Question about diving at altitude

[Mad_diver]

Ok, I'm not being a smart arse, just curious. I thought your ears popped while driving up a mountain because the air pressure was increasing. Although the air seems thinner up there, so that makes sense that it's decreasing as you rise. So why do you have to equalize when going up in a plane or on a mountain?

When you are moving up in elevation, there is LESS pressure on your ears. The air present in your ears is at a higher pressure than the surrounding air (Like the balloon filled at 50 feet then sent to the surface). As you ascend to higher altitudes (Mountains /large hill/ or plane) the air continues to expand and equalizes it self. (Just like when you surface from a dive.)
It's not really equalizing (Like on decent) because you're not adding pressure to your air spaces. The air is escaping. It does feel similar though, I guess.

Mad_diver

 

[mrobinson]

Too bad... There's alot of joking around on this thread and no see it!

 

[boomx5]

If you're diving Air at that altitude and go THAT DEEP, I'd be willing to bet you'd be bent befor you hit the surface.

To identify the risk, we need to know HOW long you were at that altitude before you made the dive. (There is a certain amount of off gasing that happens when you arrive). Also we'd need to know how long you stayed at that depth and what breathing gas you were using.

Driving home isn't any big deal (assuming you make to the surface) as long as your house is at a lower elevation than the dive site.

This is ALL covered in the PADI Altitude course.

My question was partly a troll to see what kind of answers I'd get. We do a lot of diving in that range at altitude exactly like I stated in my question...oh, and we don't dive air in those ranges. By the way, we do have to travel over 1,000' additional in altitude before we descend back to sea level.

 

[divetahoe]

oh, and we don't dive air in those ranges. By the way, we do have to travel over 1,000' additional in altitude before we descend back to sea level.

Popping (so to speak ) over Echo Summit, eh?

 

[boomx5]

Popping (so to speak ) over Echo Summit, eh?

Huh? I'm sorry I missed the joke..it's been a very long day.

 

[Kriterian]

When you are moving up in elevation, there is LESS pressure on your ears. The air present in your ears is at a higher pressure than the surrounding air (Like the balloon filled at 50 feet then sent to the surface). As you ascend to higher altitudes (Mountains /large hill/ or plane) the air continues to expand and equalizes it self. (Just like when you surface from a dive.)
It's not really equalizing (Like on decent) because you're not adding pressure to your air spaces. The air is escaping. It does feel similar though, I guess.

Mad_diver

Ok, thanks for the explanation. I went to the mountains of NC (Blueridge) when I was younger, and I just remember having issues going up the mountain but none coming down. I guess I was getting this confused with what I knew in my heart and scientific mind, that pressure was less at altitude. It makes sense now that I'm diving because I find equalizing on the way up from depth (cracking and popping) more noticable than going down.

Although I'm still not sure why I have to chew gum or swallow while lifting off in a plane but have no issues coming back down.

 

[Atticus]

I frequently drive from my home in Reno (4400' elevation) to Tahoe (6229' elevation), dive to 200' (on trimix, thankyou very much), and then drive back home to Reno.

I don't wait 12-24 hours before diving, but I do take my ascent from Reno into account. I also use modify my decompression schedule to take into account the reduced surface pressure. I do this whether I am using a preplanned profile or if I am using a "tic tac toe" deco schedule (deco on the fly).

There's some conservatism in decompression theory to account for differences in physiology, conditions, etc. We also try to set the bar such that people aren't getting hurt on a regular basis. By not adjusting for altitude you increase your risk factor. It doesn't mean you're going to get hurt, just that you have less conservatism than normal.

Too many deco training sessions focus on the "it's only 7' of water difference in pressure" (adjust for your altitude). This is an oversimplification which leads to divers taking more risk than when they dive at sea level.

To answer the original posters question, there are altitude courses available, but honestly for the types of dives you're doing (one dive per day, 30-40', using a computer, 4000-5000' elevation) you're unlikely to get into trouble. Take the course if you'd like to learn some of the science behind it or if you want to be an altitude table wiz. An instructor worth their salt will teach you some fun physics.