View Poll Results: How do you clear your drive of snow?
Pay someone else to shovel, plow or snowblow
6
17.14%
Clear it yourself (plow, snowblower, etc.)
9
25.71%
Shovel it yourself
15
42.86%
Other
5
14.29%
Voters: 35. You may not vote on this poll
Merged Dealing with snow - plow, blower or shovel? & how do you clear your driveway
Sep 12th 2013, 7:08 pm
#61
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,439
Re: Snow country USA--how do you clear your driveway in the winter?
Although the bulk of the ice will stay in the solid form at any given moment, the surface will sublime slowly as long as the quantity of airborne moisture in contact with the ice stays below the vapor pressure. This gets accelerated greatly with wind, which takes the airborne moisture away to keep the system out of equilibrium.
Last edited by Pulaski; Sep 12th 2013 at 7:11 pm.
Sep 12th 2013, 8:29 pm
#62
BE Site Lead
Joined: Aug 2004
Location: MA, USA
Posts: 92,170
Re: Snow country USA--how do you clear your driveway in the winter?
Yeah, it's the ice storms that are the bigger threat round here too, though there hasn't been a major one since the winter of 2002-2003, thankfully. There was a very destructive one in December 2002, but that was just before I moved here. A few weeks later in early 2003 I went out to my car (I was still living in a hotel at the time), and it looked like my car had been frozen inside a giant ice cube. There was a solid, and eerily clear ½" layer of ice covering the whole car. Even the doors wouldn't pop open with the remote. 
In the following ten years it has never been that bad.
In the following ten years it has never been that bad.
Haven't gone through as much screen wash in the car down here compared to when we lived in Maine though, which is nice...because even at a couple bucks, the costs add up when you're chucking a tub in the car every week. Down here, can probably get away with maybe a couple refills a winter.
Sep 12th 2013, 8:56 pm
#63
I have a comma problem
Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Snow country USA--how do you clear your driveway in the winter?
Thermodynamics. F*** yeah 
Sep 12th 2013, 9:17 pm
#64
I have a comma problem
Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Snow country USA--how do you clear your driveway in the winter?
I know that, and didn't say it would. I said it would have to for sublimation to take place. At extremely low pressure the water molecules can be almost sucked off the surface of the ice, but otherwise the ice always has to melt before the molecules can break free and become a gas.
What you are describing is the surface of the ice melting and evaporating, which is completely different from the phenomenon of a sublimation, a solid substance turning directly into its gaseous phase.
What you are describing is the surface of the ice melting and evaporating, which is completely different from the phenomenon of a sublimation, a solid substance turning directly into its gaseous phase.
Above 0C, it is melting and evaporating, as you describe.
But I'm a physicist, not a chemist, so don't quote me.
Byeeeee
Sep 12th 2013, 9:33 pm
#65
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,439
Re: Snow country USA--how do you clear your driveway in the winter?
Sep 12th 2013, 10:07 pm
#66
I have a comma problem
Joined: Feb 2009
Location: Fox Lake, IL (from Carrickfergus NI)
Posts: 49,598
Re: Snow country USA--how do you clear your driveway in the winter?
As is mine. I'm sure it's somewhere in between.
Sep 12th 2013, 10:24 pm
#67
The worse half of Weeze
Joined: Mar 2012
Location: Back in TX
Posts: 3,231
Re: Snow country USA--how do you clear your driveway in the winter?
http://www.chemguide.co.uk/physical/...diags.html#top
Sorry, my thermodynamics books are at work. But this says for fresh water (which ice is) that it has to pass through a liquid stage at 1 atm.
Sorry, my thermodynamics books are at work. But this says for fresh water (which ice is) that it has to pass through a liquid stage at 1 atm.
Sep 12th 2013, 11:32 pm
#68
Joined: Dec 2001
Location: Dixie, ex UK
Posts: 52,439
Re: Snow country USA--how do you clear your driveway in the winter?
http://www.chemguide.co.uk/physical/...diags.html#top
Sorry, my thermodynamics books are at work. But this says for fresh water (which ice is) that it has to pass through a liquid stage at 1 atm.
Sorry, my thermodynamics books are at work. But this says for fresh water (which ice is) that it has to pass through a liquid stage at 1 atm.
Last edited by Pulaski; Sep 13th 2013 at 12:00 am.
Sep 13th 2013, 1:59 am
#69
Powder Maggot
Joined: Nov 2004
Location: Nuevo Mexico
Posts: 4,452
Re: Snow country USA--how do you clear your driveway in the winter?
The key is know that you are not dealing with an equilibrium state.
