Heat closes Antarctic ice runway

[Harry Hope]

Source: Herald Sun


January 05, 2011

Heat closes Antarctic ice runway

By David Killick From:Herald Sun


AUSTRALIA'S $45 million Antarctic ice runway has been unused this season because it is too hot. The 4km Wilkins runway, which opened in 2008, sits on ice 500m thick inland of Australia's Casey station.

But the Australian Antarctic Division's Airbus A319 has been unable to make a single flight this season because of warm temperatures. Instead, the aircraft has been shuttling between Hobart, Christchurch and the US base at McMurdo Sound 2100km east of Casey.

The division's director Lyn Maddock blamed unseasonally warm temperatures in Antarctica for the failure of the airlink.

"While the Wilkins Aerodrome is typically ready to start operations in mid-December, Antarctic weather conditions are notoriously unpredictable and factors such as blizzards and high temperatures can affect runway operations," she said. "Over the past few weeks ice temperatures at the runway have been above the critical threshold of -5C which means the structural integrity of the ice runway cannot be guaranteed."

Read more: http://www.heraldsun.com.au/ipad/heat-closes-antarctic-ice-runway/story-fn6bfm6w-1225981915861

[notadmblnd]

1. -5 celcius is not freezing enough to maintain ice?

how frozen is frozen?

[DavidDvorkin]

2. Frozen solidly enough to support the weight and landing gear, I guess.

[joshcryer]

3. Yeah the planes that they're landing there are pretty big.

Amusing that plowing down some ice costed them so much though.

[notadmblnd]

11. 500 meters thick?

isn't that 1500 feet of solid ice?

[DavidDvorkin]

13. Unless the temps are just under freezing

In which case, the top layers might not be solid enough. If the plane's wheels sank in during landing or takeoff, it could be disastrous.

[notadmblnd]

15. I'm just trying to understand

zero Celsius is freezing, wouldn't -5 Celsius be even colder? I can't remember the formula for converting from Celsius to Fahrenheit, but I do know that 32 degrees Fahrenheit equals 0 Celsius.

[Remmah2]

18. Salt water

The freezing point of open sea salt water is -2C. On the surface of ice, as water evaporates or sublimes the salt will concentrate further and the freezing point would drop even lower.

[notadmblnd]

20. that's a reasonable answer.

thank you very much for helping me understand why -5 is not cold enough.

[OnlinePoker]

23. It says "Inland" so it wouldn't be salt water that froze. n/t

[Electric Monk]

44. Antarctica has been surrounded by oceans for how long, again?

Pretty long, last time I checked.

[OnlinePoker]

45. So has Greenland...what's your point?

Except for right along the coast where there is ocean spray, there won't be salt water inland. The ice would form from accumulated precipitation. You do realize Antarctica is larger in area than the U.S., don't you?

[DavidDvorkin]

21. Yes, 0 Celsius is freezing, by definition

That is, it's the freezing point of pure water at sea level. At that location, and with the kind of water that's involved, the actual freezing temperature is probably a bit different.

But there's ice and there's ice. Ice that's at a temperature just under freezing, especially if there's also sunlight shining on it, may be softer than ice at a much lower temperature. In this case, perhaps soft enough that it would crumble under the wheels of a heavy transport plane.

[jberryhill]

27. No, it is a question of pressure

Water at atmospheric pressure is solid at 0 Celsius.

Water at 0 Celsius is not solid under the pressure of an A318 sitting on top of it.

[AtheistCrusader]

30. Bingo.

The plane can skid or hydroplane, and also can sink in a bit and have the wheels freeze solid to the ice if it stops moving for any reason.

[Xithras]

31. Yep, Pressure.

If I remember my physics classes correctly, you can calculate the freezing point of water under an aircraft using the Clapeyron equation. Of course, without knowing the specific weight of the aircraft, and the distribution of that weight across its various load bearing wheels, it would be impossible to calculate the exact freezing point required to land safely.

I'm sure the Australians have done the math, and I'd guess that the number is somewhere between 0 and -5 celsius.

