Support the Arctic Sea Ice Forum and Blog

Author Topic: "Stupid" Questions :o  (Read 538949 times)

Glen Koehler

  • Frazil ice
  • Posts: 113
    • View Profile
  • Liked: 108
  • Likes Given: 140
Re: "Stupid" Questions :o
« Reply #2050 on: June 25, 2019, 11:41:54 PM »
     Has anyone come up with a numerical relationship between Arctic sea ice compactness and average pack rotation speed, or amount of export out the Fram Strait? 

     I'm spooked by the idea that decades of  cumulative thinning and removal of old ice as anchors has led to a functionally new state in the CAB ice pack making it more vulnerable to wind or current driven transport. 

   During the GAC in 2012 there were comments that if the ice had been thicker the cyclone damage to the ice would have been much less, but the average thickness by then had been reduced enough to allow much more wave damage.  Since 2012 the trend towards thinner and more rotten ice has had another 7 years to make the remaining ice even more vulnerable today.  Any observations about average pack rotation 2019 vs. earlier years much appreciated. 

   Wipneus's Farm Strait export chart doesn't show increasing export trend, so my logic may be missing key factor.  And I don't know of any other measure of export loss or pack mobility.  It just seems to be rotating more this year.  If there was a correlation of mobility or transport with compactness that would at least provide a measure to track this issue and indicate I'm not making all this up in my head. 

gerontocrat

  • First-year ice
  • Posts: 6564
    • View Profile
  • Liked: 1516
  • Likes Given: 21
Re: "Stupid" Questions :o
« Reply #2051 on: June 26, 2019, 12:00:24 AM »
     
   Wipneus's Farm Strait export chart doesn't show increasing export trend, so my logic may be missing key factor.  And I don't know of any other measure of export loss or pack mobility.  It just seems to be rotating more this year.  If there was a correlation of mobility or transport with compactness that would at least provide a measure to track this issue and indicate I'm not making all this up in my head.
The increased mobility of the ice seems to me a feature of this year. Too many posts mentioning it about areas all over the Arctic not to be significant, and MYI down again.

Wipneus shows, I think, export volume. As the years go by the ice has thinned. All things being equal then export volume would reduce. If export volume is not going down, then larger areas are being cleared out of the Arctic.

Spooky, I should say so. All the arguments are about when, not if, summer sea ice tends to zero(ish).
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

bluice

  • Frazil ice
  • Posts: 131
    • View Profile
  • Liked: 37
  • Likes Given: 154
Re: "Stupid" Questions :o
« Reply #2052 on: June 26, 2019, 07:07:37 PM »
I humbly ask one of the experts or well learned regulars here to shortly explain what qualifies as the dreaded dipole over the Arctic and how does it work?
In PIOMAS we trust

kynde

  • New ice
  • Posts: 19
    • View Profile
  • Liked: 4
  • Likes Given: 44
Re: "Stupid" Questions :o
« Reply #2053 on: June 26, 2019, 09:33:35 PM »
I'm not an expert, but wikipedia has a decent page about it that you can read before one of the weather gurus chime in here and provides more insight.

https://en.wikipedia.org/wiki/Arctic_dipole_anomaly

thejazzmarauder

  • New ice
  • Posts: 13
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: "Stupid" Questions :o
« Reply #2054 on: June 26, 2019, 11:27:09 PM »
I humbly ask one of the experts or well learned regulars here to shortly explain what qualifies as the dreaded dipole over the Arctic and how does it work?
A normal dipole pulls in warm air from the pacific side across the CAB and sends more ice out to die via the fram. A negative dipole does the opposite.

nanning

  • Grease ice
  • Posts: 892
  • 0Kg CO2, 35 KWh/wk,130L H2O/wk, No heating
    • View Profile
  • Liked: 137
  • Likes Given: 5848
Re: "Stupid" Questions :o
« Reply #2055 on: June 28, 2019, 05:57:46 AM »
I've wondered about this for a while:
When I read "a drop of -1,000 km2", I get that statement as indicating an increase, not a decrease. Losing -1 is the same as gaining 1.
Am I thinking correct here?
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

b_lumenkraft

  • Guest
Re: "Stupid" Questions :o
« Reply #2056 on: June 28, 2019, 06:05:34 AM »
Yes!

oren

  • Young ice
  • Posts: 4467
    • View Profile
  • Liked: 866
  • Likes Given: 1286
Re: "Stupid" Questions :o
« Reply #2057 on: June 28, 2019, 02:35:08 PM »
No.

