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Climate
Weather vs. Climate
• Weather – the condition of Earth’s
atmosphere at a particular time and place.
– Short-term: Hours and days
– Localized: Town, Region or State
• Climate – the average, long-term, conditions
of an area.
– Two Factors:
• Temperature
• Precipitation
Temperature
• Factors that influence temperature:
1.
2.
3.
4.
Latitude
Altitude
Distance from large bodies of water
Ocean currents
Latitude
• The distance north or south of the equator,
measured in degrees.
– Farther North or South you go the colder the
temperature gets.
•
Sun’s rays hit the earth with more of an angle and
reflect more of the sun’s energy – angle of insolation.
– 3 Climate Zones based on Latitude:
•
•
•
Tropical Zone
Polar Zone
Temperate Zone
Angle of Insolation
Tropical Zone
• The area near the equator, between 23.5° N and
S latitude.
– Receives direct or nearly direct sunlight all year
round.
• Warm climate
Tropical Zone
Temperate Zones
• The areas between 23.5° - 66.5° N or S
latitude.
– Temperatures range from warm summers to cold
winters.
Temperate Zone
Temperate Zone
Polar Zones
• Extend from 66.5° – 90° N or S latitude.
– Receives the least amount of solar radiation and
therefore have the coldest climates.
Polar Zone
Polar Zone
Altitude
• The elevation above sea level.
• In the case of high mountains, altitude is a
more important climate factor than latitude.
– The higher up you go in the troposphere the
colder the atmosphere gets.
Distance from Lg. Bodies of Water
• Marine Climates
– Water warms up more slowly than land; it also
cools down more slowly.
• Winds from the ocean keep coastal regions from
reaching extremes of hot and cold.
– Warmer winters and cooler summers
• Continental Climates
– Have more extreme temperatures due to the
distance away from oceans.
• Winters cold, summers hot.
Ocean Currents
• Streams of water within
the oceans that move in
a regular pattern.
– Warm water from the
tropical zone moves
toward the polar zones.
– Cold currents from the
polar zones moves toward
the equator.
Factors Affecting Precipitation
• The amount of rain and snow that falls in an
area each year is determined by how wet or
dry the climate is.
• Two Factors:
1. Prevailing winds
2. Mountains
Prevailing Winds
• Weather depends on the movement of air
masses from place to place by prevailing winds.
– Different air masses carry different amount of water
vapor.
• Warm air can carry more water vapor than cold.
• Cold air masses are usually dry.
– Where an air mass develops also determines the
amount of water vapor an air mass carries.
• Marine = wet
• Continental = dry
Mountains
• A mountain range in the path of prevailing
winds can also influence where precipitation
falls.
– Mountains act as a barrier as warm air rises,
water vapor condenses and rain falls.
• Windward = the side of the mountain facing the wind
– Receives lots of rainfall
• Leeward = the side of the mountain facing away from
the wind
– Receives little rainfall (Rain shadow)
Windward vs. Leeward
Climate Change
• Throughout Earth’s history, climates have
gradually changed.
– Ice Ages – glacial episodes
• Periods where huge sheets of ice, glaciers, covered
large parts of Earth’s surface.
• Last ice age ended about 10,500 years ago.
– Interglacials
• Periods of warmer weather between ice ages.
– It is believed that we are currently in an interglacial right now.
Causes of Climate Change
• Natural factors:
1. Continental drift - the movement of landmasses.
2. Changes in the sun’s energy output – energy output
changes with an 11 yr cycle
•
Sunspots – cooler regions of the sun
3. Earth’s Position Relative to the Sun
•
Angle at which Earth’s axis tilts and the shape of Earth’s
orbit around the sun change slightly over long periods of
time.
Causes of Climate Change
• Human Factors:
1. Greenhouse Effect = gases in the atmosphere trap
solar energy and keep the Earth warm; water vapor,
carbon dioxide and methane.
•
Too much of these gases make the atmosphere warmer
than needed = global warming.
–
Burning of fossil fuels add carbon dioxide to the air.
2. Ozone depletion = the loss of the protective ozone
layer in the stratosphere that filters harmful UV
radiation from the sun.
•
Chlorofluorocarbons, a group of chlorine compounds,
were to blame for the breakdown of the ozone.
Antarctica