If visibility is reduced from 12 miles to 7 miles due to mist, light snow, and smoke, what is the minimum entry for column 9?

In the context of aviation weather observations, column 9 typically refers to the visibility conditions affecting flight operations. When visibility drops, as in this case from 12 miles to 7 miles, it’s important to note the weather phenomena causing this reduction.

The correct entry indicating that visibility is reduced due to mist, light snow, and smoke can be effectively encapsulated by the descriptor for light snow, denoted by the symbol for light snow (-SN). This symbol conveys the fact that snow is contributing to the reduction in visibility, which is significant for pilots and air traffic control as it directly impacts safety and operational decisions.

While mist (BR) and smoke (FU) are also important factors in visibility reduction, the choice to represent the weather observation primarily with light snow (-SN) aligns with the requirement to note significant weather phenomena impacting visibility. Other combinations that include mist and smoke alongside light snow can be seen in other answers, but they may introduce unnecessary complexity or less focus on the most dominant weather condition influencing visibility at that moment, which is light snow.

Thus, the selected entry provides the most straightforward representation of the observed conditions affecting visibility in the reporting scenario.