Transcript 1. Climate SystemsNEW

The Earth’s Climate System
Is climate change new?
Climate change is a natural part of Earth’s history. For
example, thousands of years ago, thick ice sheets covered
most of Canada and a large portion of the United States.
Key Terms
• Weather refers to the
condition of the atmosphere
at a specific place and time.
It describes factors such as
wind, temperature and
humidity.
• Climate refers to the
condition of the atmosphere
over a large area, averaged
over many years.
Temperature and Climate
• The Earth is surrounded
by an envelope of gases
called the atmosphere.
• Without this envelop, the
days would be too hot and
the nights would be too
cold!
• So how is heat energy
transferred?
How is Heat Transferred?
• Heat is always transferred from the hotter object
to the colder object.
• There are three types of heat transfer:
Conduction
• The transfer of heat between substances that are in
direct contact with one another
• The better the conductor the more rapidly the heat
will transfer.
Convection
• The up and down movement of gases and liquids caused by
heat transfer.
• As a gas/liquid is heated it expands and rises because it is
less dense. As it rises and expands, it cools and falls. This
creates convection currents.
Radiation
• Electromagnetic waves moving through space.
These waves come in contact with an object
and transfer the heat to the object.
Earth’s Climate System
• A complex framework of interactions between various
factors that influence the Earth’s climate.
Earth’s Climate Systems
What does it involve?
• Atmosphere
• The Hydrosphere
•Lithosphere
These components interact with one another and with aspects of
Earth’s biosphere to determine not only day-to-day weather, but
also long term averages, climate.
Factors Affecting Climate Change
1. The Sun
2. The Earth
3. The Atmosphere
4. The Hydrosphere
5. Human Activity
Factors Affecting Climate Change
1. The Sun
2. The Earth
3. The Atmosphere
4. The Hydrosphere
5. Human Activity
Solar Energy
• The most important factor that affects climate is the sun
• Earth’s climate systems are driven by radiation energy
received from the sun.
• The intensity of the energy that reaches Earth’s surface
affects the temperature of air, water and land
• Heat produces winds, rain and other features of climate.
Changes in Solar Activity
• The Sun produces a variable
amount of energy.
• When the number of sunspots is
high, the Sun emits higher
amounts of solar radiation.
• Some scientists believe that
changes in solar output are the
main cause of climate change in
the past.
Factors Affecting Climate Change
1. The Sun
2. The Earth
3. The Atmosphere
4. The Hydrosphere
5. Human Activity
Factors on Earth that Affect
Climate
1.Rotation
2.Revolution
3.Tilt
4.Latitude
Solar Energy and the Earth
• The amount of solar energy that reaches Earth
depends on solar activity, the shape of the Earth and
the tilt of the Earth.
Rotation vs. Revolution a Review
• Earth rotates once every 24 hours (1
day) around its axis, an imaginary
line that goes from the North Pole to
the South Pole through the center of
the Earth.
• The Earth also revolves (orbits)
around the Sun every 365 and a half
days (1 year).
• Another important detail is that the
Earth’s axis of rotation is tilted at an
angle of about 23.5˚
Earth’s Seasons
The seasons are created by Earth’s revolution and its tilted axis.
Latitude
• Energy coming from
the sun is not
distributed uniformly
across the surface of
the Earth.
• Due to the shape of the
Earth, the energy is
most intense at the
equator and weakest
at the poles.
Temperatures Around the World
• This non-uniform energy distribution leads to
temperature differences.
Land Surfaces
• Earth’s outer layer is made of massive pieces of solid rock,
called tectonic plates.
• Earth has about 12 major plates that move at a rate of a few
centimeters per year.
• The plates carry the continents with them as they move.
• This means that the shape of the oceans and continents is
always changing.
The Movement of the
Continental Plates
• Patterns of air and water circulation are affected which in
turn affects the thermal energy around the world.
• The formation of mountain chains also affects the
patterns of wind and precipitation around the globe.
Volcanoes
• Most volcanoes are located at the boundaries of
tectonic plates.
• Plate movement affects climate by producing
volcanic activity.
• In these areas, molten rock and gases from below
the Earth’s crust rise up through cracks in the rock
and spew into the air as volcanic eruptions.
•
Volcanic
Eruptions
During a volcanic eruption, particles called
aerosols (such as ash) are released into the
atmosphere.
• Aerosols reflect solar radiation, having a cooling
effect on the global climate, and scatter light
• Some volcanic eruptions can raise global
temperatures by releasing greenhouse gases.
