Censorship so far today :
My post below is gone from Romm’s site. I wonder what he didn’t like? A clear violation of the TOU – LOL
Your comment is awaiting moderation.
Excellent news. Looks like my SEARCH forecast will probably win this year.
http://www.arcus.org/ search/ seaiceoutlook/ 2010/ august
http://www.ijis.iarc.uaf.edu/ seaice/ extent/ AMSRE_Sea_Ice_Extent.png
I’ve started my own blog. Most of you would probably appreciate this post.
I’d appreciate comments.
http://realclimatescience.com/ 2010/ 09/ 01/ over-in-america-we-have-this-rule-if-you-want-to-motivate-someone-dont-mention-death/
WUWT – jeez didn’t like me pointing out that the Arctic has all three phases of water at the same time, because his understanding of the phase diagram tells him that it can’t happen. So I got banned permanently. How dare me have a different opinion.
jeez says:
September 1, 2010 at 4:04 pm
Steven, this is your last thread on WUWT. You are going out on the most embarrassing note I could imagine. I could not have conceived of a script where you could behave worse.
Will Tamino do better? I’m betting he will. The verdict is still out.
stevengoddard | September 2, 2010 at 2:47 am | Reply
Your comment is awaiting moderation.
All – I’ve started my own blog. Here is an article you might enjoy.
Looking forward to hearing from you.
stevengoddard | September 2, 2010 at 3:20 am | Reply
Your comment is awaiting moderation.
Phil.
As I am sure you are aware, Anthony shut down comments – so it would be pretty difficult for me to respond.
However, it does appear that the 1999 “global graph” probably excluded the 70% of the globe which comprises the oceans, so the basis of my article was most likely incorrect.
———————————————————————
Updates for September 2.
Tamino fails on the first post, but posts the second.
Anthony informs that I have not been banned, rather the thread was cut off right after jeez’ last diatribe.
Your comment is awaiting moderation.
All – I’ve started my own blog. Here is an article you might enjoy.
http://realclimatescience.com/2010/09/01/over-in-america-we-have-this-rule-if-you-want-to-motivate-someone-dont-mention-death/
Looking forward to hearing from you.
stevengoddard | September 2, 2010 at 3:20 am | Reply
Your comment is awaiting moderation.
Phil.
As I am sure you are aware, Anthony shut down comments – so it would be pretty difficult for me to respond.
However, it does appear that the 1999 “global graph” probably excluded the 70% of the globe which comprises the oceans, so the basis of my article was most likely incorrect.
I have posted this in the reopenned sea ice comments page, I don’t know if it will be left or deleted as being “off topic”!
I think it was sad that the comments were closed for this sea ice report (and reopenned here) and Steve Goddard was lambasted so much by saying that waters tripple point can exist in the artic. Especially what Anthonys last post confirmes it by writing:
“liquid water, solid ice, and water vapour can coexist in a stable equilibrium occurs at exactly 273.16 K (0.01 °C) and a partial vapour pressure of 611.73 pascals.” [emphasis mine]
The important part is that it says “partial pressure” NOT total pressure!
In the artic you can get a temp of 0.01C and have a partial pressure of water of 611.73 pascals, so therefore Steve was right as each phase can exist in equiliblruim.
Jeez’s example of the impossibility a boiling glass of iced water is wrong as he has taken the definition of partial pressure to mean absolute pressure (boiling is simply vigorous evaporation). A glass containing iced water at 0.01C in an atmosphere were the PP of water is 611.73 pascals will infact containg all three states in equiliblruim with ice equally melting /freezing, water vapour subliming/condensing and liqued water freezing/melting and evaporating/condensing.
What is sad is the terrible way a major contributer to WUWT was lambasted just because the moderator didn’t understand or like what he was saying, even after another commentator had clarified Steves point (Scott says: September 1, 2010 at 4:00 pm). I think Steve deserves an apology.
Reopenned/new comments page is at:
http://wattsupwiththat.com/2010/09/01/open-sea-ice-thread/
Which posts were you commenting on? There’s only links to your own site…
Physics and chemistry of water
Density of water and ice
For most substances, the solid form of the substance is more dense than the liquid form; thus, a block of pure solid will sink in a tub of pure liquid. But a block of ice will float in a tub of water because solid water is less dense than liquid water. This is the first unusual property of water. At room temperature, liquid water becomes denser with lowering temperature, just like other substances. But at 4°C, just above freezing, water reaches its maximum density, and as water cools further toward freezing, the liquid water expands to become less dense. The physical reason for this is the related to the crystal structure of ordinary ice, known as hexagonal ice Ih.
