The change in atmospheric pressure per unit distance. The greater the change in pressure per unit distance, the stronger the pressure the pressure gradient and the stronger the wind.
The rate of decrease of pressure per unit of horizontal distance. On the same chart, when the isobars are close together, the pressure gradient is steep. When the isobars are far apart, the pressure gradient is weak.
(In meteorology, also called barometric gradient.) The rate of decrease (gradient) of pressure in space at a fixed time. The term is sometimes loosely used to denote simply the magnitude of the gradient of the pressure field.