Tor Bejnar

  • Young ice
  • Posts: 3046
    • View Profile
  • Liked: 365
  • Likes Given: 188
Re: "Stupid" Questions :o
« Reply #2058 on: June 28, 2019, 03:32:12 PM »
Some things you must look at context to understand.
My bug-a-boo is "bimonthly".  Are we to receive six reports a year or twenty-four?  And there is a perfectly good term for twice-a-month: semimonthly, but that doesn't change what bimonthly can mean.  Sigh :-\
Arctic ice is healthy for children and other living things.

b_lumenkraft

  • Guest
Re: "Stupid" Questions :o
« Reply #2059 on: June 28, 2019, 03:51:55 PM »
If it was 6, wouldn't you say 'every other month'?

magnamentis

  • Guest
Re: "Stupid" Questions :o
« Reply #2060 on: June 28, 2019, 04:11:58 PM »
I've wondered about this for a while:
When I read "a drop of -1,000 km2", I get that statement as indicating an increase, not a decrease. Losing -1 is the same as gaining 1.
Am I thinking correct here?

the term "drop" is not a mathematical term hence if you say a round circle that would not make it anything else but a circle ;)

a drop of -1000 is nothing else then an a description followed by how much while the use of
a drop of 1000 would be my choice. lets call it an emphasizes or a copy paste thing or a
mental lapse in the middle of the sentence but not mathematically significant or wrong.

Tor Bejnar

  • Young ice
  • Posts: 3046
    • View Profile
  • Liked: 365
  • Likes Given: 188
Re: "Stupid" Questions :o
« Reply #2061 on: June 28, 2019, 05:56:34 PM »
If a report came out 6 x per year (in regular increments), I'd say it was bimonthly, but the smart money would say 'every other month' to be clear. [I'd rather be right than smart … :)]
If a report came out 24 x per year (in regular increments), I'd say it was semimonthly.
'Professional' discussion here.
Arctic ice is healthy for children and other living things.

nanning

  • Grease ice
  • Posts: 892
  • 0Kg CO2, 35 KWh/wk,130L H2O/wk, No heating
    • View Profile
  • Liked: 137
  • Likes Given: 5848
Re: "Stupid" Questions :o
« Reply #2062 on: June 28, 2019, 06:04:18 PM »
the term "drop" is not a mathematical term hence if you say a round circle that would not make it anything else but a circle ;)

a drop of -1000 is nothing else then an a description followed by how much while the use of
a drop of 1000 would be my choice. lets call it an emphasizes or a copy paste thing or a
mental lapse in the middle of the sentence but not mathematically significant or wrong.

But "Drop" is a physical term. Dropping means going down. Going lower.
Okay, it's an interpretation but backed up by reality.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

magnamentis

  • Guest
Re: "Stupid" Questions :o
« Reply #2063 on: June 28, 2019, 06:22:04 PM »
the term "drop" is not a mathematical term hence if you say a round circle that would not make it anything else but a circle ;)

a drop of -1000 is nothing else then an a description followed by how much while the use of
a drop of 1000 would be my choice. lets call it an emphasizes or a copy paste thing or a
mental lapse in the middle of the sentence but not mathematically significant or wrong.

But "Drop" is a physical term. Dropping means going down. Going lower.
Okay, it's an interpretation but backed up by reality.

drop means first of all falling and i agree with you that the understanding is clear but nevertheless it's also not a physical (in terms of physics) term. it's semantics but i think it's clear who means what.

i mostly agree with you as far as the sentence was not the way i or you would have written it and that there is some room for interpretation. nevertheless since the term "drop" is about common sense more than maths and physics (- - = +) it's not really relevant.

however i think it's all said and it's neither important nor is there significant disagreement worth a lengthy discussion IMO, othes feel free to continue, i'm out because i've nothing meaningful to add further ;) ;)

enjoy the weekend @all

nanning

  • Grease ice
  • Posts: 892
  • 0Kg CO2, 35 KWh/wk,130L H2O/wk, No heating
    • View Profile
  • Liked: 137
  • Likes Given: 5848
Re: "Stupid" Questions :o
« Reply #2064 on: June 28, 2019, 07:56:16 PM »
Thanks magnamentis, I agree, it's not important outside this little discussion. All is said. Enjoy your weekend too.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

be cause

  • Grease ice
  • Posts: 886
  • Citizenship .. a Lurker gets asylum
    • View Profile
  • Liked: 254
  • Likes Given: 217
Re: "Stupid" Questions :o
« Reply #2065 on: June 28, 2019, 10:18:01 PM »
 while on Worldview recently I casually centred on the pole .. I looked and noticed not only was I at 90'.00.00 N but also at 90'.00.00 West .. I wondered why . Since then I have found it impossible to perfectly centre on the pole again to see if longitude always appeared as 90' west .. can a steady hand confirm either way ? .. b.c.
2007 + 5 = 2012 + 4 = 2016 + 3 = 2019 ...