This unusual expansion of water as it cools from 4°C above freezing to the freezing point offers an important advantage for freshwater life in winter. Water chilled at the surface becomes denser and sinks, forming convection currents that cool the whole water body, but when the temperature of the lake water reaches 4°C, water on the surface, as it chills further, becomes less dense, and stays as a surface layer which eventually forms ice. Since downward convection of colder water is blocked by the density change, any large body of fresh water frozen in winter will have the coldest water near the surface, away from the riverbed or lakebed.
Density of saltwater and ice
The situation in salt water is somewhat different. Ice still floats to keep the oceans from freezing solid (see following paragraph). But the salt content of oceans both lowers the freezing point by about 2°C and lowers the temperature of the density maximum of water to be about at the freezing point. Hence, in ocean water because of the salt content, the downward convection of colder water is not blocked by an expansion of water as it gets colder near the freezing point; so the oceans’ cold water near the freezing point keeps sinking. Thus any creature trying to survive at the bottom of the Arctic ocean is generally in an environment more than 4°C colder than the temperature at the bottom of frozen-over fresh water lakes and rivers in winter.
As the surface of salt water begins to freeze (at -1.9°C for normal salinity seawater, 35‰) the ice that forms is essentially salt free with a density approximately that of freshwater ice. This ice floats on the surface and the salt that is “frozen out” adds to the salinity and density of the seawater subjacent to it. This more dense saltwater sinks by convection and the replacing seawater is subject to the same process. This provides essentially freshwater ice at -1.9°C on the surface. The increased density seawater beneath the forming ice sinks toward the bottom, thus the deep ocean waters should have a minimum temperature of -1.9°C also.
Triple point
The temperature and pressure at which solid, liquid, and gaseous water coexist in equilibrium is called the triple point of water. This point is used to define the units of temperature (the kelvin and, indirectly, the degree Celsius and even the degree Fahrenheit). The triple point is at a temperature of 273.16 K (0.01 °C) by convention, and at a pressure of 611.2 Pa. This pressure is quite low and a pretty good vacuum, normal sea level barometric pressure is 101,300 Pa for comparison.
You are in error, you aren’t banned permanently. Your comments continue today at WUWT and I suggest that you resume the triple point of water discussion here.
Have people here not taken PChem or a chemical engineering-based thermodynamics class? The triple point that everyone here is quoting is for a PURE WATER system. No other gases/vapors present to complicate things. In a real-world system with an atmosphere, the phase diagrams do not apply!
steven Mosher Says:
September 2, 2010 at 2:43 pm | Reply
People just don’t get the difference between total pressure and partial pressure. Triple points CAN exist at higher pressure, and here’s the quote to prove it, from:
http://en.wikipedia.org/wiki/Triple_point
[EMPHASIS MINE]
If you don’t understand how the bolded sentence is possible, then you shouldn’t be engaging in the discussion until you do some background learning.
Funny, I just realized that Anthony copied/pasted the first sentence of that Wiki paragraph in his response to Steve, but conveniently ignored the game-changing sentence just two sentences later…
-Scott
Anthony –
I’ve been working on putting together an offline “proof” that I was going to send to CTM to show that Steve was (effectively) correct in the triple point discussion.
If I post it here instead (which would allow open dialog), would you be willing to read it?
I was very disappointed that WUWT closed this topic off for debated (though I understand why given the maturity of the conversation occurring). Having studied/tutored/taught this topic for 9 years now, I can easily show that Steve was (mostly) correct this time (and his opponents were very wrong).
If I can convince you, would you be willing to change your thread-terminating comment in the Sea Ice News #20 so that it gives the proper answer? I contend this would help reduce the embarrassment for WUWT.
Regards,
-Scott
Verdict is in on Tamino, and it is a mixed decision. He censored the first post but published the second one.
Gotta love free speech on the Internet.
I’m interested in seeing it Scott. The only key missing bit (IMNSHO) is a tabulation of humidity.
The jump from general thermo to chemical engineering thermo (aka mixtures!) blows a lot of people’s minds.
