New Kid's Questions #4 - Water temperature vs bouyancy

[ubp_sanity]

Maybe I should have put a smiley at the end of the sentence where I mentioned the different tanks and the fact that it's different water types.

However, I was wondering if I was going to the east coast what I'd need to add to compensate for the salinity of the ocean, definitely not going with the Caribbean setup there

 

[Jim Lapenta]

One item I have noticed with regard to water temps is in fresh water going between thermoclines will have an effect on buoyancy. Small but when properly weighted it is defintely there. For example one lake where we do our training is very warm. 86 at the surface yesterday. Sometimes there are what I call pockets of colder water at the same depth as warmer water. I think this is due to the way the power plant is discharging the heated water. It creates these pockets or sometimes currents of colder and warmer water at equal depths. Hitting one of these pockets can drop the temp as much as 4-5 degrees.

I definitely notice a reduction in the volume of air in the BC if in them for any length of time. By the same token coming up from cold water to warm in addition to Boyle's law I believe that Charles law also comes into play. This is from my own careful observation of ascending through different depths in water with thermoclines and water without. I know I put less gas in the wing when coming up into warm water from cold than I do when ascending from water where the bottom temp is the same as the surface.

In some of the quarries where we have serious thermoclines new divers have to be very careful when the warm water as well as the reduction in depth hits the air in the BC. Heated air expands more rapidly.