Session 4: Horizontal Acceleration

Horizontal Acceleration (dV/dt)

Friction, Coriolis, and the pressure gradient forces act on any parcel of air. If these forces balance each other, then the air parcel will maintain a constant velocity (no change in speed or direction). However, if the three forces do not balance each other, then the air parcel is said to experience acceleration, or a change in speed or direction over time. The parcel may accelerate or decelerate.

The acceleration is itself a net force, and air flow shifts toward its direction. It influences the air flow just as the other forces do, even though it is really a product of the other forces acting on the parcel. When we combine these forces, we get the following:

This equation governs air movement in the horizontal direction. What would happen if we took away friction? The result would be geostrophic flow, our next topic.

On to Geostrophic Wind

Back to Friction

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