Earth Energy Balance Slides

2. Contents
 What Is Energy Balance
 Objective Of Energy Balance
 Earth`s Energy Balance
 Earth`s Average Temperature
 Effect Of Greenhouse Gases
 Conclusion
 References

3. What is Energy Balance

4. Objective of Earth`s Energy Balance
“Recognize that temperature of earth depends
on the amount of solar energy that it absorbs”
 Radiative Equilibrium

5. Earth`s Energy Balance
“Energy Coming from Sun
and Going from the Earth
surface maintains earth`s
temperature”

6. Earth`s Energy Balance Contd.………..

7. Earth`s Energy Balance Contd.………..

8. Earth`s Energy Balance Contd.………..

9. Earth`s Energy Balance Contd.………..
heat absorbed by planet = (1 - a) πR2So
heat radiated from planet = (4πR2) σTe
4
In radiative balance we thus have:
(4πR2 ) σTe
4 = (1 - a) πR2So
Solving this equation for temperature we obtain:
Te = [(1-a)So / 4σ] 1/4
Where:
So = Solar Constant
a = albedo of earth
R = Radius of earth
σ = Stefan`s Boltzmann constant
(Energy Flux)
Te = Equivalent temperature
( 255 k or -18°C)

10. Earth`s Energy Balance Contd.………..

11. Earth`s Energy Balance Contd.………..

12. Earth`s Average temperature

13. Effect of Greenhouse Gases
Greenhouse gases in the atmosphere,
including water vapour, carbon dioxide,
methane, and nitrous oxide, act to make
the surface much warmer than this,
because they absorb and emit heat energy
in all directions (including downwards),
keeping Earth’s surface and lower
atmosphere warm.

14. What Happens when no greenhouses are present
When UV rays hits the earth surface, it is converted into infrared
And absorbed by GHG`s and sent back to earth`s surface, it means
Temperature of earth surface Increases.
IF no greenhouses are present, earth surface temperature
decreases.

15. What Happens when no greenhouses Gases are present

16. What Happens when more GHG`s are added
.

17. Conclusion

18. References
1.A critical review on “The Earth`s energy balance by Graeme L. Stephens and Tristan L `Ecuyer.
2. NASA Energy and water cycle study(NEWS)
3. www.google.com.
4. www.youtube.com.