ic ▁parameters ▁due ▁to ▁tur bul ence ▁and ▁other ▁atmos pher ic ▁perturb ation ▁phen omena . ▁ ▁It ▁is ▁available ▁in ▁computer ▁code ▁written ▁in ▁Fort ran . ▁ ▁The ▁G RAM ▁series ▁also ▁includes ▁atmos pher ic ▁models ▁for ▁the ▁plan ets ▁Ven us , ▁Mars ▁and ▁Ne pt une ▁and ▁the ▁Sat urn ian ▁moon , ▁T itan . ▁ ▁Ge op ot ential ▁alt itude ▁ ▁Gra v it ational ▁acceleration , ▁g ( z ), ▁decre ases ▁with ▁alt itude ▁since ▁moving ▁up ▁means ▁moving ▁away ▁from ▁the ▁planet ' s ▁center . ▁ ▁This ▁problem ▁of ▁decre asing ▁g ▁can ▁be ▁de alt ▁with ▁by ▁defining ▁a ▁transformation ▁from ▁real ▁geometric ▁alt itude ▁z ▁to ▁an ▁abstra ction ▁called ▁" ge op ot ential ▁alt itude " ▁h , ▁defined : ▁▁ ▁h ▁has ▁the ▁property ▁▁ ▁where ▁▁ ▁Which ▁basically ▁says ▁the ▁amount ▁of ▁work ▁done ▁lif ting ▁a ▁ ▁test ▁mass ▁m ▁to ▁height ▁z ▁through ▁an ▁atmosphere ▁where ▁gravity ▁decre ases ▁with ▁alt itude , ▁is ▁the ▁same ▁as ▁the ▁amount ▁of ▁work ▁done ▁lif ting ▁that ▁same ▁mass ▁to ▁a ▁height ▁h ▁through ▁an ▁atmosphere ▁where ▁g ▁mag ically ▁remains ▁equal ▁to ▁g 0 , ▁its ▁value ▁at ▁sea ▁level . ▁▁▁▁ ▁This ▁ge op ot ential ▁alt itude ▁h ▁is ▁then ▁used ▁instead ▁of ▁geometric ▁alt itude ▁z ▁in ▁the ▁hydro static ▁equations . ▁ ▁Common ▁models ▁ ▁The ▁US ▁Standard ▁At mos phere ▁is ▁one ▁of ▁the ▁most ▁common ▁models ▁