Without a climate system, Earth would be much colder
(world ave -20 oC) , the climate system moderates Earth’s
temperature by trapping and storing energy from the Sun
and distributing it around the world, as a result the air
temperature remains relatively constant day and night
and the poles are less cold and the equator is less hot
(world average +14.7 oC)
BACKGROUND INFO:
 All things are made up of molecules
 When things get heated, they absorb heat
energy
 With more energy, molecules are able to
move faster
 When molecules move faster, the
temperature rises

Thermal Energy is energy resulting from the
motion of particles
 It is a form of kinetic energy and is transferred as
heat

Thermal Energy Transfer can occur by three
methods:
▪ Conduction
▪ Convection
▪ Radiation

View the following animation to get an overview
of these processes: heat transfer

Conduction is the transfer of thermal energy
through direct contact between particles of a
substance, without moving the particles to a
new location

Usually occurs in solids

View: Conduction in Solids
When heat is supplied to one end, molecules
at that end start to move more quickly
In the process, they bump into their
neighbours, transferring the kinetic energy
And so on, and so on……

Why is this less likely in liquids and gases?




Convection is the transfer of thermal energy
through movement of particles from one
location to another

Usually occur in fluids (liquids and gases)

Example with boiling water:
 Water at bottom of pan is heated first
 Heated water expands and density decreases
 Heated water begins to rise
 Cooler water with higher density from the sides of
the pan rush down to take its place
 The cooler water gets heated and the cycle
repeats
 We call these Convection Currents

Radiation is the emission of energy as waves
or particles or rays
 Radiation does not require a medium to transfer
energy
 Radiant energy is either reflected or absorbed by
matter
 Energy that is absorbed increases the kinetic
energy of the object
▪ This increases the temperature of the object

Example … the Sun
 Sun radiates energy in form of solar radiation
 When this energy reaches Earth, it is absorbed by
matter (air, water, land)
 Absorbed radiant energy increases kinetic energy
of the matter, raising its temperature

The Sun is an emitter
 It gives out heat

The Earth is an absorber
 It takes in the heat

Almost all energy on Earth
comes from the sun
 Electromagnetic spectrum,
including infrared radiation
and UV radiation

When solar radiation contacts a particle of
matter, one of three things happens:
1. Radiation is absorbed by a particle, causing the
particle to gain energy
2. Radiation is transmitted through the particle
3. Radiation is reflected off the particle
Break down of the Radiation that reaches Earth (by
percentage):
30% reflected back into space by clouds,
atmosphere and Earth’s surface
 30% of remaining 70% is absorbed by the
atmosphere
 The rest (40% of 70%) warms the Earth’s surface:

 Returns heat to atmosphere as infrared radiation,
thermal energy and water vapour

Net Radiation Budget  the difference between the amount of
incoming radiation and the amount of outgoing radiation
Net radiation budget = incoming radiation – outgoing radiation
= zero (theoretically)

Do all regions on Earth have a zero net radiation? Explain!
 Not all regions have a balanced radiation budget (but Earth as a
whole does)
 E.g. polar regions have less incoming than outgoing radiation
 E.g. tropics have more incoming than outgoing radiation
ALBEDO
1.


Colour of the surface
Albedo is the percentage of the incoming solar
radiation that it reflects
Albedo of Earth is about 30%
Light-coloured, shiny objects reflect more solar
radiation and have a high albedo (ice, snow, sand)



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Ice and snow reflect heat because they are white. They
reflect so much of the Sun’s energy that it is hard for these
locations, like the Arctic, to get very warm.
Darker, dull objects absorb more solar radiation and
have a low albedo (forests, soils)
Surface Temperature
2.
•
The higher the surface temperature, the higher
the rate of transfer
Surface Area
3.
•
The larger the surface area, the higher the rate
of transfer

Three methods of Heat Transfer
 Convection, conduction, and radiation

Earth’s Net Radiation Budget = “zero”
 Factors affecting radiation:
▪ Albedo
▪ Surface temperature
▪ Surface Area
1.
The amount of the energy the Earth absorbs is equal to the amount of energy it
radiates. Why is this important? Explain. [Knowledge]
2. The Sun shines continuously on Earth. Explain why Earth does not keep warming up.
[Thinking]
3.
a) Describe what happens to the Sun’s energy once it reaches Earth. [Knowledge]
b) Describe what happens to the energy Earth emits. [Knowledge]
4. What would you expect to happen to the temperature of Earth if [Thinking]
a) the amount of energy radiated by Earth increased but the amount of energy coming
from the Sun stayed the same?
b) the amount of energy radiated by Earth decreased but the amount of energy coming
from the Sun stayed the same?
5. State two reasons why you would expect the climate in Nigeria to be warmer than the
climate in Greenland. [Thinking/Application]
6. Explain why the greenhouse effect is important to life on Earth. [Knowledge]
7. Describe how the greenhouse effect in the atmosphere works and draw a diagram
illustrating it. [Thinking]
8. a) Write a definition, in your own words, of “greenhouse gas”. [Knowledge]
b) Name the two most important greenhouse gases that occur naturally in the
atmosphere. [Knowledge]
9. If forests serve as important sinks for greenhouse gases, describe how past ice ages
might have affected the concentration levels of carbon dioxide in the atmosphere.
[Application]
10. Give one natural source for each of the following greenhouse gases: [Application]
a) carbon dioxide
b) methane
c) nitrous oxide
d) water
Go to the Ecokids.ca Climate Change Games
and Activities. Spend ~ 5minutes playing each
of the games listed as “Intermediate”. Identify
one new thing you learned by playing the
games that surprised you about climate
change. Why were you surprised?