Crab - you may be right, but I'm not convinced
The weight of the aircraft does not impinge on the surface so only the weight of air above that point is acting on the surface
Are you suggesting that the downwash holding us up (newton) has no effect of 'pressing down' on the surface before it's forced to diverge?
The rotor downwash is not constrained by anything
Except the weight of the rest of the surrounding atmosphere (ambient pressure), and the mass of air it must displace...(quite significant)
The rotor imparts an acceleration to the air in order to create thrust to balance the aircraft weight
Agreed
the air accelerates downwards because of the rotor and outwards because of the ground - still no requirement for a pressure increase below the rotor
So how does the stationary ground cause this air to change direction if it's not a build up of pressure?