The change in pressure measured across distance is called a pressure gradient. The difference in pressure results in a net force that is directed from high to low pressure, and this net force is called the pressure gradient.
Winds blow from higher to lower pressure due to the pressure gradient force.
As the ship sunk lower, it encountered greater pressure from the water as compared to the normal atmospheric pressure in the bridge. The difference in pressure grew as to overcome the strength and fastenings of the glass. It pulls air from high pressure to low, creating winds which in turn push the water.