All this subversive talk about ice freezing and melting …… LOL
Steve,
Sorry for the foulup at WUWT
But, I was trying to point out that the seawater in the Artic under and amonst the ice is not at 0 C, it is colder than that due to the freezing point depression due to the salt in the water.
Congrats on your new blog
Steve,
As Anthony stated, you weren’t banned, so could you please make a note saying that in the article above?
Also, it’s my interpretation (feel free to pick it apart) that things went south at WUWT not because the triple point was being discussed but because of the way it was being discussed. Your method of debate often seems to involve one liners that to the laymen (or your opponent) are incomprehensible and/or insulting. I’m convinced that you understand the triple point issue at least as well as I do, and I believe that you could’ve made it 100% clear that you were right with a single, polite post with several paragraphs and plenty of links/references.
Just my thoughts,
-Scott
[OK I did an update]
People should really stop recycling that 6.1173 millibars BS….FFS….it is surely taught at high school that this does not refers to the total pressure of the overall system but strictly to the PARTIAL PRESSURE (pressure contributed by water vapour) of water, the vapour state being in equilibrium with the solid and liquid state. BASIC CHEMISTRY….READ A PROPER INTRODUCTORY BOOK ON PHASE EQUILIBRIA…and yes, this concerns also the world class statistician.
Bob Says:
September 2, 2010 at 5:23 pm | Reply
Yes Bob…I would argue that if people wanted to pick apart Steve’s triple point comment, this would have been the way to do it, not focusing on the pressure (which in fact should be partial pressure). This argument I would listen to, as it’s a much fuzzier topic. The pressure issue should be black and white.
-Scott
Alan S. Blue Says:
September 2, 2010 at 5:20 pm | Reply
Thanks for the interest. I’ll work on typing it up in a nearly-tutorial type approach. I’m extremely busy right now (and have spent too much time on this already), but I’ll try to put it together over the next few days. As for the humidity, I don’t have the answer to that. I assumed that relative humidity immediately above the ocean surface would be 100%, especially with average temps dropping in the Arctic. If you can provide a reference showing otherwise, I’d be convinced against my assumption. (Note that I made a similar offer to “jeez” on the WUWT thread, but it was right around the time of the closing of comments, so it never got posted).
Yes, I fully understand. When my ChemE thermo started with the word “fugacity”, that was a real eye opener (very painful one too). I took PChem the same term and found it much easier, LOL.
-Scott
Theorists arise!
Fresh water exists on the surface of the ice in all three phases at the pole during the summer. Does anyone really doubt this?
Scott,
Here’s the original quote of Steve’s on WUWT that got the triple point discussion going:
“If you look at 2006, extent dropped rapidly right before it flatlined. This year may be a repeat of that pattern. Given the triple point of water at 0C, the behaviour of the ice can change dramatically with a very small change in the weather.”
I think I roughly understand the two sides of the discussion that ensued regarding partial and absolute pressures. However, I’m not sure why Steve used “triple point” the way he did in the above statement. Could you (or Steve) elaborate on the difference between his statement and the much more obvious statement: Given the freezing point of water at 0C, the behavior of the ice can change dramatically with a very small change in the weather.? What additional possibilities does the existence of a “triple point” introduce? That’s what I’m missing from all this, because up to now no one’s pointed out any.
Rod
P.S. to Steve, I took jeez’s comment on WUWT about it being your last “thread” to mean that he thought you were moving the articles you post yourself to your own recently-announced blog. I don’t think he meant it in the way you apparently interpreted it, unless you had further background info that led you to that conclusion.
Rod
[Water exists in all three phases (solid/liquid/gas) at 0C. Sometimes in the winter you can see steam coming off melting snow in the roadway. Three phases coexisting is the definition of a triple point. In the real world, the triple point is a broad smear with hysteresis, not a sharp single point.]
Rod Everson Says:
September 2, 2010 at 5:40 pm | Reply
Rod, being at the triple point technically allows (in addition to melt/freeze) evaporation, sublimation, condensation, and deposition from the vapor phase. Honestly though, I think you’re right in that this adds little to the behavior of the system in this case (not in cases like Mt. Kilimanjaro) because of the small amounts involved. Someone please correct me if I’m wrong here. As you said, it likely would have been better said to just be stated as “freezing point of water”.
