Visibility vs Illumination

[miketsp]

I just finished reading an article in a dive-mag which states that "visibility in caves is zero, which is why you need to have a good light source". The author is a nationally famous technical diver.

I would have preferred to see "natural illumination in caves is zero..."
Anyone else find this strange?

 

[El Orans]

The vis is always zero when doing night dives...

 

[The Kraken]

Interesting semantics question . . .

I tend to agree with you, Mike.

While the illumination,or the lack thereof, in a cave makes it impossible for us to see, given our physiological makeup, other creatures that are adapted to nocturnal existence can see very well. So the visibility is not affected.

the Kraken

 

[Jamdiver]

I just finished reading an article in a dive-mag which states that "visibility in caves is zero, which is why you need to have a good light source". The author is a nationally famous technical diver.

I would have preferred to see "natural illumination in caves is zero..."
Anyone else find this strange?

I tend to agree with you there Mike.

To most divers a visibility of zero implies high turbidity and large quantities of particulate matter in the water making it difficult to even see your guages.
That however is not what I think he was referring to in the article.

It would have been better stated if the author explained for those who are not familiar to cave diving that because it's an overhead environment there is no natural illumination from the sun so in essence visibility is zero due to the lack of natural light..
But since cave divers dive with a minimum of 3 lights? I believe, I don't foresee that being a problem.

Semantics I suppose, some people just word things differently.

 

[Walter]

Did you understand the concept? If you did, he got his point across. I would've worded it differently, but communicating the concept is what is important.

 

[DA Aquamaster]

Did you understand the concept? If you did, he got his point across. I would've worded it differently, but communicating the concept is what is important.

That was the point of his complaint. He understood it because he knew enough about low viz diving and caves to understand what the author was talking about. It's very likely that many other readers, knowing little about low visibility diving and not much about caves, may conclude that that caves have "zero visibility" for reasons not entirely related to a lack of natural light and/or may conclude that enough illumination will some how cut through turbid zero visibility water instead of just turning black zero viz into brown zero viz.

And I'm pretty certain that anyone who ever passed Freshman Comp is going to conclude the author is probably either the professional writing equivalent of a functional illiterate or an idiot.

Communicating the concept IS what is important, and the author did an incredibly poor job of it. It's probably a good example that just being a nationally known technical diver is not enough to make you a good writer.