Geog lesson on the 5th of Feb

All systems depend on regulatory forces and systems which might have

1. Positive feedback ---Consequence is enhanced. This feedback will drive the system further away from its original setpoint. It will encourage change and cause an unstable eqilibrium. Eg. enhanced greenhouse effect à world becomes hotter.

2. Negative feedback ---Will tend to re-establish equilibrium because it discourages change. It lets the system remain stable. Eg. Increase in carbon dioxide à reduce carbon emissions à carbon dioxide level will return to original level.

PLANETARY HEAT

Global shortwave radiation cascade absorbed by:
1. OZONE ( stratosphere) DIFFUSED INSOLATION
2. CLOUDS AND AEROSOLS ( troposphere)
3. Earth’s surface DIRECT INSOLATION

Global longwave radiation cascade emitted by:

1. EARTH’S SURFACE – directly to space
- Absorbed by greenhouse gases*
2. ATMOSPHERE – directly to space*
- Absorbed by earth’s surface
Heat comes from ~ surface emissions
~latent heat transfer
~sensible heat transfer
~absorption of shortwave radiation from atmosphere
Gases and clouds

*majority of the heat radiated

Key words:
Global shortwave radiation cascade : Rays from the sun entering earth
Global longwave radiation cascade: Rays that are reflected/ leaving the earth
Diffused insolation: Heat that is absorbed is scattered
Direct insolation: Suface that absorbs heat directly
Albedo: Amount of heat reflected back

Reflections:
The best way to remember the way in which planetary heat is balanced is to keep in mind that the incoming solar insolation and outgoing radiation must be equal in quantity. The planetary heat balance is a very important system to the Earth. In reference to Global warming today, there is enhanced greenhouse effect because of the increase in amount of carbon dioxide in the air which will trap more longwave radiation. Thus causing an increase in temperature on Earth. Yupps. So that is how the planetary heat balance can be used to explain why our climate is changing.

By: Valerie Yeo