Steve appears to be a favorite target of many AGW believers, thus they jumped on his “the triple point of water”. Admittedly, when I hear that I think of the pure component triple point, which is the one everyone quoted, thus why I say that Steve is “mostly” or “effectively” correct. IMO, Steve would have been 100% correct had he said:
“a triple point of water”
OR
“the triple point of water at 1 atm”
OR (something along the lines of)
“conditions at which ice/water/water vapor are in equilibrium with each other”
Yes, very small differences, but people like to nitpick. Assuming the temperature is near 0 C, then the Arctic conditions are very much near the triple point of water at 1 atm (unless the relative humidity is low, which I doubt unless someone shows me data otherwise).
-Scott
[Water exists in all three phases (solid/liquid/gas) at 0C. Sometimes in the winter you can see steam coming off melting snow in the roadway. Three phases coexisting is the definition of a triple point. In the real world, the triple point is a broad smear with hysteresis, not a sharp single point.]
That part I understand (well, not the “broad smear with hysteresis” part, but the rest.) What I don’t understand is the distinction between the importance you apparently ascribe to the “triple point” as opposed to just saying the “freezing point.” Yes, the triple point exists, but just stating that doesn’t clarify why you bothered to say it in the first place. What happens at the triple point that makes it so important to emphasize rather than just saying the “freezing point” when you’re pointing out the potential effects of small changes in the weather? Why is it relevant to the discussion? That’s what I can’t determine from any comments so far, either on WUWT or here.
Rod
[Reply : The relevant processes near the triple point are not just freezing and melting. There is also precipitation (condensation) and sublimation (evaporation.) So it is a little more accurate to discuss all three phases rather than just two.]
[Reply : The relevant processes near the triple point are not just freezing and melting. There is also precipitation (condensation) and sublimation (evaporation.) So it is a little more accurate to discuss all three phases rather than just two.]
Okay, thanks Steve. I now know a lot more about the triple point than I did 24 hours ago.
Rod
I mentioned the partial pressure of water vapor very early on in the discussion before the thread was closed at WUWT…something a lot of the theorists living in a vacuum somehow didn’t ever mention.
As someone already stated above, a triple point of water can occur in real life situations like in the arctic provided the partial pressure of water vapor is .006 atmospheres. The actual total pressure of the system doesn’t have to be .006 atmospheres like some people were claiming.
Thrasher: “As someone already stated above, a triple point of water can occur in real life situations like in the arctic provided the partial pressure of water vapor is .006 atmospheres.”
No, this isn’t correct usage of the term “triple point”. Mr. Goddard incorrectly used the term triple point on WUWT, and the usage as in your quote is also incorrect. Triple point only refers to a specified physical system; if the system is specified only as “water” as in “the triple point of water”, then this statement is interpreted by scientists as a single component system comprised only of water. The triple point would be the point where all three phases exist in equilibrium, and this only can occur at an absolute pressure much less than atmospheric pressure.
If the system is a two or more component system, then the term triple point is rarely (never) used without specifying which other components are in the system. Scientists and engineers (chemical engineers like myself) work with multicomponent systems all the time, and don’t use the term triple point. Instead we use the term phase equilibria in systems where the components can exist as liquids and gases, or perhaps solids. But if some of the vapor components can not exist as either pure component liquids or solids, then we wouldn’t even use the term phase equilibria to describe the these systems and we would call the vapor components “gases”, not “vapors”. For example, we would describe air as being composed of nitrogen, oxygen, argon, and carbon dioxide gases, and water vapor, recognizing that the gaseous components do not exist as pure components in our system. We would not say that air is composed primarily of nitrogen,oxygen, and argon vapors, with some water vapor, and a small amount of carbon dioxide vapor. We would not say that when it rains, there is a “double point of water” day, or that water is liquifying; we would say that water is condensing. Likewise on a hot day, we wouldn’t say that water is boiling from a puddle; we would say the water is evaporating from the puddle. And we certainly would not refer to a misty day on the ice cap with melt ponds, an example of water at the “triple point”, as Mr. Goddard did in one of his comments. We wouldn’t even use a day like that as an example of water being present in three separate phases (at equilibrium) which is implicit in the use of the term triple point. But instead, realizing that pure water vapor (steam) dissipates rapidly and is not in an equilibrium phase state at the temperatures in the Arctic; rather we would talk about the evaporation of water, or the sublimation of ice (when the temperature is below freezing) in relationship to the air’s humidity (water saturation capacity). If the air is dry enough, some water from the ponds will evaporate, and some of the ice could sublime. Neither evaporation or sublimation are likely to result in significant losses of ice compared to ice melting and the resultant liquid water mixing with the Arctic Ocean waters.
