Cousin Ricky <ric### [at] yahoocom> wrote:
> I just plotted the spectral curve for ES_Sunlight (filtered sunlight)
> from espd_lightsys.inc and compared it to figure 3 at:
>    https://www.newport.com/t/introduction-to-solar-radiation
>
> The curves are similar in shape, but the Lightsys curve is higher in the
> red region, while the Newport curve is highest in the blue and green
> regions.  What would account for the difference?
>
> Newport.com's curve is for the Sun at zenith.  What was Pedro Aphalo's
> source?  Could Pedro's curve have been measured with the Sun at a lower
> angle?

I just compared the derived color of ES_Sunlight with actual sunlight reflected
off a sheet of white paper less than an hour after sunrise (more than 5 air
masses by my estimate), and the derived color was considerably more orange.
Assuming my monitor is halfway decently calibrated, the ES_Sunlight measurements
must have been taken through some serious air mass.

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