1. The Earth’s Temperature: Factors

2. The Sun!!!

3. Incoming Solar Radiation = Insolation
Referred to as short-wave radiation
Not constant at all latitudes – tilt of the Earth
More radiation at the equator, less at the poles

6. Processes affecting Insolation
Scattering – causes insolation to be displaced into many different directions
Some lost back to space
So the radiation may be scattered

8. Reflection - possible 100% loss of insolation back to space
Interaction with different surfaces or clouds/water vapor

10. Absorption - Insolation is absorbed, heats up the surface and then causes radiation of its own to be released
Long-wave radiation is emitted from the earth’s surface
This is also known as infrared radiation

13. Albedo
The percentage of solar radiation reflected back into space
Light colours reflect = high albedo
Dark colours absorb = low albedo
So things that are light coloured (snow) reflect more radiation, while darker things like concrete absorb more radiation

15. Reflectivity of the Earth’s Surface

16. Lapse rate and aspect
As altitude increases, the temperature drops
For every 150m increase in altitude, the temperature drops by 1°C
This is known as the lapse rate
This is why mountaintops are often covered in snow all year - they don't heat up enough to melt

17. Aspect refers to the direction something faces
In the Northern Hemisphere, hillsides facing South receive more direct energy.
Remember, the sun is over the Equator, so if you are in the N Hemisphere the sun is South of you.
What about the Southern Hemisphere?

18. Take a look at figure 17.3 on p.76 of your text
Notice how both lapse rate and aspect affect the temperature?

19. Seasons The earth is tilted on its axis at 23.5°
It completes one orbit of the sun every year
Because of this axial tilt, different latitudes receive different amounts of radiation over the course of the year

21. The effect of water
Water heats and cools more slowly than land
Areas close to water have smaller changes in temperature over the course of the seasons, while areas far from the sea have hotter summers and colder winters
Warm ocean currents can also help warm otherwise cold places - eg. Gulf Stream

22. The Energy Budget
Incoming solar radiation (or insolation) is also known as UV or ultraviolet radiation.
Insolation heats the planet.
The earth emits IR or infrared radiation, which cools the earth.
When one of these factors changes it can have great conquest for global temperatures

23. Greenhouse Gas Effect
Gases in the atmosphere, particularly carbon dioxide and methane, are able to trap some long-wave radiation.
Reflects this energy back to the Earth, which heats up the Earth even more.
This process is necessary to make the earth warm enough to be livable.
However, by greatly increasing the amount of greenhouses gasses, we have affected global temperatures.

24. Without it? Earth would be -18 degrees

27. Questions 1. Explain how the earth is heated.
2. After watching the video, explain why the Earth has seasons.
3. Explain why the length of days and nights are more even near the equator.
4. In your own words, explain the greenhouse effect.