1. The Sun: source of it all…
Sun 99.8% of mass of solar system
70% helium, solar flares
uv image

2. We are very small!
(NASA, TRACE)

3. Coronal loop

5. Blackbody radiation curves typical for the Sun and Earth
Sun ~6000K
Earth ~290K
Sun radiates a lot more energy that the Earth!

6. Normalized blackbody radiation curves for Earth and Sun
Divide each radiation curve by its maximum value
to normalize curves:
Very little overlap of the normalized radiation curves

7. The solar spectrum compared to a black body
Houghton, 2002

8. How steady is the Sun’s output?
Measurements of solar radiation from space,
rockets, and balloons
Note on short timescales, some large fluctuations are possible.
C. FRÖHLICH
IPCC, 2001

9. Solar variability: the sunspot cycle
Houghton, 2002

10. Reconstructions of solar variability over time
TSI = total solar irradiance
Note the scientific trend too…
IPCC, 2001

11. Solar insolation as as function of latitude
Incident
insolation
Reflected
insolation
Peixoto and Oort, 1992

12. Energy balance as a function of latitude
Albedo
Absorbed insolation
Emitted terrestrial
Net energy
Peixoto and Oort, 1992

13. Energy pathways in the climate system
ENERGY IN = ENERGY OUT
BUT LOTS OF COMPLICATED THINGS HAPPEN ON THE WAY…
Peixoto and Oort, 1992

14. Atmospheric absorption
Shortwave (i.e. solar) radiation measured from the top of
atmosphere and from the ground.
The (clear) atmosphere is not totally
transparent to solar radiation:
back scatter by dust, aerosols
absorption by constituent gases
amount varies as a function of
wavelength
Peixoto and Oort, 1992

15. Atmospheric absoption by atmospheric constituents
absorption
100%
Entire atmosphere 0%
> 11 km
CH4
N20
O2,03
CO2
H20
Peixoto and Oort, 1992

16. Longwave (terrestrial) radiation measured from space
Sahara
Mediterranean
Antarctica
Houghton, 2002