13.2 Energy Systems
How Energy is Transferred
Energy (heat or light) is transferred in one of
the following ways:
 Radiation
 Convection
 Advection
 Conduction
Radiation
 the
transfer of energy by electromagnetic
(light) waves (electromagnetic spectrum)
 does not require a medium to travel through
(i.e. can travel through a vacuum)
 travels in straight lines
 is emitted (given off) by all matter
 the only form of energy given to us by the
sun
Convection

transfer of energy by vertical movement of
particles in a fluid (liquid/gas)
 as the particles gain energy they move faster,
take up more space, become less dense, and
then can rise through the fluid they are in
 this can create convection currents
 this method of heat transfer is very important
to weather
Advection
 Transfer
of energy through the collision of
particles in a liquid or gas
 Energy moves horizontally
Conduction

the transfer of energy which
occurs when a particle with
high energy hits a particle
with lower energy
 thus energy is passed
through an object from
atom to atom
 only occurs in solids, since
the particles must be close
together for frequent
collisions to occur readily
 What
energy is needed to survive on
Planet Earth?
 Hint:
Solar Energy

Where does it come from?


produced by nuclear fusion reactions in the sun
How does Solar Energy reach Earth?


Radiant energy travels in waves of different energy
levels, collectively known as the Electromagnetic
Spectrum
In order from lowest to highest energy level:
•
•
•
•
•
•
•
Radio
Microwave
Infrared
Visible
Ultraviolet
X-rays
Gamma
Electromagnetic Spectrum
Albedo

When solar energy strikes an object, some of the
energy is absorbed and some is reflected
 Albedo is a measurement of the percentage of light
which a material will reflect

Polar Ice Cap – High or Low?
• Answer: High

Black Roof – High or Low?
• Answer: Low

Bare Soil – High or Low?
• Answer: Low

The higher the albedo, the less energy absorbed
Heat Capacity:

a measure of how much heat a substance must
absorb to increase its temperature by 1degree C
 if a substance absorbs a lot of heat, yet its
temperature rises slowly, then it has a high heat
capacity
 think of the Yoho Lake & a sandy beach in the
summer


they both absorb the same amount of heat
the water stays cold because it can absorb a lot of
heat without its temperature rising, the sand on
the other hand gets very hot
Heat Sink
 an
object which absorbs energy and
becomes warmer
 a substance with a high heat capacity
makes a good heat sink
 water has a high heat capacity and so is a
good heat sink, while rocks have a low
heat capacity
 See Table in Text
Absorption and Reflection

solar energy entering the atmosphere can be
either absorbed or reflected
 both absorption and reflection can occur with the
air, clouds and the earth’s surface
 approximately 70% in total is absorbed





44% heat the Earth’s land surface and air
25% heat the water and evaporate some water
1% creates wind
Less than 1% is used for photosynthesis
approximately 30 % is reflected
(air 6%, clouds 20%, earth 4%)
Why is Solar Energy Important?

all forms of life on earth are dependent on solar
energy for life
 needed for plants to grow and to keep earth warm
enough for survival

Reminder: less than 1% is used by Photosynthesis.
• PHOTOSYNTHESIS – The process by which
green plants use sunlight to produce sugar.
CO2 + 2H2O + sunlight ---> O2 + (C6H12O6)n + H2O
or...
carbon dioxide + water + sunlight ---> oxygen + carbohydrate + water
ENERGY MOVEMENT IN ECOSYSTEMS
ENERGY MOVEMENT
IN ECOSYSTEMS
Chapter 1.11
Chapter 1.11
 Of
the less than 1% (0.023%), how does
the energy disperse throughout food
chains and food webs.
 FOOD
WEB – a series of interlocking food
chains
 When
talking about food webs and energy,
new terms are used to describe producers
and consumers/decomposers.
AUTOTROPHS
 Plants
or algae which make their own food
using the sun’s energy through
photosynthesis
 Previously
called producers
HETEROTROPHS
 Animals,
fungi and bacteria that must eat
or decompose plants or animals ( and their
waste) to get their energy.
 Previously

called consumers
/ decomposers
WHY NEW TERMS?

Each of the feeding levels ( consumer, primary
consumer, secondary consumer ) is called a
trophic level.
 Every time something is consumed in a food
chain, energy is passed along.
 However, less and less energy is passed on
each time because some of the energy is used
for life processes ( maintaining body
temperature, digestion, growing, movement, etc)
ECOLOGICAL PYRAMID

Third Trophic
level
Secondary
Consumers
Second Trophic
Level
Primary Consumers
First Trophic Level
Producers
Energy from the Sun
 With
these new terms and previous old
terms we can place labels on organisms
within food chains and food webs.
 Lets
look at Handout: Energy loss in a
food chain
Energy Loss in Food Chains
ENERGY LOSS IN A FOOD
CHAIN
The higher the trophic level in the food
chain, the more energy is lost.
Consuming plants, which are the lowest
trophic level, allows for the least
amount of energy to be lost.
A SIMPLE FOOD WEB
More Complex Food Web
HOMEWORK
 TEXT
PAGE 39
 QUESTIONS: #1-6, 9,10