So in spite of Mr. Goddard’s misuse of the term “triple point”, what was the point he was trying to make? He seems to postulate that the evaporation of water from the ice into the air is a significant mechanism for ice loss. Additionally he seems to believe that the sublimation of water vapor from the ice into the air is also an important mechanism. In order to address his concerns, we would need to address the heat transfer process where energy enters the Arctic ice pack system, and the mass transfer process where the water from the melted ice is transported and mixed with other fluids; either air as Mr. Goddard suggests, or seawater. I will attempt to address these concerns in my next comment.
But lets look past Mr. Goddard’s misuse of the term triple point.
[Reply: Wind is a key factor in melting ice, so sublimation is an extremely important process. If you lived near a frozen body of water you would be aware of this.]
Lets discuss the heat transfer process occurring in the Arctic ice pack, and how that relates to ice melt.
First, lets address Mr. Goddard’s assertion; that as long as the air temperatures in the Arctic are 0 deg C, there will be little ice melt. Mr. Goddard is overly focussed on temperatures, and not on the energy balance. He assumes that heat transfer from the air to the ice (and melt ponds) is the predominant energy transfer mechanism during the Arctic ice melt. This is not correct. The air temperatures in the Arctic don’t climb much above freezing, and so the heat transfer from the air to the ice has a relatively small temperature difference driving force.
But there are other sources of energy present in the ice cap. During the summer, sunlight strikes the ice cap at rates likely to exceed 200-300 watts per square meter and if absorbed, this radiant energy is converted to thermal energy. Most of the radiant energy is reflected, but some is absorbed. Does this absorbed energy melt the ice? If so, then how?
For most of the ice cap, there is a blanket of snow on top of the ice. The sunlight will hit the snow, and be reflected. Most will be reflected back up through the atmosphere, but some will be reflected into neighboring snow water crystals, and eventually a portion of that reflected light will be absorbed by water molecules in the snow and converted to thermal energy. Additionally, there will be some small dirt or soot particles on the surface of the snow, that will absorb most of the sunlight that hits them, and that radiant energy will also be converted to thermal energy. The melt ponds themselves will absorb more light that the surrounding snow and ice, and will add to the thermal energy flow into the ice cap.
The thermal energy heats the neighboring ice crystals, and will slightly melt a thin film of water on the crystals. At night, or cooler periods, when the flow of thermal energy into the ice cap decreases, most of the thermal energy added to the neighboring ice crystals moves into the cooler sections of the snow and ice pack, and the thin film of water re-freezes. Over time, the snow begins to resemble the spring snow conditions that skiers often encounter (and that clearly can be seen on the North Pole webcam at mid-summer). The net amount of ice melt due to this mechanism is still relatively small, but results in the melt ponds that show up across the ice pack from late June until early August.
If the air was supplying thermal energy to the ice pack, then the resulting thermal energy inflow would add to the thermal energy created from sunlight absorption, but neither of these two mechanisms seem to be the driving forces for Arctic ice melt.
So what is the source of thermal energy needed for the observed annual ice melt? I will address that in the next comment.
[Reply : Again, wind is a key factor in providing energy for ice melt]
Mr. Goddard, I just read your comment, where you again claim that sublimation is a significant driver of the Arctic ice melt. Try to calculate that… start with the assumption that the air blowing over the ice cap already is significantly saturated with water due to contact with the oceans and watery tundra surrounding the ice cap, so only an incremental amount of water can be absorbed by the air. This situation is unlike the dry air blowing off the Sahara and encountering warm sea water at air temperatures well above freezing, where the air can absorb a significant amount of moisture leading to fairly high evaporation rates from the ocean (per square meter of ocean surface)… The wind blowing over the ice cap is close to freezing and has a much lower water carrying capability (absolute humidity) and so the amount of water lost per square meter of ice cap surface should be relatively small. I would suspect the amount of water that the Arctic receives from freezing rain and snow in the summer exceeds the sublimation losses. The photos from the North Pole cam seem to corroborate that assumption, as we see periodic snow cover the ice pack around the camera.
