Final answer:
A 30 knot wind gusting at 40 would be depicted on a GFA chart with three full barbs to indicate the sustained wind speed and a notation for gusts, showing the gusting speed beside the station model.
Step-by-step explanation:
The question of how a 30 knot wind gusting at 40 would look on a Geographical Forecast Area (GFA) chart is in the realm of aviation and meteorology, both of which are rooted in physics. A GFA chart is used to inform pilots about weather conditions, including wind speed and direction. Wind speeds on these charts are typically represented by barbs or flags. A full barb indicates 10 knots of wind, a half barb suggests 5 knots, and a triangular flag represents 50 knots. When wind is gusting, the term 'gusting to 40' would often be written beside the station model. Therefore, for a 30 knot wind gusting at 40, you would see three full barbs and the gusting speed written next to it.