Support the Arctic Sea Ice Forum and Blog

Poll

If you combine 1 kilogram of ice (0C) and 1 kilogram of water (80C) what is the final temperature?

2 kilograms of 40C water
2 kilograms of 60C water with some ice in it.
2 kilograms of water at 20C
2 kilograms of water at 0 C

Author Topic: Do you understand the Enthalpy of Fusion of ice?  (Read 2853 times)

Fairbanksnchill

  • New ice
  • Posts: 13
    • View Profile
  • Liked: 0
  • Likes Given: 0
Do you understand the Enthalpy of Fusion of ice?
« on: August 31, 2016, 10:15:29 PM »
If it was not for Paul Beckwith (University of Ottowa , department of paleoclimatology) I would not have known the answer.  I had to do the experiment myself to believe it. When you undestand the answer it changes how you see the arctic and the whole worlds climate.

TerryM

  • First-year ice
  • Posts: 6002
    • View Profile
  • Liked: 892
  • Likes Given: 5
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #1 on: August 31, 2016, 10:28:08 PM »
This I believe, is the reason that many express little fear of the effects of an ice free arctic. All of that energy, now being used to melt ice, will instead be heating the Arctic Ocean.
Not a happy train of thought.
Terry

DaveHitz

  • New ice
  • Posts: 30
    • View Profile
  • Liked: 9
  • Likes Given: 1
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #2 on: September 01, 2016, 07:59:23 AM »
Here is the physics. (From one whose last physics class was 32 years ago. Plus, I had a glass of sake. So beware.)

The definition of a calorie is the amount of energy to raise 1 gram of water 1 degree C.

To melt one gram of water takes 80 calories. (https://www.google.com/?ion=1&espv=2#q=calories%20to%20freeze%20on%20g%20of%20water).

So take 1g of ice combined with 1g of water at 80C, and you get 2g of water at 0C.

What does this mean for the arctic? The amount of energy required to melt 1g of ice will heat that same 1g of ice by 80C. Which is to say, melting ice absorbs an astounding amount of energy. What if the ice weren't there? Then instead of melting 1g of ice, you would heat that same 1g of water by 80 degrees! Or more realistically, you'd heat 10g by 8 degrees or 100g by 0.8 degrees.

Point being, things get really hot, really fast.

johnm33

  • Guest
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #3 on: September 01, 2016, 10:28:08 AM »
"Point being, things get really hot, really fast."
Good job evaporation is even more energy intensive then.

sidd

  • First-year ice
  • Posts: 5953
    • View Profile
  • Liked: 845
  • Likes Given: 0
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #4 on: September 01, 2016, 07:39:04 PM »
"Good job evaporation is even more energy intensive then."

Agreed that latent heat of evaporation is 540 cal/gm compared to 80 for fusion. But ...

At sufficiently high temperatures (as in some parts of the tropical ocean), a "super greenhouse" feedback is triggered thus. A fractional increase of temperature, causes a fractional increase in evaporation, increasing water vapour in the air over the ocean. Water vapor is a very potent greenhouse gas, so the back radiation increases, heating the water even more, raising the temperature, and increasing evaporation, greenhouse effect,  back radiation, und so weiter.

Voila! very deep moist tropical convection, as seen in TRMM and other views.

of course, this situation fixes itself as the heat is removed by deep convection to top of atmosphere ... give or take a typhoon or two ...

sidd

andy_t_roo

  • New ice
  • Posts: 61
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #5 on: September 01, 2016, 10:04:16 PM »

So take 1g of ice combined with 1g of water at 80C, and you get 2g of water at 0C.

What does this mean for the arctic? The amount of energy required to melt 1g of ice will heat that same 1g of ice by 80C. Which is to say, melting ice absorbs an astounding amount of energy. What if the ice weren't there? Then instead of melting 1g of ice, you would heat that same 1g of water by 80 degrees! Or more realistically, you'd heat 10g by 8 degrees or 100g by 0.8 degrees.

Point being, things get really hot, really fast.

Except that the volume of ice is quite low, what do you get when you mix a water column of 1m of ice (0c) and 80m of water (1c); the same all water 0c.

We have been discussing the effects of wave action on the ice elsewhere  and recent estimates of the storms have the swell penetrating  broken Ice and mixing the top 50+m. And we see this effect with large swathes of ice quickly melting under certain storms.

weatherdude88

  • Frazil ice
  • Posts: 154
    • View Profile
  • Liked: 6
  • Likes Given: 0
Re: Do you understand the Enthalpy of Fusion of ice?
« Reply #6 on: September 15, 2016, 07:42:08 PM »
Since we are discussing the Enthalpy of Fusion, it is only fair we also discuss the Mpemba effect. Warm/hot water under certain conditions freezes faster than colder water.