condensation
This is the valve from the propane canister to our little gas stove. The water vapor in the air was condensing on this because, I suppose, the gas passing through it was cold. (I thought compression made gasses hot. Anyone?)
The point of this photo was to try my hand again at a close up using the macro function on my frustrating camera. I guess my conditions were a bit more controlled here. Even light. No distance behind the subject for the camera to focus on.
It’s not really crisply focused. But I suppose it’s good enuf for blog work.
December 20th, 2012 at 6:51 am
Compressing gases makes them heat up. When the compression is released they get cold. That’s essentially what’s behind air conditioning.
December 20th, 2012 at 6:55 am
The technical explanation can be seen with the Ideal Gas Law
PV=nRT or Pressure x Volume equals (n) moles of gas x (R) gas constant x Temperature.
When you reduce the pressure by opening the valve, temperature also needs to reduce to keep the equation equal.
December 20th, 2012 at 7:41 am
Yeah, what he said…
December 20th, 2012 at 8:44 am
Uh, yeah…I’m with Mark…
Momadness
December 20th, 2012 at 8:52 am
Can you tell what part of the frame the camera is actually using for focus? I’m sure it would try to get the center in focus in most, if not all cases. That seems to be the case here. On the other hand, although I can’t tell what’s behind the gas hose, that seems to be in good focus. What camera are you using?
December 25th, 2012 at 12:57 am
Expansion of a gas is endothermic. You can get frost on a scuba tank valve if you crack it wide open and let the compressed air blast out.
Merry Christmas!