In the context of wind, what is the primary characteristic of geostrophic wind?

The primary characteristic of geostrophic wind is that the Coriolis force balances the pressure gradient force, leading to a flow that is parallel to the isobars rather than crossing them. This balance occurs in the upper atmosphere where friction is minimal. In the context of geostrophic wind, the direction of this flow is dictated by the orientation of the pressure gradient and the Coriolis effect caused by the Earth's rotation. In the Northern Hemisphere, this results in low-pressure systems being located to the left of the wind direction when looking downwind.

This is significant because it highlights the distinct behavior of winds in different layers of the atmosphere. Unlike surface winds, which are affected by friction and can cross isobars, the geostrophic wind represents a more idealized flow that exists in the absence of such influences. This makes option C the correct response as it accurately describes the balance of forces at play in geostrophic wind.