Thanks. The Wikipedia entry I took this from is: https://en.wikipedia.org/wiki/Bedford_Level_experiment
It claims that this effect (light rays curving downward at a rate equal to the mean curvature of the Earth's surface) can "explain" why long water stretches (like in the Bedford Level...
Wikipedia states that:
"If the measurement is close enough to the surface, light rays can curve downward at a rate equal to the mean curvature of the Earth's surface. In this case, the two effects of assumed curvature and refraction could cancel each other out and the Earth will appear flat in...
You will need higher moments - the pairwise correlations are not enough for n>2. Look into Teugels (1990) ‘Some Representations of the Multivariate Bernoulli and Binomial Distributions’, where he provides a formulation for a general multivariate Bernoulli with dependencies, for n dimensions...