Slide 1

(a) linear & b (log-log) Planetary orbital periods versus distance from sun. Slide 2 perihelion aphelion Geometry of the earths orbit. (not to scale.) Slide 3 Center of sun to Center of earth Relationship of declination angle s to tilt of the earths axis. Slide 4 Position (solid lines) of the sun for Vancouver, Canada for various seasons. September 21 and March 23 nearly coincide. Isochrones are dashed. All times are pacific standard time Slide 5 Flux F through an area A into one side of a volume. Slide 6 Planck blackbody irradiance,,from the sun. Slide 7 Planck blackbody irradiance,,from the earth. Slide 8 Black-body irradiance E* reaching top of Earths atmosphere from the sun and irradiance of terrestrial radiation leaving the top of the atmosphere, plotted on log-log graph. Slide 9 Slide 10 Reduction of radiation across a path due to absorption by particles, illustrating Beers law. Slide 11 Typical diurnal variation of radiative fluxes at the surface. Fluxes are positive upward. Slide 12 Fate of sunlight en route to the earths surface.