This is from the loop dynamics topic but I think it makes a great segue into a topic Paul and I have discussed a number of times.James9118 wrote: ↑Wed Nov 29, 2023 8:19 pmAt a cliff face I've visited a number of times in New Mexico (Sandia Peak) you could stick your arm out over the edge and feel the rush of air directly upwards (depending on the direction the wind was coming from). It was also the case that as the air cooled as it was travelling upwards the moisture in it would condense into a mist, thus you could stick your hand into an upward shower of mist. Paragliders would often launch from the same place.Paul Arden wrote: ↑Wed Nov 29, 2023 5:48 pm
I used to park my truck on the side of a cliff overlooking the Waiau River in Fiordland, New Zealand. And in the evening I would stand on the roof and play with my maximum carry. There was music involved and red wine.
The point is I used to throw the forward cast downwards. Now it may have been my perspective but there was a big difference between the loop unrolling downwards, and loop straight and free fall.
I’ll find a cliff to reenact this entertainment and try to film it this time.
The same thing happens with a crosswind (I believe) so I don’t think it’s loop lift.
Paul tells me that when casting in high humidity and especially in fog that he can't cast as far - a difference of 10 feet. I know it's anecdotal but when someone spends as much time as Paul does practicing and pays as much attention to anything that could be affecting his cast I tend to listen to what he says.
The problem is that the science I've read tells me that it should be the opposite.
I'm sure we've all seen the formula for form drag:
Force of Drag = 0.5 ρACdv^2
in which ρ represents the density of air.
This formula tells us that the drag force is directly proportional to the density of air. Intuitively we think that humid air is more dense than dry air because water is denser than air, right? The problem is that water vapor is less dense than air so humid air is less dense than dry air. That should mean that there is less drag on the line in humid air and, therefore, it should go farther.
So, assuming Paul is correct about the effect of humidity on his cast, there must be something else affecting his cast and I have no idea what it would be. (i'm ruling out arthritis for now... )
So, two questions:
1. Has anyone else noted a similar effect?
2. Does anybody have any idea what the reason for this would be? The only other thing I can think of is that humidity affects the line itself. Maybe that's farfetched but we know that monofilament nylon absorbs water which results in it becoming weaker after it has been submerged for some time. If fly line has been sitting in higher humidity could it absorb some of the humidity affecting its castability? Given the recent discussions about losses in fly line during the cast I'm wondering if something that affects the fly line itself and causing additional losses could be a cause? Would the dynamic test Torsten described in another thread help to confirm or deny this?
Paul also tells me that he can cast farther in higher temperatures as well. Something else to consider - what other air condition factors could affect the cast?