees Celsius / 100 meters

Relief

Relief refers to caused by features on the landscape. For example, a mountain range is a type of relief. Even a small barrier like a building can cause a temperature difference.

Mountain ranges act as barriers to the movement of . They also cause precipitation to occur, called Relief or Orographic

Precipitation.

Air is forced to over a hill or mountain. As air away from the heat source (the ground up by the sun) the air cools by 1°C per 100m.

As the water vapour in the air condenses, it forms clouds and then rain. Air that has cooled cannot hold as much water as warmer air.

The air starts to down the hill or mountain and begins to up again.

As air up, it can hold more water and as it has lost water through precipitation, the air has less water overall. Therefore clouds disappear and rain stops. This side of the relief feature is known as a RAINSHADOW.

Near Water

Moderating Effect of large bodies of Water:

Water more slowly than land.

In the summer, wind blowing from the water will be

In the winter, wind blowing from the water will be .

Places near large water bodies are MODERATE - they do not get as cool or as warm as others

Maritime Climate: – Wetter overall

Continental Climate: – Dryer overall

Precipitation and Temperature – CLIMATE GRAPHS

Climate Graphs - See p.141-144 in MAKING CONNECTIONS

STATION A

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year

Ave. Monthy Temp ᵒC

-14 -11 -5 4 10 14 16 15 10 4 -6 -12 2.1

Ave. Monthly Prec. mm

23 15 16 22 43 76 101 70 47 18 16 19 466

STATION B

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Year

Ave. Monthy Temp ᵒC

-9 -8 -3 3 9 15 19 18 13 7 2 -6 5.0

Ave. Monthly Prec. mm

120 96 117 101 91 93 103 81 81 106 114 126 1229

1) Fill in your chart using the climate stations A and B from the data given above – see also Fig.12-22 (pg.144)

Location Average Temperature

Temperature Range

Total Precipitation

Seasons of Maximum Precipitation

Continental or Maritime?

AB

2) Draw the climate graphs for stations “A” and “B” - Be sure to use BLUE for the Precipitation Bar Graph, and Use RED for the Temperature Line Graph

Station “A”

Temperature in ________________

Precipitation in ________________

J F M A M J J A S O N D

Station “B”

Temperature in ________________

Precipitation in ________________

J F M A M J J A S O N D

3) In which climate is each station located (maritime or continental)? Explain how you reached your decision.

4) What climate factors do you think affect the climate the most at these stations?

5) What factors help us to decide if a location is in a maritime or continental climate?