When prevailing visibility varies rapidly between one and one-half to two and one-half miles, how is it reported?

The correct way to report prevailing visibility that varies rapidly between one and one-half to two and one-half miles is to use the format that includes both a visibility value and a remark indicating the variation. In this case, the notation "2SM RMK VIS 1 1/2V2 1/2" effectively communicates the average visibility along with the range of variation.

This format adheres to meteorological reporting standards, capturing important details such as the average visibility (2 statute miles) and the variable aspect (the visibility fluctuating between 1.5 and 2.5 statute miles). Such precision is crucial for understanding changing weather conditions, especially in aviation or other safety-sensitive operations.

The other options lack the specificity required for such reports. For instance, merely stating “1 1/2 - 2 1/2SM” gives a range but does not indicate which value is the average visibility or that there is significant variability. The format “VAR 1.5-2.5SM” condenses the information but does not establish a clear average value for the visibility. Lastly, “1.5-2.5 miles” is too vague and does not comply with recognized reporting formats in meteorology.