Loyd Jones and H.R. Condit wrote a paper for the Journal of the Optical Society of America in 1948 titled Sunlight and Skylight as Determinants of Photographic Exposure. It was published in two parts and combined is about 80 pages. It would not be an exageration to say this is the ultimate source for everything discussed on this thread. In addition, I don't think it's a coincidence that the first ASA standard of light meters was also release the same year this paper was published and that Jones was the chair on the light meter committee.

On the subject of light meters, the basic balanced exposure equation is:

A^2/T = BxS/K

A= aperture
T = shutter
B = luminance in footlambarts
S = film speed
K = constant

Here's the Sunny 16 example

16^2/ 1/125 = 297x125 / 1.16

this reduces down to

256/256 = 1