Global Greenhouse Effect (steady-state)

vs. Global Warming

(disturbed steady-state)

Earth’s Energy Balance

Earth’s Energy Balance

• Visible and UV light from sun through atmosphere to earth

• Energy absorbed by earth

• Infrared light radiated from earth

• 84% of radiated IR light absorbed by “Greenhouse Gases”

• Energy in = Energy out

Disturbed Energy Balance

• Additional carbon dioxide in atmosphere

• >84% of radiated IR light absorbed by “Greenhouse Gases”

• Energy out<Energy inEnhanced greenhouse effect

Matter/Radiation Interaction

What’s a Greenhouse Gas??

•CH4 (methane), H2O (water), CO2 (carbon dioxide)

•NOT N2 (nitrogen), O2 (oxygen)

A greenhouse gas absorbs IR radiation

Specific Bending and Stretching, CO2

•Figure 3.6

Greenhouse Gases absorb radiation in the

IR region•For an absorption to occur, the

overall charge distribution in the molecule must change.

You must be able to make he molecule non-symmetric

Molecular “SHAPE”From 2D Lewis Structures to 3D

shapes

“ Electron groups around an atom will orient themselves as far

apart as possible”

Fig. p.115

Figure 3.10

CO2 Human

Contribution

How much carbon dioxide do you

generate when you have an outdoor

barbecue?

Two ways to quantify

•How many?–Particles–Moles of particles

•What mass?–Atomic weight (isotope average)

–Molar mass

Enhanced Global Warming?

Fig. 3.6

Relation between CO2 and Temperature

Fig. 3.2

True, False or Maybe?1. Carbon dioxide contributes to

an elevated global temperature.2. The concentration of CO2 in the

atmosphere has been increasing.

3. The increase in CO2 is due to human activity.

True, False or Maybe? Cont.

4. There has been an increase in average global temperature during the past century?

5. The greenhouse gases generated by human activity are responsible for the temperature increase.

True, False or Maybe? Cont.

6. The average global temperature will continue to increase as human emissions of greenhouse gases increase.

Climate Modeling

MANY variablesdifficult to identifydifficult to measureinteractions

3.9 Consider This: The CO2 Emissions-Implications for

Policy(page 109)

HomeworkRead distributed article and

identify two questions you would like to have answers to before you

could decide to endorse or not endorse the Bush administration’s

policy.(TYPED for FRIDAY)