In the diagram on the right, the two waves cancel each other out creating a flat surface however this is a highly simplified version of events.

The waves that you sent out are canceling the waves of the mage-storms, but-only to a point.

High waves canceled ferry service to Staten Island.

These waves will cancel periodically along the line causing nulls every half wavelength.

In the end the advanced wave cancels itself OUt.

Replies: Dark only happens if waves cancel.

When the second wave reaches the surface, the two waves combine and cancel each other out due to the phenomenon of interference.

So it is a half wavelength out of phase with the first wave when they combine, and the two waves cancel.

Therefore the waves will cancel (subtract) and the resulting light intensity will be weaker or zero.

Often enough, these extra waves cancel each other out for no power, due to traveling in opposite directions.