nanning

  • Grease ice
  • Posts: 892
  • 0Kg CO2, 35 KWh/wk,130L H2O/wk, No heating
    • View Profile
  • Liked: 137
  • Likes Given: 5848
Re: "Stupid" Questions :o
« Reply #2066 on: June 29, 2019, 04:57:34 AM »
Just a thought: 90°00' 00'' could be a rounding of 89°59' 59.9'' ? Perhaps you were not exactly at the pole.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

Sebastian Jones

  • Frazil ice
  • Posts: 314
    • View Profile
  • Liked: 52
  • Likes Given: 40
Re: "Stupid" Questions :o
« Reply #2067 on: July 01, 2019, 07:47:56 AM »

Long shot:
Over the years I've noticed that Pangnirtung fiord  melts out before Frobisher bay, its neighbour to the south.
Does anyone know why?
The Forum used to include a resident of Iqaluit, who seems to have gone dark in the past year, I bet they knew what the key difference is.

nanning

  • Grease ice
  • Posts: 892
  • 0Kg CO2, 35 KWh/wk,130L H2O/wk, No heating
    • View Profile
  • Liked: 137
  • Likes Given: 5848
Re: "Stupid" Questions :o
« Reply #2068 on: July 01, 2019, 10:42:30 AM »
@Sebastian Jones
I guess it could be a current of warmer water that makes a U-turn in the bay and comes up to 'surface' in the corner where the fjord is.
Does that make sense?
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
   Simple: minimize your possessions and be free and kind    It's just a mindset.       Refugees welcome

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2069 on: July 01, 2019, 12:03:07 PM »
Let's assume we have a glass of water which resembles the Arctic in makeup. The glass in the example is 8" tall. The water line is 4" high and comprised of fresh near freezing water in the upper half inch. The bottom 3.5 inches is warmer salty water.

Of course, being an Arctic example, there must also be ice in the glass and it rises up to 2" above the water line to the 6" mark of the glass.

If we add warmer fresh water (say 8C) to the glass, what happens? Let's say the amount is enough to fill in the volume up to the 6" line where the ice peak is.

Will the new water stratify on top of the existing fresh water layer or will the gravitational effect push existi g water under the ice causing the ice to float higher?

binntho

  • Nilas ice
  • Posts: 1048
    • View Profile
  • Liked: 275
  • Likes Given: 75
Re: "Stupid" Questions :o
« Reply #2070 on: July 01, 2019, 12:12:11 PM »
Of course, being an Arctic example, there must also be ice in the glass and it rises up to 2" above the water line to the 6" mark of the glass.
So the ice reaches 18" under the water line or 10" below the level of the table. Doesn't sound like much of an Arctic example to me.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

oren

  • Young ice
  • Posts: 4467
    • View Profile
  • Liked: 866
  • Likes Given: 1286
Re: "Stupid" Questions :o
« Reply #2071 on: July 01, 2019, 01:13:27 PM »
Let's assume we have a glass of water which resembles the Arctic in makeup. The glass in the example is 8" tall. The water line is 4" high and comprised of fresh near freezing water in the upper half inch. The bottom 3.5 inches is warmer salty water.

Of course, being an Arctic example, there must also be ice in the glass and it rises up to 2" above the water line to the 6" mark of the glass.

If we add warmer fresh water (say 8C) to the glass, what happens? Let's say the amount is enough to fill in the volume up to the 6" line where the ice peak is.

Will the new water stratify on top of the existing fresh water layer or will the gravitational effect push existi g water under the ice causing the ice to float higher?
This is the fourth thread in which you have asked the same question, and the answer is the same. Really basic physics. Ice floats on both fresh water and salty water, both cold water and warm water. Whatever happens to the water layers in your example, whether they mix or stratify and whichever layer gets on top, the ice will immediately rise and float on top of the whole water column.
(I ignore the fact the ice is 9/10 underwater, as this was neglected in your example).
Why not do the experiment at home? Take ice, cold and warm water, fresh and salty water. Try it in various combinations. Best to use colored water so that you can see the layers (if they form).

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2072 on: July 01, 2019, 02:58:42 PM »
Let's assume we have a glass of water which resembles the Arctic in makeup. The glass in the example is 8" tall. The water line is 4" high and comprised of fresh near freezing water in the upper half inch. The bottom 3.5 inches is warmer salty water.

Of course, being an Arctic example, there must also be ice in the glass and it rises up to 2" above the water line to the 6" mark of the glass.

If we add warmer fresh water (say 8C) to the glass, what happens? Let's say the amount is enough to fill in the volume up to the 6" line where the ice peak is.

