What causes water to rise inside the intake hose during drafting?

The rise of water inside the intake hose during drafting is primarily due to the greater pressure outside the hose. When drafting, the pump creates a vacuum within the hose, lowering the pressure inside. This reduction in pressure allows the atmospheric pressure, which is greater than the pressure inside the hose, to push water up from the source into the hose. Essentially, the higher atmospheric pressure exerts force on the surface of the water outside the intake, compelling the water to move into the area of lower pressure inside the hose.

In this context, while the weight of the water outside the hose does play a role in the dynamics of fluid dynamics, it is not the primary cause of water rising into the hose. Similarly, air pressure inside the hose, which is reduced when vacuum is created, does not contribute positively to raising the water. Heating of the water does not influence the drafting process significantly either; rather, temperature changes can impact density and behavior of fluids overall, but they do not directly cause the water to rise in this specific scenario.