Topic 2: Thermal Energy Transfer

Why doesn’t the water get as hot as the seatbelt?

Consider these 3 Canadian cities…

… what makes their climates so different?

City Latitude

Average

Annual

Temperature

C

Vancouver,

BC49.11 N 10.1

Lethbridge,

AB49.38 N 5.7

Gander,

NF48.56 N 3.8

Net Radiation Budget

Balancing the Net Radiation Budget

• Thermal energy concentrated at the equator is spread out

towards the poles via the atmosphere and the hydrosphere

Thermal energy can be transferred in two ways:

Thermal Energy Transfer in the Atmosphere

• Warm air at the equator

is exchanged with cool

due to their different

densities (hot air rises;

cold air sinks)

• The movement of air

forms convection

currents that circulate

and distribute heat

around the world.

Coriolis Effect

• https://www.youtu

be.com/watch?v=i

2mec3vgeaI

The Coriolis Effect

• Land at the equator is rotating at a greater

speed than land at the poles

• Convection currents or any other moving

objects on Earth’s surface tend to veer

sideways from their original course due to

Earth’s rotation on its axis.

• This is called the Coriolis effect and it is the

reason storms spin opposite direction in the

Northern and Southern hemispheres

Jet Streams

• Jet streams are currents of extremely fast moving air in the upper troposphere

• Jet streams form at boundaries between warm and cold air due to a combination of convection and the Coriolis effect.

• How could airplanes take advantage of jet streams?

Thermal Energy Transfer in the Hydrosphere

• Just like there are

convection currents in the

atmosphere, they are also

in the ocean

• The global ocean currents

exchange warm and cool

water, thereby spreading

warm water around.

• Cold water sinks while

warm water rises

The Gulf Stream

• The Gulf Stream is a 100km wide surface current that starts in warm,

shallow seas of the Caribbean and continues up the North American coast

before curving towards the British Isles where it becomes the North

Atlantic Drift

• What would happen if the Gulf Stream stopped

circulating?

The Gulf Stream

• https://www.youtube.com/watch?v=hzCvY0ENrhk

• https://youtu.be/L

-bXLPLCyek

El Niño• https://gizmodo.com/video/3600033

?jwsource=cl&utm_medium=sharefr

omsite&utm_source=Earther

• You have learned about 3 factors that

affect climate:

– Insolation

– Air currents in the atmosphere

– Ocean currents in the hydrosphere

• Of these 3 factors, insolation has the

strongest effect on the climate of a

region

Consider these 3 Canadian cities…

… what makes their climates so different?

City Latitude

Average

Annual

Temperature

C

Vancouver,

BC49.11 N 10.1

Lethbridge,

AB49.38 N 5.7

Gander,

NF48.56 N 3.8

Specific Heat Capacity

• The reason proximity to

water has such a huge

effect on climate is due to

its specific heat capacity.

• Specific heat capacity is

the amount of thermal

energy it takes to raise the

temperature of a

substance.

Specific Heat Capacity of Water

Specific Heat Capacity• A higher specific heat

capacity means it takes

more energy to increase

the temperature of a

substance

Substance

Specific Heat

Capacity

(J/g•C)

Pure water 4.19

Sea water 3.89

Alcohol 3.46

Ice 2.00

Moist air 1.15 (varies)

Dry air 1.00

Aluminum 0.90

Steel 0.50

Iron 0.5

• This explains why the

steel seatbelt gets

screaming hot while the

water in the bottle does

not.

• About 70% of Earth’s

surface is covered by water,

so the capacity of water to

absorb thermal energy has a

huge effect on climate.

• Due to specific heat capacity

of water the hydrosphere

heats up and cools down

slowly compared to the

lithosphere and atmosphere.

Climatographs

How would you explain why the air temperature

tends to vary more with the seasons in

Lethbridge than Vancouver?

Coastal Cities

• Coastal cities like

Vancouver experience

less variation in

seasonal temperatures

because the ocean

water, which doesn’t

easily change

temperature, keeps the

air temperature more

consistent.

Calculating Heat Transfers

TmcQ =

The Quantity of Thermal Energy (Q) is the amount of

thermal energy absorbed or released when the

temperature of a substance changes.

Energy

gained in

Joules (J)

Mass in

grams (g)

Specific

heat

capacity

Change in

temperature

in degrees C

Calculating Heat Transfers TmcQ =EXAMPLE

A 50.0 g mass of water at 25.0C is heated to 50.0 C on a hot plate.

Determine the amount of energy transferred.

Calculating Heat Transfers TmcQ =EXAMPLE

How much thermal energy must be released to decrease the

temperature of 1.00 kg of water by 10.0C, given that the theoretical

specific heat capacity of water is 4.19 J/g•C?

ANSWER KEY

1. 2 x 104 J of energy was absorbed by the water to increase its

temperature.

2. 3.23 x 104 J of thermal energy was required to raise the

temperature of the water.

3. 1.26 x 103 J of thermal energy was released to decrease the

temperature of the water

4. 3.00 x 104 J of energy was required to warm the ice.

Note: cice = 2.00 J/g•C (this should have been provided for you!)

Note: Some of the questions are

missing specific heat capacity

information. Unless you’re

supposed to solve for c, it will

always be given to you.

cwater = 4.19 J/g•C

Calculating Heat Transfers TmcQ =EXAMPLE

Calculate the change in temperature, t, that occurs when 8.38 kJ of

thermal energy is added to 100.0 g of water. The theoretical specific

heat capacity of water is 4.19 J/g•C.

Calculating Heat Transfers TmcQ =EXAMPLE

When 21.6 J of thermal energy is added to a 2.0 g mass of iron, the

temperature of the iron increases by 24.0C. What is the

experimental specific heat capacity of iron?

ANSWER KEY

5. The water temperature increased by 20.3C

6. The water decreases in temperature by 0.119C, while

the iron decreases in temperature by 1.11C

7. The experimental specific heat capacity of the object is

0.130 J/g•C.

Note: Some of the questions are

missing specific heat capacity

information. Unless you’re

supposed to solve for c, it will

always be given to you.

cwater = 4.19 J/g•C