Moon Cycles on Sandig Skaa

What is a moon cycle on Sandig Skaa?

This question has come up a few times as Keegan and Tana have both reflected on the timing of different events over the course of moon cycles. 

The books (Secrets of the Desert, Into the Den, Sand & Stone) mention several times that a moon cycle is 30 days... but what exactly does that mean?

My editor has convinced me to include a more thorough explanation (though it will still be short) in Into the Den, but if you can't wait (or if you want the super awesome, l...