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6: Atmospheric Forces and Wind

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    Introduction

    Wind is simply air in motion. In meteorology, when discussing wind, we are primarily concerned with its horizontal speed and direction. For example, if you hear a report of a west wind at 15 mph (24 km/h), that means the horizontal winds will be coming from the west at that speed. Although we cannot actually see the air moving, we can measure its motion by the force it exerts on objects. We use a wind vane to indicate the wind's direction and an anemometer to measure the wind's speed, as shown in Figure \(\PageIndex{1}\).

    A wind vane and a cup anemometer on the roof of a building.
    Figure \(\PageIndex{1}\): A weather station at a water treatment plant consisting of a wind vane and a cup anemometer. (CC BY-SA 3.0; William Demchick via Wikimedia Commons)

    Newton's first law of motion states that an object at rest will remain at rest unless acted upon by an external unbalanced force. A Force is a pull or push that changes the resting state, motion, or direction of an object. Thus, as with all moving things, wind is caused by a net force acting on air. In this chapter, we'll examine the forces that act on air to cause winds.

    Learning Objectives

    By the end of this chapter, you should be able to:

    • Define wind and why it occurs
    • Describe the four physical forces that can act on a parcel of air
    • Draw force diagrams for geostrophic wind, gradient wind, and wind in the atmospheric boundary layer (ABL)

    • 6.1: Wind
      This page outlines five main forces affecting horizontal wind dynamics: the pressure gradient force, which drives wind from high to low pressure; advection, the wind's momentum transport; centrifugal force influencing curved wind paths; the Coriolis force from Earth's rotation that alters air movement by hemisphere; and turbulent drag that decelerates wind in the atmospheric boundary layer.
    • 6.2: Force Balances
      This page covers the force balances affecting horizontal wind speed and direction in the atmosphere, emphasizing geostrophic balance involving pressure gradient and Coriolis forces in large-scale winds. It also addresses gradient winds with centrifugal forces on curved isobars, atmospheric boundary layer winds where friction impacts speed, and cyclostrophic winds in smaller phenomena like tornadoes, which balance centrifugal and pressure gradient forces.
    • 6.3: Exercises
      Some exercises to review the topics covered in this chapter.

    Thumbnail: 500 mb height contours by NOAA is in the Public Domain

    This page titled 6: Atmospheric Forces and Wind was last modified on Wed, 02 Sep 2026 04:08:18 GMT and is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Neel Desai and Alicia Mullens.