Changes

: [[Fluid Pressure|Pressure]] in a [[fluid]] is due to the [[weight]] of the [[fluid]] above the [[object]]. As an [[object]] gets higher, there is less [[atmosphere]] above that [[object]].

: The reduction in [[pressure]] is related to the [[density]] and motion of [[particle]]s in the [[atmosphere]].

*The [[atmosphere]] is less [[density|dense]] - Less frequent [[collision]]s between the [[particle]]s and the surface of the [[object]].

*The [[temperature]] is colder - [[Particle]]s move more slowly leading to less [[collision]]s and the [[collision]]s which do happen occur with less [[force]].