This rapid weakening was likely due to the hurricane encountering an area of higher wind shear, cooler sea surface temperatures, and dry air entrainment.
Encountering dry air entrainment and vertical wind shear, Durian weakened slightly at first, but slowly began to reorganise and restrengthen as it neared Vietnam.
It then weakened as wind shear increased and dry air entrainment occurred.
The storm started to rebuild central convection on July 31, yet troughing and dry air entrainment degraded outflow over the southern portion.
It weakened to a tropical storm due to cool air entrainment into the circulation on September 11, but on September 12 it was able to re-strengthen.
However, vertical wind shear and dry air entrainment weakened Gordon back to a tropical storm later that day.
Examples of localised aeration include air entrainment by plunging water jet and at hydraulic jump.
When this happens, the jump can be accompanied by violent turbulence, eddying, air entrainment, and surface undulations, or waves.
The air entrainment occurs in the form of air bubbles and air packets entrapped at the impingement of the upstream jet flow with the roller.
However, the thunderstorm activity decreased markedly on September 6, primarily from dry air entrainment, and it weakened to tropical depression status for the last time.