Snow Goggles vs Bike Goggles
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bails87 wrote:flet©h wrote:Condensation forms on cold surfaces, not hot ones. It forms when the air is warm, not cold.
Right.....so going into cold air with warm goggles wouldn't cause condensation? For example, walking out of a warm bar onto the slopes.
The air inside the goggles is warm, the inner lens surface is cold.
If that isn't happening, what is the point of the double glazing in ski goggles?yeehaamcgee wrote:Actually, sticking on the air con, or opening a window clears condensation quicker from the inside of a windscreen, than hot blowers can
Yep - The condensation clears because the air from the air con is relatively dry. Therefore it can 'absorb' more water vapor than wet air. The air flow (from the windows and the air con) is also moving past the windscreen, preventing the air near the screen becoming saturated with water vapor and not clearing the screen as quickly. You will notice that you can clear the screen even more quickly by sticking the AC on and also turning the heat up to max. Hot dry air will clear the screen very quickly.
(You can also experience the dry air created by air conditioning as you will get a dry mouth when working in the heavily air conditioned offices you find in hot Asian countries)
The "open windows method" for clearing condensation in also used in ski goggles in the form of venting.
None of this changes the reason the condensation formed in the first place which was the warm air in the car and the cold inner surface of the screen.0 -
erm, not.flet©h wrote:You will notice that you can clear the screen even more quickly by sticking the AC on and also turning the heat up to max. Hot dry air will clear the screen very quickly.
Every car I've had that's had air con, was "intelligent" enough to switch the air con off when you actually wanted was heat.0 -
flet©h wrote:bails87 wrote:flet©h wrote:Condensation forms on cold surfaces, not hot ones. It forms when the air is warm, not cold.
Right.....so going into cold air with warm goggles wouldn't cause condensation? For example, walking out of a warm bar onto the slopes.
The air inside the goggles is warm, the inner lens surface is cold.
If that isn't happening, what is the point of the double glazing in ski goggles?
I just took that to mean the opposite of what you were saying about walking from a warm room to the cold outdoors. Becuase then you'd have cold air on a warm surface, so no condensation. But you said there would be condensation in that situation didn't you?0 -
bails87 wrote:flet©h wrote:bails87 wrote:flet©h wrote:Condensation forms on cold surfaces, not hot ones. It forms when the air is warm, not cold.
Right.....so going into cold air with warm goggles wouldn't cause condensation? For example, walking out of a warm bar onto the slopes.
The air inside the goggles is warm, the inner lens surface is cold.
If that isn't happening, what is the point of the double glazing in ski goggles?
I just took that to mean the opposite of what you were saying about walking from a warm room to the cold outdoors. Becuase then you'd have cold air on a warm surface, so no condensation. But you said there would be condensation in that situation didn't you?
I don't think so. Feel free to read all 4 pages of drivel if you can be bothered to try to prove me wrong.
I think I have been fairly consistent in trying to explain that:
- When outside in the cold you may get condensation on the inside of your goggles. This is caused by the warm wet air inside your goggles condensing on the cold inner surface of the lens. This is called misting and some goggles are double glazed to help prevent this.
- When you come in to the warm you may well get condensation on the outside of your goggles. However nobody cares about this since now that you are inside you can simply take your goggles off. Double glazing won't help prevent condensation in this scenario one little bit.
If you don't believe me simply ask yourself two simple questions. Why are ski goggles double glazed and how will they help me while skiing?
If you still think I'm wrong then by all means go skiing in your bike goggles, you may be OK, take your chances, just don't go to near the edges.0 -
You said:
And I think that's where the confusion is coming from. I thought you were saying that taking something warm into the cold air will cause condensation.Just see what happens when you go [outside] from a warm gondola, chalet, restaurant etc. Even sunglasses will mist up
I think a few other people got confused by it. The fact that you had previously been in the warm is irrelevant, because the condensation only becomes a problem once the goggles are cold. As it happens I don't ski, or wear googles on the bike, so I was asking for clarification, not trying to prove you wrong
I agree when you said cold object + warm air=condensation (that's why glasses steam up when people step off a cold platform onto a packed train, and why the windows steam up when I'm out dogging in winter), but that statement above seemed contradictory to your others, that's all.0 -
That wasn't what I was trying to imply but appreciate it could be misunderstood as maybe its badly worded..bails87 wrote:You said:
And I think that's where the confusion is coming from. I thought you were saying that taking something warm into the cold air will cause condensation.Just see what happens when you go [outside] from a warm gondola, chalet, restaurant etc. Even sunglasses will mist up
I was trying to explain that if you trap enough warm air and then chill the lenses holding the air you will get condensation.0 -
flet©h wrote:
I was trying to explain that if you trap enough warm air and then chill the lenses holding the air you will get condensation.
Which I agree with. I thought you were saying warm goggles + cold air would cause it, but you weren't.
Glad we've got that sorted.
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Seriously mate, give it a rest.yeehaamcgee wrote:
Badly worded, yeah. So badly in fact that it's just plain down right incorrect.flet©h wrote:That wasn't what I was trying to imply but appreciate it could be misunderstood as maybe its badly worded..
The statement is perfectly correct, it just requires the readers to fill in the gaps (badly worded). Gaps which I cleared up in the subsequent posts. However being the internet people were so preoccupied with trying to prove me wrong that they didn't bother to understand what was actually happening and therefore get an answer to the original question.
