Atmospheric Pressure: This is the pressure exerted by the weight of air in the atmosphere of Earth, typically measured in atmospheres or pascals.
Hydrostatic Pressure: This refers to the pressure that any fluid in equilibrium exerts due to gravity. It increases with depth as more fluid weight is added.
Pressure Gradient: This term describes how pressure changes over distance. If there's a big change over a short distance, that's a steep gradient.