How is a trough depicted on a GFA?

A trough on a GFA (Graphic Area Forecast) is represented by a single purple line. This depiction clarifies the location of a trough, which is an elongated area of low pressure characterized by distinct weather patterns. In meteorology, identifying troughs is crucial because they often indicate the potential for developing weather phenomena such as cloud formation, precipitation, and shifts in wind patterns.

The use of a single purple line helps pilots and meteorologists quickly recognize the troughs on the forecast maps, facilitating effective planning and decision-making regarding flight operations. Furthermore, understanding how troughs are represented allows pilots to anticipate possible weather changes that could impact flight safety.

Other options depict different meteorological features, which may include fronts or other atmospheric phenomena, but they are not correct for identifying a trough specifically. This understanding aids in accurately interpreting weather forecasts essential for safe flying.