Vacuum in the manifold drops as engine demand increases. If you use ported vacuum you always have a vacuum signal. If you want to make adjustments it can be done using the advance pot on the distributor when you use ported vacuum.
The decreasing or waning phases are when the moon shrinks from the full moon down to the new moon (darkness). As the moon wanes during the 3rd and 4th quarters, this is a good time to prune plants, as the water table is diminishing and so less sap will flow out of the cut ends.
The New Gibbous phase usually last between two and three days before the full moon is exalted. Full Moon. The Full Moon is observed when the Sun, Earth, and Moon are in a straight line and the moon's lighted side is behind the Earth in alignment with the sun. During the full moon phase, the moon rises high off the horizon. At this time, the details of the moon are most visible. Once in a while the moon will orbit on a node.