Visibility is the greatest distance at which an object can be clearly seen and identified. It is reduced by fog, heavy rain, snow, dust, smoke, or haze. Official observations report visibility in meters or miles.

Aviation depends critically on visibility for takeoffs and landings under visual rules. Road safety also declines sharply when visibility drops. Automated sensors and human observers both measure it, often using known landmarks or light sources at night.

Sudden reductions in visibility can occur with the onset of fog, heavy precipitation, or dust storms. Forecasts of visibility are included in aviation and marine weather products. In some regions, seasonal haze or smoke from wildfires can keep visibility reduced for days.

Clear air with high visibility is appreciated by pilots, photographers, and anyone enjoying a distant view.