The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Figure 1.1 (a) The Sun's spectral irradiance
(solid line, typical of solar minimum conditions) is compared with
the spectrum of a black body radiator at 5770 K (dashed line). The
broad spectral bands identified along the top of this figure are
the ultraviolet (UV), visible (VIS), and infrared (IR). Not shown,
at wavelengths longer than the IR, is the microwave or radio
portion of the solar spectrum. (b) Approximate amplitude of the
Sun's spectral irradiance variation from the maximum to minimum of
the 11-year activity cycle. The solar cycle variation in the
spectrally integrated, or total, solar irradiance is indicated by
the dot-dash line. From J. Lean, Reviews of Geophysics, 29, 506,
1991, copyright by the American Geophysical Union.