Will the new water stratify on top of the existing fresh water layer or will the gravitational effect push existi g water under the ice causing the ice to float higher?
This is the fourth thread in which you have asked the same question, and the answer is the same. Really basic physics. Ice floats on both fresh water and salty water, both cold water and warm water. Whatever happens to the water layers in your example, whether they mix or stratify and whichever layer gets on top, the ice will immediately rise and float on top of the whole water column.
(I ignore the fact the ice is 9/10 underwater, as this was neglected in your example).
Why not do the experiment at home? Take ice, cold and warm water, fresh and salty water. Try it in various combinations. Best to use colored water so that you can see the layers (if they form).

You make a good point about the ice extending below the water line. I didn't neglect it, I assumed that it was obvious and didn't spell it out.

But now that you mention it, let's address that. Let's assume the ice is deep enough in the water that is floating on top of the deeper denser layer.

Adding lighter water to the glass doesn't change the water column that the ice is resting on. It's still going to be floating on the same dense layer if the new water doesn't mix.

In theory, you can add lighter water water all the way up to the 6" line which will not impact the relationship between the ice and the dense water underneath it.

The impetus for the ice to change location would be when the water level exceeds the height of the ice. Then the lesser density of the ice would cause it to move vertically.

To your point, I've raised the question and it hasn't been answered. Perhaps because my articulation hasn't been great, perhaps because the point I"m trying to make now is not the same one I started with. I'm not blaming anyone else, but I am persisting in trying to understand. I'm curious and I don't give up easily.

kassy

  • Grease ice
  • Posts: 764
    • View Profile
  • Liked: 279
  • Likes Given: 331
Re: "Stupid" Questions :o
« Reply #2073 on: July 01, 2019, 03:37:11 PM »
Let's assume the ice is deep enough in the water that is floating on top of the deeper denser layer.

In the real world the fresh water layer is always much bigger because it is a product of ice melt and river water inflow.

The impetus for the ice to change location would be when the water level exceeds the height of the ice.

Make icecubes and drown them.
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

binntho

  • Nilas ice
  • Posts: 1048
    • View Profile
  • Liked: 275
  • Likes Given: 75
Re: "Stupid" Questions :o
« Reply #2074 on: July 01, 2019, 03:42:01 PM »
I assume that most people know that ice floats in water, and that the density relationship is 1/10 or therabouts, i.e. 1/10th of the mass of a floting bit of ice will stick out of the water.

So an ice floe that is 1m thick will have a freeboard of 10cm and a 2m thick floe will have a freeboard of 20 cm. The sea ice in the Chukchi is definitely not thicker than 2 m!

The density of water is defined as 1 for pure water at 4 degrees Centigrades. Another way of expressing this is in kg/m3, so clean water at 4 degrees has a density of 1000 kg/m3

Water density will increase with added salt, the oceans have a typical density of 1020 - 1030 kg/m3 due to their salt content.

Water density will decrease with increased temperature, water at 1atm and 99C (i.e. just short of boiling) has a density of 960 kg/m3.

Ice has a density of 916 kg/m3 at 0 degrees and gets heavier as the temperature falls, is 921 kg/m3 at -50 degrees Centigrade, and 926 kg/m3 at -100.

What all this means is that ice wil allways float in water - even if you were to take the heaviest ice you could reasonably find (cooled with liquid nitrogen say) and plunge it into almost boiling water, it would still float.

So there is really no realistic real world scenario where water will float on ice due to density variations.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2075 on: July 01, 2019, 03:56:34 PM »
Let's assume the ice is deep enough in the water that is floating on top of the deeper denser layer.

In the real world the fresh water layer is always much bigger because it is a product of ice melt and river water inflow.

The impetus for the ice to change location would be when the water level exceeds the height of the ice.

Make icecubes and drown them.

Yes, the water level in the real world is bigger than the level in my imaginary water glass. Thank you Captain Obvious !!!

I'm trying to construct an example which minimizes the variables and demonstrate that it is possible to add water to an environment where ice is floating without causing the ice to rise.

Oren makes some a valuable reference to the water column. The column is stratified vertically according to relative density.

If ice is floating in a glass of only salt water and we add fresh water to the glass, the fresh water is not going to mix and change the existing vertical relationship between the ice and salt water. The newly added fresh water will exist in a separate column atop the salt water adjacent to the column that the ice is in.

crandles

  • Young ice
  • Posts: 2511
    • View Profile
  • Liked: 94
  • Likes Given: 47
Re: "Stupid" Questions :o
« Reply #2076 on: July 01, 2019, 03:57:44 PM »
Under enough pressure different types of ice form and some these can be denser than water. However the pressures are extremely high and none of these ices are found naturally on the surface of Earth so I agree with "no realistic real world scenario".

https://physics.stackexchange.com/questions/265666/is-there-a-temperature-at-which-ice-is-denser-than-water

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2077 on: July 01, 2019, 04:01:52 PM »
I assume that most people know that ice floats in water, and that the density relationship is 1/10 or therabouts, i.e. 1/10th of the mass of a floting bit of ice will stick out of the water.

