1. Heat Energy Transfer
SNC2D

2. The Transfer of Heat Energy
There are 3 different mechanisms by which heat energy may be transferred:

3. The Transfer of Heat Energy
There are 3 different mechanisms by which heat energy may be transferred:
radiation

4. The Transfer of Heat Energy
There are 3 different mechanisms by which heat energy may be transferred:
radiation
conduction

5. The Transfer of Heat Energy
There are 3 different mechanisms by which heat energy may be transferred:
radiation
conduction
convection

6. Radiation
Radiation is the release of infrared radiation by a substance at a higher temperature than its surroundings.

7. Radiation
Radiation is the release of infrared radiation by a substance at a higher temperature than its surroundings.
This is the only mechanism that works in a vacuum (outer space, including the space between the Earth and the Sun).

8. Conduction
Conduction is the transfer of kinetic energy (the energy of motion) between particles in direct contact.

9. Conduction
Conduction is the transfer of kinetic energy (the energy of motion) between particles in direct contact.
Conduction is therefore most effective in solids.

10. Convection
Convection is the movement of particles from one location to another: cooler, denser material will sink relative to warmer, less dense material.
Convection is therefore most effective in liquids and gases.

11. Solar Radiation
So energy arrives from the Sun in the form of radiation (both visible and infrared).
However, not all of this energy is absorbed. Some is reflected. The percentage of radiation reflected is the albedo of the surface. Ice and snow reflect sunlight more than land or ocean.

12. Solar Radiation

13. Solar Radiation
Different surfaces also have different temperature responses to the same heat energy input.

14. Solar Radiation
Different surfaces also have different temperature responses to the same heat energy input.
E.g. water has a high heat capacity, which means that it takes more energy to heat the oceans than the land (which is why the water at the beach on a summer’s day is colder than the sand).

15. Solar Radiation
Also, arriving solar radiation is not distributed evenly: the equatorial regions receive, on average, more direct sunlight than the polar regions.

16. Heat Transfer on Earth
All this uneven heating of the Earth’s surface results in the transfer of heat energy (primarily from the equatorial region to the poles) by convection in the Earth’s atmosphere and hydrosphere.

17. Convection in the Atmosphere
The warm, moist air at the Equator rises and releases its moisture (resulting in rainforest biomes) and cools, sinking down at about 30o North and 30o South latitude (resulting in desert biomes).

18. Convection in the Atmosphere
Because the Earth is rotating, the Coriolis Effect forces the surface air moving toward the Equator from east to west, resulting in the NE and SE trade winds.

19. Convection in the Atmosphere
Similar convection cells between 30oN and 60oN and 30oS and 60oS latitudes result in prevailing westerly winds (which is why the weather across Canada moves from west to east).

20. Convection in the Hydrosphere
The patterns of ocean currents are complicated by the position of the continents.

21. The Effects of Climate Change
It is important to understand how heat energy transfer affects the climate to understand how global warming can change climate.

22. The Effects of Climate Change
E.g. global warming has resulted in increased evaporation from the oceans, resulting in increased precipitation of snow over the Northern Hemisphere (Siberia in particular), resulting in increased albedo, resulting in colder winters.

23. The Effects of Climate Change
E.g. the increased melting of glaciers and Arctic ice could result in increased cold ocean currents from the Arctic, possibly reversing the North Atlantic Drift that keeps Europe temperate.

24. More Practice
p. 289 # 6, 7, 8, 12, 13 p. 292 #7, 16