Which criteria must be satisfied for variable visibility to be reported?

Variable visibility is reported when visibility conditions are not stable and fluctuate significantly within a short period. Specifically, for variable visibility to be reported, the criterion states that visibility must be less than 3 miles and show rapid changes, increasing or decreasing by 1/2 mile or more.

This is important because variable visibility represents conditions affecting a pilot's ability to navigate safely, as visibility is unpredictable and can change quickly. Reporting such conditions is critical for safety in aviation and other operations that depend on visibility, as it alerts pilots and meteorologists to the potential for rapidly shifting weather conditions that could impact flight paths.

In contrast, the other options do not meet the criteria for reporting variable visibility. For example, options that specify a constant visibility of 3 miles or greater do not reflect the fluctuation needed to classify visibility as variable. The expectation for stable conditions does not align with the definition of variable visibility, which necessitates noticeable changes in the visibility measurement.