Try some calculations of sublimation rate based on a relatively low humidity cold wind at 0 deg C, compare that to expected snow and freezing rain fall, and post this, if you would like. Then try to compare this sublimation rate with the annual loss of almost a million square km of ice pack several meters thick. It will be interesting to see how the ice mass loss due to sublimation (less precipitation), compares to the actual observed ice mass loss.
[Reply: I don’t think you are taking into consideration turbulence and mixing of the atmosphere. Most of the ice melt is at lower latitudes where warm, dry winds blow off the land masses. We saw lots of that in August this year.]
http://www.madsci.org/posts/archives/2001-04/987004615.Ch.r.html
Zinfan94 Says:
September 2, 2010 at 9:46 pm | Reply
“The air temperatures in the Arctic don’t climb much above freezing, and so the heat transfer from the air to the ice has a relatively small temperature difference driving force.”
Isn’t that a rather obvious subjective observation? Large parts of the Arctic do climb “much” above freezing, and much of that area is where the highest melt is seen.
I ran some made up numbers to see what I got. Assuming a perfectly dry column of air (doubtful, I’m guessing it’s near saturation) 100 meters high that then equilibrates with the ice would result in a loss of about 0.5 mm of ice thickness.
I don’t see why this is important to the discussion other than establishing that discussion of the triple point itself isn’t that important when discussing Arctic sublimation.
If thermal energy transferred from the air is unlikely to cause the observed ice pack melt, and even the amount of thermal energy converted from absorbed sunlight radiant energy seems to only cause surface melt ponds, with most eventually just re-freezing, then where does the thermal energy required to melt almost a million square km of ice cap come from?
Lets look at the sea water. First, the surface seawater on the edges of the ice pack is absorbing close to 90% of the sunlight radiant energy and converting that energy to thermal energy. This seawater may only be a few degrees higher than 0 deg C, but salt water can melt the ice down to lower temperatures (about 28 deg F). In addition, the high heat capacity of seawater (compared to air), combined with the huge mass flow of sea water washing up against the ice pack, and under the ice pack, will absorb a large amount of thermal energy from the ice. Eventually the seawater would cool down due to the loss of heat to the ice, but there is a replacement flow of seawater due to currents. And in addition to absorbed solar radiation in the summer, higher salinity seawater flows into the Arctic Ocean constantly throughout the year. An outlfow of lower salinity freshened seawater moves out of the Arctic at shallower depths. In effect, there is a large net inflow of thermal energy into the Arctic. These flows of seawater transfer heat into the ice pack from the bottom and sides, all year round.
In the winter, the very low air temperatures freeze the surface waters, and add to the depth of the ice thickness, because the heat is removed by the cold air more rapidly that thermal energy is transferred into the ice cap. During the winter, the sea surrounding the ice cap isn’t receiving any solar radiant energy, so the flow of heat into the ice cap falls off. But in the summer the heat flow in from the sea water increases, and the removal of heat from the ice cap by the cold air over the ice cap falls off. In the summer the temperature differential between the air and the ice is only a few deg C. In the winter the temperature difference can average over 30-40 deg C, so the heat absorbed by the cold winter winds, increases to much higher levels of heat transfer.
In addition, the ice pack fractures in the summer, particularly around the edges. In the winter in the ice pack itself there is little wave action, but during the summer large expanses of the ice pack around the edges are subject to wave action, with accelerated convective heat transfer rates.
The fact that most of the ice melt is due to heat absorbed from seawater, means that the ice melt season extends into late September, even though the solar influence is gone well before then. Only when the air temperature drops substantially below 0 deg C, does the removal of heat from the air counteract the warming of the ice pack from the sea water.
So Mr. Goddard’s theory of Arctic ice melt being primarily driven by heat absorbed from the wind over the ice, doesn’t hold up well, and is inconsistent with observations.
Oops, just re-read my last post, and I made one mistake that I need to correct: Seawater only absorbs 90% of incident sunlight when the sunlight enters the water surface normal to the surface… when the sun is lower in the sky, more of the sunlight is reflected off the surface of the sea, resulting in lower absorption.
In any case, clearly one of the primary sources of thermal energy that ends up melting the ice cap in the summer, is the absorption of solar energy by the mixed layer of the seas surrounding the ice cap.
