@tim-hobson
There are a bunch of interesting things there that I will definitely look into. Thanks for making so many tutorials!
But allow me to better demonstrate the issue to show why disabling and enabling the light cannot be the solution for a sunrise/sunset.
here, at the beginning stages of the sunrise, yes, disabling the light would solve the problem with the ground reflecting or letting through some light.
Here if the light were disabled to solve the light on the ground, the sky sunrise effect would not be present.
By now, with the light still disabled to solve the lit ground, this entire skylight effect is not there.
And now finally way later it the ground gets lit properly.
as you can see in this last screen shot, the light does not shine through the landscape when it is pointing directly up at it from the bottom, i.e. nighttime (those few brights things you see are foliage being lit from the bottom
