The momentum of a high-velocity jet will carry
the gas higher than the point of release, resulting in a much higher effective release height. If
the gas has a density less than air, the released gas will initially be positively buoyant and will
lift upward. If the gas has a density greater than air, then the released gas will initially be negatively
buoyant and will slump toward the ground. The temperature and molecular weight of
the released gas determine the gas density relative to that of air (with a molecular weight of
28.97). For all gases, as the gas travels downwind and is mixed with fresh air, a point will eventually
be reached where the gas has been diluted adequately to be considered neutrally buoyant.
At this point the dispersion is dominated by ambient turbulence