So an ice floe that is 1m thick will have a freeboard of 10cm and a 2m thick floe will have a freeboard of 20 cm. The sea ice in the Chukchi is definitely not thicker than 2 m!

The density of water is defined as 1 for pure water at 4 degrees Centigrades. Another way of expressing this is in kg/m3, so clean water at 4 degrees has a density of 1000 kg/m3

Water density will increase with added salt, the oceans have a typical density of 1020 - 1030 kg/m3 due to their salt content.

Water density will decrease with increased temperature, water at 1atm and 99C (i.e. just short of boiling) has a density of 960 kg/m3.

Ice has a density of 916 kg/m3 at 0 degrees and gets heavier as the temperature falls, is 921 kg/m3 at -50 degrees Centigrade, and 926 kg/m3 at -100.

What all this means is that ice wil allways float in water - even if you were to take the heaviest ice you could reasonably find (cooled with liquid nitrogen say) and plunge it into almost boiling water, it would still float.

So there is really no realistic real world scenario where water will float on ice due to density variations.

That's a good explanation and answer to a question that hasn't been asked. No one is suggesting an environment where ice ceases to float on water.

Read the question carefully.

kassy

  • Grease ice
  • Posts: 764
    • View Profile
  • Liked: 279
  • Likes Given: 331
Re: "Stupid" Questions :o
« Reply #2078 on: July 01, 2019, 04:10:22 PM »
So basically you are having a really bad trip about imaginary processes drowning the ice while it remains floating and require us to come up with something sensible about that.

You can read about the arctic fresh water lense in science.

demonstrate that it is possible to add water to an environment where ice is floating without causing the ice to rise.

We call that rain.
Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

BenB

  • Frazil ice
  • Posts: 282
    • View Profile
  • Liked: 50
  • Likes Given: 13
Re: "Stupid" Questions :o
« Reply #2079 on: July 01, 2019, 04:13:23 PM »
Adding lighter water to the glass doesn't change the water column that the ice is resting on. It's still going to be floating on the same dense layer if the new water doesn't mix.

In theory, you can add lighter water water all the way up to the 6" line which will not impact the relationship between the ice and the dense water underneath it.

If I understand what you're saying correctly, I think you're misunderstanding how hydrostatic pressure works. The water column doesn't need to be directly above you for it to affect the water pressure at a point below the surface.

I'll give two different kinds of (brief) explanation:
  • Imagine a diver swims down to 10 metres below sea level. He then swims horizontally into a cave where there is only 1 metre of water above him. The water pressure will be the same in the cave as it was outside it.
  • In your glass of water, the water pressure directly below the water you've added will increase, because there will be a higher water column above it. Water pressure acts in all directions. The pressure under the water you've added can't remain higher than in the water next to it under the ice cube, because it would displace that water, as it would be pushing "harder" than the other water would be pushing back. So, in fact it reaches a new equilibrium where the pressure is the same everywhere at the same depth.

Is that what you meant? And does that help?
« Last Edit: July 01, 2019, 04:50:41 PM by BenB »

gerontocrat

  • First-year ice
  • Posts: 6564
    • View Profile
  • Liked: 1516
  • Likes Given: 21
Re: "Stupid" Questions :o
« Reply #2080 on: July 01, 2019, 04:22:00 PM »
Under enough pressure different types of ice form and some these can be denser than water. However the pressures are extremely high and none of these ices are found naturally on the surface of Earth so I agree with "no realistic real world scenario".
Amend "no realistic real world scenario" to "no realistic scenario on earth except in the laboratory"

It seems the earth's hexagonal ice is not found in the interstellar medium (i.e. in space). This stuff is...

Really interesting but not relevant to Arctic Sea Ice. Ice floats. End of.

Quote
Low-density amorphous ice
Low-density amorphous ice, also called LDA, vapor-deposited amorphous water ice, amorphous solid water (ASW) or hyperquenched glassy water (HGW), is usually formed in the laboratory by a slow accumulation of water vapor molecules (physical vapor deposition) onto a very smooth metal crystal surface under 120 K. In outer space it is expected to be formed in a similar manner on a variety of cold substrates, such as dust particles.[2]

Melting past its glass transition temperature (Tg) between 120 and 140 K, LDA is more viscous than normal water. Recent studies have shown the viscous liquid stays in this alternative form of liquid water up to somewhere between 140 and 210 K, a temperature range that is also inhabited by ice Ic.[3][4][5] LDA has a density of 0.94 g/cm3, less dense than the densest water (1.00 g/cm3 at 277 K), but denser than ordinary ice (ice Ih).

