A Venturi nozzle drags air into the stream at the throat, and the result is a column that is roughly half air by volume. It is white, opaque, and holds its shape in daylight at a distance where a clear jet has disappeared. This is the effect for a civic set piece seen from across a square, and it is almost always the wrong effect for an interior.
It needs a submerged nozzle with a specific water level above it — usually 60 to 120 mm depending on the family — because the aeration slots have to be flooded to work. Drop the basin level by 30 mm and the column collapses to a splutter. On sites with heavy evaporation this is the failure the client photographs and sends you, so the level control has to be honest and the top-up valve has to be sized for the worst August day, not the average one.
The column is heavy and stands up to wind well; the spray it sheds does not, and that spray is the thing that wets the paving. It is also the loudest thing in the catalogue, in a low, gravelly band that carries. We do not put it within 30 m of a residential window without a night programme that turns it off.