What is the criterion for moderate rain?

The criterion for moderate rain is defined by the presence of individual drops that are clearly identifiable alongside observable spray above hard surfaces. This indicates that the rain intensity is sufficient to create not only visible droplets but also the spray effect, which arises from the impact of those drops hitting the ground or other surfaces.

This differentiation is significant in aviation weather reporting as it directly impacts visibility and operational conditions. Moderate rain can affect flight operations more noticeably than lighter rain or drizzle, warranting its distinct classification in weather reports.

Other options describe conditions that do not correspond to the intensity and characteristics associated with moderate rain. Individual drops being identifiable without spray, continuous drizzle, or droplets that merely coat surfaces convey lesser intensity or different falling rain types rather than the moderate category, which combines both visibility of droplets and the resultant spray effect.