The phase diagram says that the water will stay solid, but that only applies to the bulk material. At the surface, the ice *may* be in a non-equilibrium condition. For example, if the partial pressure of water is less than the vapor pressure of ice in the air contacting the surface, ice will sublime until the equilibrium condition is reached. If the air is then blown away and replaced with drier air, sublimation will occur again. This is one of the mechanisms used by frost-free freezers. It is also why your ice cubes shrink over time in the freeze, but it takes a lot of time without a direct energy input - nobody worries about their ice cubes disappearing in a few days. Snow sublimation is driven faster because of the sun's energy.
Use of the google:
http://examples.yourdictionary.com/e...ter-vapor.html
http://ga.water.usgs.gov/edu/watercyclesublimation.html
http://wxguys.ssec.wisc.edu/2011/02/...now-evaporate/
The phase diagram says that the water will stay solid, but that only applies to the bulk material. At the surface, the ice *may* be in a non-equilibrium condition. For example, if the partial pressure of water is less than the vapor pressure of ice in the air contacting the surface, ice will sublime until the equilibrium condition is reached. If the air is then blown away and replaced with drier air, sublimation will occur again. This is one of the mechanisms used by frost-free freezers. It is also why your ice cubes shrink over time in the freeze, but it takes a lot of time without a direct energy input - nobody worries about their ice cubes disappearing in a few days. Snow sublimation is driven faster because of the sun's energy.
Use of the google:
http://examples.yourdictionary.com/e...ter-vapor.html
http://ga.water.usgs.gov/edu/watercyclesublimation.html
http://wxguys.ssec.wisc.edu/2011/02/...now-evaporate/
Sep 13th 2013, 2:04 am
#70
The worse half of Weeze
Joined: Mar 2012
Location: Back in TX
Posts: 3,231
Re: Snow country USA--how do you clear your driveway in the winter?
The key is know that you are not dealing with an equilibrium state.
The phase diagram says that the water will stay solid, but that only applies to the bulk material. At the surface, the ice *may* be in a non-equilibrium condition. For example, if the partial pressure of water is less than the vapor pressure of ice in the air contacting the surface, ice will sublime until the equilibrium condition is reached. If the air is then blown away and replaced with drier air, sublimation will occur again. This is one of the mechanisms used by frost-free freezers. It is also why your ice cubes shrink over time in the freeze, but it takes a lot of time without a direct energy input - nobody worries about their ice cubes disappearing in a few days. Snow sublimation is driven faster because of the sun's energy.
Use of the google:
http://examples.yourdictionary.com/e...ter-vapor.html
http://ga.water.usgs.gov/edu/watercyclesublimation.html
http://wxguys.ssec.wisc.edu/2011/02/...now-evaporate/
The phase diagram says that the water will stay solid, but that only applies to the bulk material. At the surface, the ice *may* be in a non-equilibrium condition. For example, if the partial pressure of water is less than the vapor pressure of ice in the air contacting the surface, ice will sublime until the equilibrium condition is reached. If the air is then blown away and replaced with drier air, sublimation will occur again. This is one of the mechanisms used by frost-free freezers. It is also why your ice cubes shrink over time in the freeze, but it takes a lot of time without a direct energy input - nobody worries about their ice cubes disappearing in a few days. Snow sublimation is driven faster because of the sun's energy.
Use of the google:
http://examples.yourdictionary.com/e...ter-vapor.html
http://ga.water.usgs.gov/edu/watercyclesublimation.html
http://wxguys.ssec.wisc.edu/2011/02/...now-evaporate/
Sep 13th 2013, 2:20 am
#71
.
Joined: Nov 2002
Location: Where bad things rarely happen in movies
Posts: 8,933
Re: Snow country USA--how do you clear your driveway in the winter?
The problem isn't that you've had too much wine to think about it properly, but that you've had too little to forget about it totally!
Sep 13th 2013, 2:21 am
#72
The worse half of Weeze
Joined: Mar 2012
Location: Back in TX
Posts: 3,231
Sep 13th 2013, 1:29 pm
#73
gurt mint nit?
Joined: Nov 2007
Location: In my shed
Posts: 2,776
Re: Snow country USA--how do you clear your driveway in the winter?
Actually I do have to chime in briefly - water ice will sublime, albeit slowly, at temperatures below 0C if energy (in the form of sunlight) is added.
Above 0C, it is melting and evaporating, as you describe.
But I'm a physicist, not a chemist, so don't quote me.
Byeeeee
Above 0C, it is melting and evaporating, as you describe.
But I'm a physicist, not a chemist, so don't quote me.
Byeeeee
Sep 13th 2013, 1:54 pm
#75
Under blue skies
Thread Starter
Joined: Mar 2011
Location: East Anglia->New England
Posts: 3,624