Hyperquenched glassy water (HGW) is formed by spraying a fine mist of water droplets into a liquid such as propane around 80 K or by hyperquenching fine micrometer-sized droplets on a sample-holder kept at liquid nitrogen temperature, 77 K, in a vacuum. Cooling rates above 104 K/s are required to prevent crystallization of the droplets. At liquid nitrogen temperature, 77 K, HGW is kinetically stable and can be stored for many years.

High-density amorphous ice
High-density amorphous ice (HDA) can be formed by compressing ice Ih at temperatures below ~140 K. At 77 K, HDA forms from ordinary natural ice at around 1.6 GPa[6] and from LDA at around 0.5 GPa[7] (approximately 5,000 atm). At this temperature, it can be recovered back to ambient pressure and kept indefinitely. At these conditions (ambient pressure and 77 K), HDA has a density of 1.17 g/cm3.[6]

Peter Jenniskens and David F. Blake demonstrated in 1994 that a form of high-density amorphous ice is also created during vapor deposition of water on low-temperature (< 30 K) surfaces such as interstellar grains. The water molecules do not fully align to create the open cage structure of low-density amorphous ice. Many water molecules end up at interstitial positions. When warmed above 30 K, the structure re-aligns and transforms into the low-density form.[3][8]

Very-high-density amorphous ice
Very-high-density amorphous ice (VHDA) was discovered in 1996 by Osamu Mishima who observed that HDA became denser if warmed to 160 K at pressures between 1 and 2 GPa and has a density of 1.26 g/cm3 at ambient pressure and temperature of 77 K.[9] More recently it was suggested that this denser amorphous ice was a third amorphous form of water, distinct from HDA, and was named VHDA.[10]
https://en.wikipedia.org/wiki/Amorphous_ice
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

Grubbegrabben

  • New ice
  • Posts: 31
    • View Profile
  • Liked: 8
  • Likes Given: 11
Re: "Stupid" Questions :o
« Reply #2081 on: July 01, 2019, 04:35:47 PM »
If water (A) is added in cracks between ice floes it will displace the water below (C).
It will not magically float on top (B).
Even if it doesnt mix.

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2082 on: July 01, 2019, 04:50:57 PM »
I'm going to start over with even fewer variables.

We start with the same glass, but it contains only very cold salt water (density > 1 g / ml) and a single sphere of fresh water ice (density of .916 g / ml according to above post which I'll accept at face value)

The diameter of the glass opening is 4" and the diameter of the ice sphere is 2", something less than the full diameter of the glass.

If we add something denser than the salt water (like a rock) it sinks to the bottom and all of the water and ice moves up in tandem.

If we add something lighter than the ice (like feathers) we can pile them up on top without causing a change in the height of the water and ice.

What happens if we carefully add a substance whose density is less than the salt water, but greater than the density of the ice? Something like fresh room temperature water?

If we add it carefully so as not to disturb the column of water in the glass, the newly added water will not mix  with the colder dense water at the bottom of the glass. It will form a new layer on top of it.

Note that there is no suggestion that the ice will ever stop floating. It will continue to float on the densest water in the column beneath it.

The weight of the new water layer on top may cause a slight pressure change, but not mixing. We can add fresh water slowly to the perimeter of the glass and the amount of ice sticking out above the surface should decline.

In effect, you have two separate columns of water in one container. You have the column which is directly beneath the 2" sphere of ice and the remaining column beneath the newly added water.

The ice should begin to melt faster because the upper portion of it will now be immersed in the newly added warmer water.

Grubbegrabben

  • New ice
  • Posts: 31
    • View Profile
  • Liked: 8
  • Likes Given: 11
Re: "Stupid" Questions :o
« Reply #2083 on: July 01, 2019, 04:58:16 PM »
The ice will float on both types of water. It will not be immersed. Although the freeboard might be slightly less.

b_lumenkraft

  • Guest
Re: "Stupid" Questions :o
« Reply #2084 on: July 01, 2019, 05:01:05 PM »
If water (A) is added in cracks between ice floes it will displace the water below (C).
It will not magically float on top (B).
Even if it doesnt mix.

Hahahaha, what a great picture. Have you made it yourself?

binntho

  • Nilas ice
  • Posts: 1048
    • View Profile
  • Liked: 275
  • Likes Given: 75
Re: "Stupid" Questions :o
« Reply #2085 on: July 01, 2019, 05:06:15 PM »
Well a rather decently described experiment that you could easily replicate in your kitchen.

I'm going to start over with even fewer variables.

We start with the same glass, but it contains only very cold salt water (density > 1 g / ml) and a single sphere of fresh water ice (density of .916 g / ml according to above post which I'll accept at face value)

The diameter of the glass opening is 4" and the diameter of the ice sphere is 2", something less than the full diameter of the glass.

