Natural light comes from the sun, even if it comes from the moon. Mid-day light has a colour temperature of somewhere around 5600 Kelvin, what our eyes and brain interprets as white. Our digital cameras work best in the “white” range even though Auto White Balance is turned on.
We need to pay attention to white balance because our brains have the ability to correct for white under many different lighting conditions but our cameras don’t share that ability. Auto White Balance comes close, but can fail spectacularly under some circumstances.
Electronic flash guns pump out clean white light, but it’s not “natural” light because parts of the spectrum are missing.
Clean mid-day white light in Queenstown, New Zealand, 2008.
A little bit of trivia – daylight colour temperature varies with latitude. At the equator mid-day light is slightly “warm” as we approach the poles, north or south, the light becomes progressively “cooler.” In the film days colour film was calibrated for the needs of the main market for a particular film type. Agfa colour film was balanced for northern latitudes to warm up the cool light.