Zinfan94 Says:
September 2, 2010 at 9:01 pm | Reply
So basically you agree with my comment here:
Scott Says:
September 2, 2010 at 6:10 pm
With the exception that you say that a condition where all 3 phases are in equilibrium is not a triple point unless it’s the pure component? Initially I thought the same, thus this post:
http://wattsupwiththat.com/2010/08/29/sea-ice-news-20/#comment-472674
However, I changed my mind after reconsidering. And I noted that it seems to disagree with this sentence:
From: http://en.wikipedia.org/wiki/Triple_point
I really think it all comes down to how strictly people interpret the “the” in “the triple point of water”. Replace it with “a” or add “at 1 atm” and the sentence is acceptable in my view. However, most of the commenters (or just one, “jeez”) seemed to be more interested in doing quick “Googles” to try to prove Steve wrong than to try interpret what he said in a reasonable way. And it ended with Anthony pasting a Wiki quote saying Steve was wrong whereas if he used that same quote and continued it for 2 more sentences it would have supported Steve instead.
-Scott
Man, I missed a /blockquote near the start of my last post (right after: “[lots of text not posted]”) and it looks horrible, LOL.
Scott, I get somewhat higher numbers than you, but we talking about several mm of ice loss due to sublimation (AND evaporation) each day or so, so over the course of 180 day at about 70 cm… but this is bone dry air…
A better estimate would be perhaps a 10% increase in relative humidity, which would put us at only one tenth that, or about 7 cm in 180 days; which is less than precipitation levels.
Steve needs to seriously re-think his arctic ice melt “ideas”.
Please see my new post :
http://stevengoddard.wordpress.com/2010/09/02/imagery-of-wind-melting-the-ice/
Heh. This reminds me of the old “natural dry ice at the South Pole” thread on WUWT. I’m glad I missed the triple point “discussion”. 🙂
Zinfan94 Says:
September 2, 2010 at 11:27 pm | Reply
“but this is bone dry air…”
http://nsidc.org/arcticmet/factors/humidity.html
Glenn, Scott and I used bone dry air (no water vapor) then saturated the air with water to 100% relative humidity to estimate the amount of water the air would pick up from the ice pack. The point is, the amount of ice lost due into the air due to either sublimation (when ice and air temperatures are below freezing temperature of water) or evaporation (the air saturates with water vapor from liquid water droplets or melt ponds on the surface of the ice), the amount is small compared to ice melt, even if we make the totally outrageous assumption that the air contained no water to begin with, and then absorbed water vapor until the air was saturated with water.
In reality, as your link shows, the air already contains a lot of water vapor, and the air over the ice pack is unlikely to become 100% saturated to 100% relative humidity over the entire summer. Therefore, the actual water absorbed from the ice pack by the air is likely less than 10% increase in relative humidity. Saturated air at 32 deg F holds about 2.5 pounds of water per thousand cubic feet of air. I used pickup of this entire amount to estimate the water picked up off the ice cap over a six month period to be approximately 70 cm of ice pack loss. In reality, if the air already contains 1.25 pounds of water per thousand cubic feet (40% relative humidity) and we increase that to 1.5 pounds per thousand cubic feet (50% relative humidity), then the wind only picks up about 0.25 pounds of water as it traverses the ice pack, and in this case, the ice pack would lose only about 7 cm (less than 3 inches) due to sublimation and evaporation. This rate is less than the rate of precipitation that falls on the ice pack in these six months, so sublimation and evaporation cannot explain the ice pack “melt”.
Clearly, the water from the ice is melting and running into the Arctic Ocean. The source of heat for this melt is unlikely to be the wind, since the air flowing over the surface of the ice pack is generally close to freezing on average; sometime higher and sometimes lower, but close to freezing. Even solar radiant energy absorbed by the ice pack can’t explain the bulk of the melting, although it is likely to be much higher than thermal energy sourced from the wind. The amount of thermal energy needed to melt approximately one million square kilometers of ice each year that is approximately six feet thick, must be coming from the sea water in the ocean. The sea water is transporting thermal energy under the ice pack and melting the ice.
Steve needs to realize this, before he goes any further down the dead end road he is on.
In reality,
Zinfan94
The air is constantly circulating, new air is arriving, and the ice isn’t very thick. The air coming off the neighboring land masses in August started out at 5-10C.