If we add something denser than the salt water (like a rock) it sinks to the bottom and all of the water and ice moves up in tandem.

If we add something lighter than the ice (like feathers) we can pile them up on top without causing a change in the height of the water and ice.

What happens if we carefully add a substance whose density is less than the salt water, but greater than the density of the ice? Something like fresh room temperature water?


At this point the fresh water will form a layer on top of the salt water, and lift the ice at the same time.  As you yourself explained regarding hydrostatic pressure, the pressure is the same at the same depth. When you raise the surface by adding water, the bottom of the ice will find itself at a greater depth and therefore at a greater pressure than before, causing it to instantly float upwards.


If we add it carefully so as not to disturb the column of water in the glass, the newly added water will not mix  with the colder dense water at the bottom of the glass. It will form a new layer on top of it.

Note that there is no suggestion that the ice will ever stop floating. It will continue to float on the densest water in the column beneath it.


No. The ice is floating in the water in the glass. The fresh water is considerably heavier than the ice and will push it up immediately, seeking to get under it.


The weight of the new water layer on top may cause a slight pressure change, but not mixing. We can add fresh water slowly to the perimeter of the glass and the amount of ice sticking out above the surface should decline.


No. The ice floats up with the water. Since the fresh water has a lower density than the water already in the glass, the total effect will be a slight reduction in the freeboard (i.e. the average density of the water has gone up, but the density of the ice has not changed).


In effect, you have two separate columns of water in one container. You have the column which is directly beneath the 2" sphere of ice and the remaining column beneath the newly added water.

No you do not. The ice does not maintain its own "water column" - since it is floating in a floating medium (!) the pressure evens out in all directions, and it makes absolutely no difference if the water is striped or layered.
because a thing is eloquently expressed it should not be taken to be as necessarily true
St. Augustine, Confessions V, 6

BenB

  • Frazil ice
  • Posts: 282
    • View Profile
  • Liked: 50
  • Likes Given: 13
Re: "Stupid" Questions :o
« Reply #2086 on: July 01, 2019, 05:14:10 PM »
Rich, pressure in a fluid acts in all directions (down, horizontally and, yes, upwards). You cannot have two separate columns that are in contact with one another. From the point of view of pressure and buoyancy, they are the same column. As I've already said, when you add more water to the top of the glass, you increase the pressure in the water at the bottom of the glass. Whatever the density of the new water.

A floating object displaces its own weight of water. In your example, the amount of water displaced by the ice cube would change when you add more water. This would imply that the ice cube had become heavier. This is clearly not the case. The only slight difference is as Binntho says, that the average density of the water has change. However, this would only mean that for each 1 cm of water you added, the ice cube would rise say 0.98 cm instead of 1 cm.

You should look up the buoyant force, hydrostatic pressure, communicating vases, Pascal's Principle and Archimedes' Principle.

crandles

  • Young ice
  • Posts: 2511
    • View Profile
  • Liked: 94
  • Likes Given: 47
Re: "Stupid" Questions :o
« Reply #2087 on: July 01, 2019, 05:21:01 PM »
What is difficult about this?

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2088 on: July 01, 2019, 05:24:58 PM »
Well, for what it's worth, I feel like the answer is now matching the question and I've learned something that I didn't understand when this saga began.

You've insulted me along the way Binntho but in the end delivered the explanation that makes sense to me as well. All in all, that's a good deal for me.

I don't give a hoot about being called names or being ignorant about certain things that most other people grasp. I did what I needed to do to learn something.

Thanks for your participation in this educational process.

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2089 on: July 01, 2019, 05:52:25 PM »
So, a little post mortem on the learning process here and question about best practices.

When I began this process yesterday, I'll be happy to acknowledge that I didn't understand the concept of hydrostatic pressure that has now been explained to me. (No secret to any of you)

Not being aware that was the understanding that eluded me, I couldn't very well be expected to have googled "hydrostatic pressure" if I wasn't aware of it.

So I began an iterative process and ended up constructing the example which isolated the variables and helped you spell it out for me.

Socially speaking, it wasn't an elegant process but it ended up getting the job done educationally.

If someone has a suggestion for a better approach in the future, I'll be happy to hear it. I don't have any hard feelings toward the people who insulted me along the way. I'm a good sport in the end. A pain in the ass as well, but coming from a genuine place.


b_lumenkraft

  • Guest
Re: "Stupid" Questions :o
« Reply #2090 on: July 01, 2019, 06:00:57 PM »
Assume less, ask more. That's what i can say. :)

PS: I too learned a lot about waves. Thanks, everyone who contributed!

oren

  • Young ice
  • Posts: 4467
    • View Profile
  • Liked: 866
  • Likes Given: 1286
Re: "Stupid" Questions :o
« Reply #2091 on: July 01, 2019, 06:36:49 PM »
Ask questions in the Questions thread, and avoid back and forth in the main threads. Once you moved to the proper thread the discussion was fruitful and did not disrupt.

