The vertical axis on the left is sync speed, in m/s.
On the top there are two horizontal axes, one for glider air speed, and another for glider
ground speed. With no wind, the two axes are in the same position.
You can switch between Km/h and mph.
The polar curve is the set of points in this plane that are possible for the glider.
Position on the curve depends on the braking or acceleration controls the pilot engages.
In this simulation the wind is aligned with the glider direction,
that is headwind or tailwind. Other configurations, like lateral or cross wind or vertically
moving air (lift/sink) - maybe in a future version.
Identify the key points on the polar curve. Click the labels of each point on the graph.
Change the wind speed to see how it affects best glide.
A negative value is headwind, positive one is tailwind.
Notice how the air speed X axis moves together with the polar curve.
If the air moves, the glider still flies the same relative to the air,
but the ground speed is different.
The glide ratio indicated is for the ground speed, this is the one that you care about.
You have a headwind of 15 Km/h
See how best glide position has moved lower and to the right on the curve.
For best glide you now apply some speedbar.
You will sink faster but with greater horizontal speed.
You have a tailwind of 15 Km/h
Apply some brake to improve your glide.