Download Grade 10 Applied Science – Climate Change

Grade 10 Applied Science – Climate Change
Energy Transfer in Air and Water
Water has a remarkable ability to absorb and store thermal energy. Thus, water is a HEAT SINK.
How is climate impacted?
 When air is warmer than the ocean surface, the ocean ABSORBS thermal energy FROM the
air. Likewise when air is cooler than the ocean surface, the ocean RELEASES thermal
energy TO the air.
 As a result, the climates of regions close to oceans and large bodies of water (e.g., Great
Lakes) tend to have more moderate climates (i.e., mild winter and cool summers).
When thermal energy is transferred, it always moves from a WARM object or region to a
COOLER object or region. There are four ways to move or transfer thermal energy:
 Radiation (e.g., electromagnetic waves)
 Conduction (e.g., through contact)
 Advection (e.g., horizontally through a liquid or gas)
 Convection (e.g., vertically through a liquid or gas)
Most of the energy transfer in air and water occurs via
CONVECTION CURRENTS…the circular movement of
matter within a fluid or gas caused by the rising of warm
fluid as cool fluid sinks. The picture shows air rising and
falling in a convection current pattern during day and night
times.
Energy Transfer in the Atmosphere
 Warm air is less dense while cold air is more dense
 Air at the Earth’s equator heats up quickly and becomes less dense.
 Cold, dense air higher in the atmosphere drops below the warm air and pushes the warm air
up into the atmosphere. This is an area of LOW PRESSURE.
 The warm air spreads out towards the
North and South Poles, and at the
higher altitude, begins to cool and
become dense.
 As cooler air, it sinks backs towards
the surface of the Earth. This is an
area of HIGH PRESSURE
 This movement of cool and warm air
creates a convection current in the
atmosphere.
 As shown in the picture, many
convection cells form around the
Earth. The cells cause prevailing
winds and the movement of thermal
energy towards the North and South
Poles.
 The movement of winds impact climate in a region. As wind moves over water, it picks up
water vapour via evaporation. When the wind reaches land, the water condenses and
precipitation occurs.
Energy Transfer in the Oceans
 Ocean currents also transfer thermal energy and affect climate.






Oceans currents are driven by three factors: (1) prevailing winds that move warm water on
the surface, and (2) convection and (3) uneven concentrations of salts in ocean waters that
move cold subsurface waters.
The movement of water based on
differences in temperature and
salt concentration is called
THERMOHALINE
CIRCULATION. It moves water
and thermal energy from the
equator to the poles.
Warm surface water moves to
the poles and get colder. It also
becomes more salty as some
water evaporates. Now cold and
salty, the water sinks to the
ocean floor. Warm water flows in
to replace it and a current is
formed.
Cold ocean currents cool the air above them. The cool air then cools nearby land. Since
cool air cannot hold moisture, the climate is cool and dry.
Warm water heats the air above it. Warm air carries moisture. The climate is warm and wet.
When warm and cold ocean currents meet, fog forms.
Make an ocean current
Purpose: To observe convection currents
Materials
 Two colours of food colouring
 Fish tank or large clear glass container
 Water
 Heat Lamp
 Sealed bag of ice cubes
Methods
 Fill the container nearly full of water
 Plug in the heat lamp, turn on and shine at one end of the container
 Lower the bag of ice cubes into the other end of the container
 Add one colour of food colouring to the water at the end of the container beside the heat lamp
 Add the other colour of food colouring to the water next to the ice cubes
 Record your observations