Neven

  • Administrator
  • First-year ice
  • *****
  • Posts: 7174
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 713
  • Likes Given: 467
Re: "Stupid" Questions :o
« Reply #2092 on: July 01, 2019, 06:39:36 PM »
Ask questions in the Questions thread, and avoid back and forth in the main threads. Once you moved to the proper thread the discussion was fruitful and did not disrupt.

And you need to stop evaluating/meta-discussing/whining. It is getting annoying, and thus causes me extra work.
Il faut comparer, comparer, comparer, et cultiver notre jardin

Rich

  • Guest
Re: "Stupid" Questions :o
« Reply #2093 on: July 01, 2019, 08:51:39 PM »
Thanks everyone for the feedback.

I think it's easy in the future to come to the Stupid Questions thread more quickly. If I had done that in this case, the experience of others would not have been so unpleasant.

I apologize.

While I may be a pain in the ass at times, you can at least count on my contribution as being genuine as is my apology here.

RealityCheck

  • Frazil ice
  • Posts: 132
    • View Profile
  • Liked: 27
  • Likes Given: 5
Re: "Stupid" Questions :o
« Reply #2094 on: July 01, 2019, 10:06:32 PM »
Hey All
Re waves, ice and such: if I may offer a real-world analogy... floating breakwaters. There's youtube videos out there, I bet. I will search for links when not working from a phone. They are larger versions of pontoon marinas, and they have some similar characteristics to ice in the path of oncoming waves.
This is a bit simplified I know, but there are enough similarities to make it relevant,  I think.
Waves have a period, a height and a length. Floating breakwaters dispel energy for short waves at low periods, but not above 5 seconds. Low period waves splash off the pontoon face, onto or over the deck. Higher period (longer) waves cause pontoons to gently rise and fall, with minimal energy dissipation. Short fetch = short length / low period. Long fetch and long, strong winds = long wavelength & higher period waves. Within a marina basin, if waves are short, water is calm. Long waves = boats tossed about. But in neither case does water transmit past the pontoon to any meaningful degree. Wave height only determines amount of splash or tossing, depending on period...
Hope this is helpful.
Sic transit gloria mundi

Neven

  • Administrator
  • First-year ice
  • *****
  • Posts: 7174
    • View Profile
    • Arctic Sea Ice Blog
  • Liked: 713
  • Likes Given: 467
Re: "Stupid" Questions :o
« Reply #2095 on: July 01, 2019, 11:45:30 PM »
http://www.iup.uni-bremen.de:8084/amsr2/Arctic_AMSR2_nic.png

Amateur question, does this really point to the arctic breaking in two? It looks like there are two different area's with 100% ice.
Il faut comparer, comparer, comparer, et cultiver notre jardin

Sterks

  • Guest
Re: "Stupid" Questions :o
« Reply #2096 on: July 02, 2019, 01:03:35 AM »
I’ve seen worse (see maps of 2016 end of July or so).
But no, the pack is not a solid rigid, it can withstand these fractured extents or melting ice within, it’s basically all floating over the sea and more or less staying around the Pole (unless too much heat melts all out one year)

Sebastian Jones

  • Frazil ice
  • Posts: 314
    • View Profile
  • Liked: 52
  • Likes Given: 40
Re: "Stupid" Questions :o
« Reply #2097 on: July 02, 2019, 03:18:43 AM »
Thanks @Nanning, your hypothesis could be valid. I'm not aware of any warm current that  enters Pang fiord. There could be a sub-sea hot spring too, but without evidence, it is a thin explanation.
I'm assuming it is a feature of bathymetry.

wdmn

  • Frazil ice
  • Posts: 349
    • View Profile
  • Liked: 62
  • Likes Given: 48
Re: "Stupid" Questions :o
« Reply #2098 on: July 02, 2019, 05:30:07 AM »
Is there any reason that arctic sea ice loss should be linear?

I would expect it not to be given that there are feedbacks within the system (i.e. loss of albedo), but I'm wondering if there are arguments for why it should behave linearly?

Thanks


petm

  • Grease ice
  • Posts: 675
    • View Profile
  • Liked: 334
  • Likes Given: 27
Re: "Stupid" Questions :o
« Reply #2099 on: July 02, 2019, 05:50:33 AM »
@wdmn
There's this, for one:
https://forum.arctic-sea-ice.net/index.php/topic,933

Not really an argument for linearity, per se, but that positive feedbacks like decreased summer albedo might be cancelled out by negative feedbacks like increased winter ice growth.