So how long does it take to replace the Air ? Say 10 days ?? (5000 miles at 20 mph)
= 15 to 30 inches in a Melting Season.
But remember the LIMIT to how much the Air can take, applies to this AND bright Sun sublimating the Ice to vapor.
>> They have to Share. << More, would force continuous Fog.
Let me repeat something cited by the 2007 Sea Ice update Redux: <http://www.sciencenews.org/articles/20071222/fob2.asp
… About 70 cm of that shrinkage resulted from melting of the ice's upper surface-a typical amount for the summer, says Perovich. However, a whopping 2 m or so of that erosion, about five times the normal summer loss, occurred from below”.
…. so 30" = 70 cm, from above, does seem to be a "typical amount for the summer". At least the numbers are not coming out of nowhere.
I don't know how to tell WHICH process is doing the melting, however.
Steven Goddard: I already assumed the air is changing, but the air in the mixed layer near the ground will have already reached a relative humidity that prevented more water absorption before it travels very far, using the fast evaporation calculation I have shown. My point was that the amount of water that can be removed from the ice pack due to evaporation and sublimation is likely less than observable precipitation. If you stop and think about it for a few minutes, you will see this makes sense. Water evaporates and saturates the air with water at lower latitudes where air temperatures are warmer. At 50 deg F, water saturated air holds over 6 pounds of water per thousand cubic feet or about 2.5 times the amount of water in the air at 32 deg F. Then this warmer air travels up over the ice pack and precipitates water and snow onto the ice. It is highly unlikely that the air will pick up more water from the ice pack than it precipitates, because in general the air is cooler over the pack than over the nearby seas and tundra.
Clearly the bulk of the water from the ice melt ends up in the Arctic Ocean.
Both extent and area are starting to rise now on arctic-roos nansen graphs, it seems that your forecast was right.
Dude, seriously.
Your “forecast” is a joke.
Don’t you know that yet?
The serious contributors calculated their forecasts and chose their methodology months ago. They did not jump in at the last minute and make a “forecast” that is nothing more than seeing the blindingly obvious.
Do you really think anyone is falling for it?
Fortunately, we have your earlier pronouncements on record. You weren’t so accurate earlier on in the melt season, were you, Mr “recovery, recovery, the ice is back”?
[Reply : Like NSIDC, Lindsay and Zhang, and many others, I made more than one forecast this summer. Mine were 5.5/5.5/5.1 (June July and August.) NSIDC made three 5.5/4.74/5.0 (June July and August.) I am playing by the same rules as everyone else.]
You evidently have a poor memory. Or did you just make lots of predictions and remember the ones that worked best?
Isn’t that how fortune tellers work?
[Reply : I have made two predictions this year 5.5 and 5.1. They are published in dozens of articles on WUWT. Feel free to use the search feature on WUWT if you believe otherwise]
Steven,
You were treated rudely and unfairly in the last SeaIce thread, and it is quite curious that everyone seemed to want to avoid answering your simple question of whether all three phases of water could and do exist in the Arctic. They do in many places in the world, if you believe in such a thing as humidity. Curiously, right after Anthony said “Note the pressure of the triple point at “T”. It is not an ambient earthly surface pressure” he also referred to “partial vapor pressure”… interpreting a phase diagram of water as representing a relationship between temperature and “earthly surface pressure” one would surmise that water vapor can not exist at all below 100C, since below the “1 atm” line vapor does not exist at any temperature below boiling.
On a phase diagram of water, the curve line representing vapor pressure to temperature below the triple point is actually called the sublimation curve. The line above is called the vaporization curve.
A phase diagram of water simply shows the vapor pressure of water as a function of temperature.
correction to my last post
“interpreting a phase diagram of water as representing a relationship between temperature and “earthly surface pressure” one would surmise that water vapor can not exist at all below 100C, since at no point on or near the “1 atm” line does water vapor exist at any temperature below boiling.”
It also curious to see that Anthony apparently understood vapor pressure/temperature relationship in the Antarctic thread:
“One small detail: partial pressure.
The concentration of CO2 in the free atmosphere is very small.”
http://wattsupwiththat.com/2009/06/13/results-lab-experiment-regarding-co2-snow-in-antarctica-at-113%C2%B0f-80-5%C2%B0c-not-possible/