 I'm going to use this interactive force diagram to show you how wind speed can be affected by factors other than the pressure gradient force or friction. This tool allows me to adjust the strength of the pressure gradient force, the Coriolis force by adjusting latitude, and friction. We'll start with a partial and geostrophic balance, which means that we'll ignore friction for a moment. This parcel would move parallel to local isobars, with lower pressure on its left. That's the balance of the pressure gradient force and the Coriolis force. We know we could increase the parcel speed by increasing the pressure gradient force, and that's marked by the velocity vector getting larger to indicate a faster speed. But determining wind speed is more complicated than simply thinking about the pressure gradient force. If I hold the pressure gradient force constant and change latitude, look what happens to the velocity vector. The velocity vector gets larger equating to faster wind speeds at lower latitudes, and gets smaller equating to slower wind speeds at higher latitudes, all without changing the pressure gradient force. This occurs because the Coriolis force depends on both latitude and a parcel's velocity, so there are two ways to boost the Coriolis force, by increasing latitude or increasing wind velocity. But if you're analyzing parcels at a fixed latitude, then the only way to increase the magnitude of the Coriolis force is to increase velocity. Therefore at lower latitudes, for parcels to achieve geostrophic balance, air parcels must move faster than they would at higher latitudes in order to compensate for latitude's smaller contribution to the overall magnitude of the Coriolis force. This holds true even if we activate friction, with friction added to the mix, our parcel is no longer in geostrophic balance and crosses local isobars in toward lower pressure. But if we hold friction and the pressure gradient force constant, the velocity increases at lower latitudes and decreases at higher latitudes. The practical application of this relationship is that if all other forces are equal, cities at different latitudes will experience different wind speeds.