What Affects Weather and Climate?
There are FIVE Factors:
1. Ocean Currents
2. Air Masses
3. Latitude
4. Proximity to Water
5. Elevation
#1 Ocean Currents
• The world’s oceans are constantly in motion.
Tides move the water up and down while
currents move the water from place to place.
• Gulf Stream: Ocean current from the south. It
brings warm temperatures to the south-eastern
waters of the Atlantic provinces.
• Labrador Current: Flowing from the north. It
brings cold water to much of the Atlantic coast.
• When warm, humid air blows from the south
over colder waters, fog is formed.
How do ocean currents
affect climate?
Warm Currents: warmer climate
Cold Currents: cooler climate
#2 Air Masses
 Large volumes of air with similar temperatures and moisture
conditions.
 They affect the climate because they take on the temperature and
humidity characteristics of an area.
 It moves as a result of changing pressure conditions. It’s leading edge
is called a Front.
 Continental Arctic: This cold mass comes from Northern Canada
and feels cold and dry.
 Maritime Tropical: air that comes from the Caribbean and feels
warm and moist.
 Maritime Polar: air that comes from the Atlantic and feels cool and
moist.
Air Masses
When air masses meet at a front, the collision often results in changeable
weather, or rainfall.
Look at the illustrations of cold and warm fronts.
Describe how cold and warm fronts form. Can either kind of front bring
rainy or foggy weather?
Warm Fronts
• A warm front generally moves from southwest to northeast and the air
behind a warm front is warmer and more moist than the air ahead of it.
• When a warm front passes through, the air becomes warmer and more
humid than it did before.
•A warm front is represented by a solid line with semicircles pointing
towards the colder air and in the direction of movement.
Can you spot the warm & cold fronts?
Cold Fronts
Cold fronts generally move from northwest to southeast.
The air behind a cold front is noticeably colder and drier than the air
ahead of it.
As a symbol, a cold front is represented by a solid line with triangles
along the front pointing towards the warmer air and in the direction of
movement.
#3 Latitude
• One of the most important influences on climate is
latitude.
• How far north or south of the equator a region is
influences how warm or cold it will be.
• The amount of heat energy (radiation) that the earth
receives depends on the angle of the sun’s rays.
• Because the earth’s surface is round, sunshine is more
intense at the lower latitudes.
• Because the earth is tilted on its axis, sunshine also
varies with the seasons. During the summer, the sun’s
rays are closer, and therefore are also more intense!
How does latitude
affect climate?
Temperature
As latitude ________,
increases the average
decreases
annual temperature _________.
0°
Latitude
90°
#4 Proximity to Water
• Sunshine heats the land and water at different rates.
• Areas close to large bodies of water stay cooler in the
summer, and warmer in the winter than inland areas.
• This greatly influences the climate of communities that
are close to the ocean.
Continental and Maritime Climate
Continental Climate:
 Usually found in the interior of large land
masses.
 They are usually a long distance from large
bodies of water.
 These areas experience hot summers and cold
winters. The result is a large temp. range.
 Examples: Manitoba, Saskatchewan, Alberta,
parts of Ontario, parts of Quebec.
Continental and Maritime Climate
Maritime Climate:
• Usually found along the coastal areas near
the ocean.
• They experience a cool summer and a
relatively warm/mild winter.
• Examples: P.E.I., Nova Scotia,
Newfoundland, New Brunswick, parts of
Quebec.
How does closeness to a large
body of water affect climate?
moderates the temperature.
Water __________
Cooler summers. _______
Warmer winters.
_______
Cities A & B are located
at the same latitude.
City B is closer to a large
body of water.
Its temperature line is
flatter (moderated).
# 5 Elevation
(The Orographic Effect)
 As height increases, temperatures decrease.
 This is because the air is much thinner at higher
altitudes. For every 1000FT, the air temperature
drops by 1 degree!
 One of the THREE types of condensation is
orographic rainfall.
 This occurs when warm, humid air cools as it
rises over a high elevation (ex: A mountain)
 As air strikes, it is lifted and cooled. Windward
slopes of mountains tend to be rainy, while the
leeward side is dry. (Ex: West coast of BC)
The leeward
sides of the
Adirondacks &
Catskills
receive much
less
precipitation
The windward sides of the
Adirondacks & Catskills
receive a great deal more
precipitation
How does the
Orographic Effect
affect climate?
cool, moist
Windward Side: ___________
warm, dry
Leeward Side: _____________
During summer, temperature is strongly controlled by elevation -- cold at the
higher reaches of the Alaska and Brooks Ranges, and warmer in the lowlands.
How does elevation
affect climate?
Temperature
increases the average
As elevation _________,
annual temperature __________.
decreases
Elevation
The Three Forms of Condensation
• #1 Orographic Rainfall (already in your notes)
#2 Convectional Rainfall
 When warm, humid air rises after being warmed from a surface
below.
 As the air rises quickly it expands, cools, and water vapour
condenses (for ex: over the ocean, equatorial regions like the
rainforest.
#3 Frontal Condensation
 When warm, moist air rises over cold air
 When warm air collides with cool air along a front, the warm air is
forced to rise up and over the cool air
 As the warm air gently rises over the cool air, clouds form, and
condensation occurs.
Warm and Cold Fronts
When air masses meet at a front, the collision often results in changeable
weather, or rainfall.
Land and Sea Breezes
• Land Breeze: Occurs during the night. Air cools and
blows off the land towards the ocean.
• Sea Breeze: Occurs during the day. Air cools and blows
off the water towards the land.