Factors Affecting Climate Change
1. The Sun
2. The Earth
3. The Atmosphere
4. The Hydrosphere
5. Human Activity
Atmospheric Factors that Affect Climate
1.Greenhouse Effect
2.Wind
The Atmosphere…
Earth’s Warm, Snuggly Blanket
• The Earth’s atmosphere is like a big blanket that
surrounds the globe keeping humans warm. If it was
suddenly stripped off, the Earth’s average
temperature would plummet and everything would
freeze.
• Like a blanket that could be made from a mix of
cotton and wool, the Earth’s atmosphere is made
from a mixture of gases.
The Earth’s Atmosphere
The atmosphere starts at Earth’s surface and goes up to about
560 km into space.
It is mostly made of nitrogen (N2) and oxygen (O2) gases as well
as water vapour, very low concentrations of other gases and
particles of solids.
The Greenhouse Effect
A natural process that keeps Earth’s temperatures within a certain
range.
Without it Earth’s average temperature would be colder
(approximately 34˚C lower) and most of the solar energy reaching
Earth would radiate out back into space.
The atmosphere contains greenhouse gases and solar radiation
passes through them. Solar radiation warms the surface of the
Earth and heat rises from the surface
Some heat is able to pass back through the gases and some cannot.
The heat that is trapped adds to overall global temperatures.
Wind
• Wind is caused by uneven heating of Earth’s surface.
• The air moves as wind transfers thermal energy around the
world from warm areas to cooler areas.
• It is the movement of air from an area of high pressure to an
area of lower pressure.
Prevailing Winds
• Winds blow in fairly constant directions around the
world. These are known as prevailing winds.
Wind
• Winds disperse energy throughout the
atmosphere.
• The movement of air affects:
– precipitation patterns
– ocean currents
Precipitation
• As air masses of different densities move across
the Earth’s surface, they interact.
• When air masses meet (called a front), one air
mass usually rises over the other.
• The rising air cools and any water vapour in the
air condenses to form precipitation.
Ocean Currents
• The difference in atmospheric temperature cause the
ocean to react and create convection currents. These
currents transport heat from the warm tropics to the cold
Polar Regions and back again.
Factors Affecting Climate Change
1. The Sun
2. The Earth
3. The Atmosphere
4. The Hydrosphere
5. Human Activity
The Hydrosphere
• Two thirds of the Earth is covered by oceans.
• The hydrosphere includes all of the water on
the planet in its different forms.
The Hydrosphere
• On Earth water is found in many forms:
– vapour and clouds of water droplets in the
atmosphere
– liquid in the oceans, seas, and smaller bodies of
water
– ice and snow in temperate and colder regions
Gas
Liquid
Solid
Specific Heat Capacity
• Oceans and lakes act as heat reservoirs. They buffer
temperatures in the atmosphere.
• Large bodies of water influence climate because
water has a large specific heat capacity compared
with other substances.
Specific Heat Capacity
• Specific heat capacity is the amount of heat
required to raise the temperature of one
gram of a substance by one degree Celsius.
• Water has a large specific heat capacity. This
means it takes more heat to raise the
temperature of 1 g of water by 1oC than it
does to do the same to many other
substances.
Specific Heat Capacity… So what?
• The higher the heat capacity, the longer it takes to warm the
substance up and the slower the substance loses its heat.
• Water’s high specific heat capacity means that a land mass
near a large body of water will have its temperature
“moderated” by the water – it will warm up more slowly in
summer and cool down slowly in winter than will a land mass
further from water.
The water will warm and cool more
slowly than the beach
25 degrees
20 degrees
Specific Heat Capacity
Some Common Specific Heat Capacity Values
Substance
Specific Heat Capacity in
“The number of joules of heat energy
needed to raise the temperature of 1 g
of the substance
by 1oC.”
Pure Water
4.18
Sea Water
3.89
Dry Air
1.00
Wet mud
2.51
Sandy soil
0.92
Snow and Ice
• Ice and snow reflect heat
• The light colour of ice and snow allow them to
reflect solar radiation.
• Because as we know, light-coloured surfaces
reflect energy, and dark surfaces absorb
energy.
Ice and Snow Reflect Heat
• The light colour of ice and snow allow them to reflect solar
radiation.
The amount of energy that is reflected by a surface is known as albedo.
• Light-coloured surfaces reflect energy, and dark surfaces
absorb energy.
Exampl
e:
• Because of their large differences in albedo, the distribution
of water, ice and land on Earth’s surface greatly affects the
average global temperature.
1.
Factors Affecting Climate
Change
The Sun
2. The Earth
3. The Atmosphere
5. Human Activity
4. The Hydrosphere
Burning of Fossil Fuels
Climate Systems
Recap
• What are 3 ways that heat is transferred?
Povide a diagram.
• Compare and contrast weather and
climate.
• What are the 5 main influencing factors on
Earth’s climate system?