What does 'pressure gradient' measure?

The pressure gradient is a fundamental concept in meteorology that refers to the change in atmospheric pressure over a horizontal distance. Specifically, it quantifies how pressure changes as you move from one location to another horizontally. This measurement is crucial because it drives wind — air moves from areas of high pressure to areas of low pressure, and the rate or strength of this movement is determined by the steepness of the pressure gradient. A steep pressure gradient typically results in stronger winds, while a gentle gradient is associated with light winds.

In summary, the correct choice accurately reflects the definition of pressure gradient, which is essential for understanding wind patterns, weather systems, and many other meteorological phenomena.