Narrowband images are also called "false color".  Color is used in astronomy to convey important information on the composition of astronomical objects. We take advantage of the brain's ability to discern color differences to convey information on the relative distribution of the components of nebula and other narrowband targets.

Since my particular location is plagued by light pollution and frequent clouds, I prefer to take narrowband images. I can take narrowband images on any clear night as long as the moon is not right on top of the object.  They are not affected by light pollution. Unfortunately targets that consist mainly of stars (galaxies and star clusters) can not be photographed with narrowband filters. I use a different technique for them.