What should be observed to assess the weight of weather conditions in terms of visibility during approach?

To assess the weight of weather conditions in terms of visibility during approach, it is essential to observe both visibility and ceiling. Visibility refers to the clarity of the air and how far one can see, which is crucial during approaches as it directly affects the pilot's ability to navigate and land safely. Ceiling, defined as the height of the lowest layer of clouds above the ground, also plays a significant role since it determines how low a pilot can safely operate during an approach.

Relying solely on ceiling would overlook critical visibility factors that can impede safe landing and navigation, such as fog or heavy rain. While observing fog density and type of precipitation are indeed important, they provide more specific information about visibility eventually factored into the overall assessment rather than serving as standalone indicators. Therefore, considering both visibility and ceiling together gives a comprehensive understanding of the weather conditions impacting an approach.