Imagine I had filled the gaps in for you:Just see what happens when you go [outside] from a warm gondola, chalet, restaurant etc. Even sunglasses will trap some warm air, the lenses will cool quickly in the air, causing the moisture in the warm air to condense on the inner surface of the lens. I.e. they will mist up0 -
I understand about condensation - inside of the sodding car does it every morning!
I believe it works but ho w such a thin layer of air makes a difference surprises me quite alot - (another ride tonight with the stupid glasses steaming up - guess -8 is just too cold for glasses)We're in danger of confusing passion with incompetence
- @ddraver0 -
No , you are....
No i'm not ,you are...
No , i said it first....
etc , etc , etc,
yawn.0 -
Fletch is a bit dumb.
Condensation is caused by cold air, which contains water droplets being warmed by receiving a blast of warm, be it breath or walking into a warm room. The air then condenses due to changes in the form, and mist is formed. Turning the air condition in the car on a cold day for a few seconds to clear the screen solves that. Glasses, just keep riding and it clears itself due to a reduction in the amount of warm air compared to cold air. That's why when you stop with glasses on in the cold, and breath on them, they mist up. Start moving again and their cleared.
You have it backwards fletch.
Smart.0 -
MountainMonster wrote:Condensation is caused by cold air, which contains water droplets being warmed by receiving a blast of warm, be it breath or walking into a warm room. The air then condenses due to changes in the form, and mist is formed. .
that is just plain wrong, the cold air is not warmed, the warm air, such as your breath, hits a cold surface. The air does not "condense due to changes in the form". The warm moisture laden air condenses due to rapid cooling when hitting a cool surface (cool air cannot hold as much moisture as vapour) causing misting
Moving from a warm environment to a cold environment can cause misting in very particular circumstances, such as taking a camera outside from a very warm internal environment to a very cold external environment. Warm air trapped inside the camera will hit the camera lens which has cooled causing misting inside the camera. Think it's pretty rare that that happens though.0 -
Condensation is the reverse of evaporation - it is the transition of gaseous vapour into a liquid, and we most often see this when warm moist air contacts a cold surface. The exact mechanics depends on the partial pressures and temperatures involved, plus the nucleation centres, but the above approximation is good enough for the goggles scenario.
Goggles scenario one: from cold outdoors into warm room. Provided the air is not dry, and the outer part of the lens is cold, then it is very likely water vapour in the air will condense on the OUTSIDE of the lens.
Goggles scenario two: from warm indoors to cold outdoors. Provided there is warm, moist air trapped in the googles, and the outside temparature can cool the inside of the lens sufficiently, condensation can form on the INSIDE of the lens.
But as the first paragraph, it depends on the exact amount of vapours and temps involved, plus cooling and removal of vapour. Some may not see this happen, others will.
Double glazing. A typical window uses two 4mm panes seperated by a 15-20mm gap - the gap usually consists of dehumidified air, an inert gas or even a vacuum. The role of this is to prevent thermal conductivity between the panes. Two small a gap, and the conductivity is still a problem, too large and you get thermal convection currents in the gas. But there is a second, overlooked parts of double glazing - you now have four boundary layers. This allows more coatings, and the designer to reflect or deflect certain wavelengths more effectively.
Also we need to look at anti fog coatings - certain coatings prevent the formation of condensation by altering the phyical properties of the nucleation centre. In addition many higher end goggles have vents to equalize temps and vapour. It just so happens that many double glazed goggles have these other features too - it is not just the double glazing that is working here [if at all], but the other factors.
Personally I think the air gap is too small to have much of an effect, and manufacturers are using the term because people associate it with extra warmth. However extra reflective coatings, anti fog coatings and vents will have an effect, and as before, they seem to come with the double glazing. Until I see figures on thermal conductivity between samples I will stick to this view.0 -
Oh dear. Did you fail your science GCSE or have you not got that far yet?MountainMonster wrote:Fletch is a bit dumb.
Condensation is caused by cold air, which contains water droplets being warmed by receiving a blast of warm, be it breath or walking into a warm room. The air then condenses due to changes in the form, and mist is formed. Turning the air condition in the car on a cold day for a few seconds to clear the screen solves that. Glasses, just keep riding and it clears itself due to a reduction in the amount of warm air compared to cold air. That's why when you stop with glasses on in the cold, and breath on them, they mist up. Start moving again and their cleared.
You have it backwards fletch.
Smart.0 -
PMSL at this thread.
I am boarding on Monday and whilst I know the answer (and the science, see above), just for Fletch, I will walk into L'Arbina in Tignes wearing my goggles and order their famous tartiflette. After eating it, I will put my goggles back on and walk outside.
I will report back with only hard facts, no 'special circumstances', no 'misleading' wording, nothing.
Feel free to speculate in the meantime.Boardman Elite SLR 9.2S
Boardman FS Pro0 -
From experience I know that single lense goggles are rubbish when it is properly cold.You only need two tools: WD40 and Duck Tape.
If it doesn't move and should, use the WD40.
If it shouldn't move and does, use the tape.0 -
But did they have anti fog coatings on both, or vents?0
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Daz555 wrote:From experience I know that single lense goggles are rubbish when it is properly cold.
And yet my experiance says otherwise.
Who'd have thought it hey?
For the record the only fogging I've encountered outside is when I stupidly put my goggles on my head in a gondaler (sp?) while the snow melts slightly on my hat. Cue instant blindness and random hate when going for the next slope.....
Of course they almost always fog up when going inside, but that's ok, they tend to clear after a beer!
For the record, Speedo swimming goggle anti fog works brilliantly even in the stupidity of putting goggle onto wet hat scenario.0