[jberryhill]

32. the Clapeyron equation

[Xithras]

35. Lol! No, the Clausius–Clapeyron Relation

I was working from memory

http://en.wikipedia.org/wiki/Clausius%E2%80%93Clapeyron_relation

[DavidDvorkin]

39. Of course! I didn't even think of that. Duh.

[justabob]

43. there is also friction that has to be considered nt

[eyepaddle]

22. I worked in the Antarctic, the surface gets too pitted and rough and can damage

the aircraft.

When I was at McMurdo, we started the season at a runway on the sea ice (nice and smooth) and used wheeled planes on it until the temps got too warm and the surface becam unusable. Then operations shifted to Williams Field, which is a runway on packed snow (and thus only the ski equipped planes--like the C-130s from the NY Air Guard--could use it.)

At the tail end of the season they would strip off the snow from a third runway, Pegasus Field, which is on the thick ice shelf, so the wheeled planes--like C-17s could come in and take people home by the hundreds insted of 50 or 60 at a time like the 130s. During the warm part of the Antarctic summer (Dec and Jan) they left Pegasus covered in snow so the surface wouldn't pit and rut.

This was close to 10 years ago, though, so I think they have changed their operational patterns some, but I am pretty sure this is what the Australians are dealing with.

[dipsydoodle]

6. Depends partly on

humidity and air pressure. Water only freezes at 0 celcius under normal conditions. Frost doesn't form in deserts for example until well below -5.

[notadmblnd]

9. in the desert though, I would imagine the lack of frost is a result of a lack of moisture

no?

[muriel_volestrangler]

16. Strength of ice, like many materials, becomes much lower near its melting point

and also the pressure exerted by the plane under its landing gear might be enough the locally melt the ice at that point - turning the landing gear into skates, basically.

See eg figure 4 here: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA333030&Location=U2&doc=GetTRDoc.pdf

If they built it assuming the friction they'd get from very cold ice, they might not be able to stop in time when its close to melting without a plane skidding along it.

[freedom fighter jh]

34. Like ice skates

Ice skates work by creating pressure high enough to melt a thin layer of ice just under them. The pressure is high because the skater's weight is distributed over a very small area -- the part of the blade that makes contact with the ice.

[dipsydoodle]

19. Exactly - low humidity

However - the same applies to Antarctica which apparently has the lowest humidity on earth at 0.03 %. I think that's because there is zero rainfall and the air is bone dry.

:hi:

[jberryhill]

26. Consider how ice skates work

Solid water, unlike many solid materials, can be converted to the liquid phase by pressure.

That is why ice skates work. The pressure exerted by your body weight over that thin blade, actually melts the ice right under the blade, so that the skate can... skate.

Same deal with the landing gear of an airplane.

An A318 is a heavy thing, and all of that weight is concentrated by the landing gear, creating considerable pressure beneath the gear when it touches down.

In order to prevent that, you need to be well below freezing to compensate for the position on the phase chart.

Here, this drawing should explain it to you:



The negative slope of the solidus line is the problem.

[Bandit]

42. Salt water freezes at a lower temperature than normal water.

:shrug:

[truthisfreedom]

4. It's called global warming for a reason.

Unseasonable is the word of the day.

[Uncle Joe]

5. Kicked and recommended.

Thanks for the thread, Harry Hope.

[Harry Hope]

28. This was too important to get lost. Not covered by the MSM.

[Speck Tater]

7. This could be also bad news for "Ice Road Truckers" in years to come. nt

[Lautremont]

8. It already is.

The ice road season, already short, has been reduced in recent years by weeks, at least in Northern Manitoba - this is the only way some northern communities get their supplies. If you're into investing, airship technology would not be a bad consideration, as that's what's going to provide a good deal of northern cargo transport in the future.

[Roland99]

10. I just read Crichton's State of Fear

wonder how he defends his position when news like this is continually released?

[hatrack]

12. He's dead, which saves him much effort in doing so . . . .

nt

[Roland99]

14. ha

oops. didn't realize that. :)

[Joanne98]

17. I hope this is the end of Ice Road Truckers.

What a stupid show.

[Javaman]

24. Isn't it summer in the souther hemisphere? nt

[XemaSab]

38. Yes, it's summer there

but "summer" is relative. Also, they're still two months from the highest temperatures.

[FLAprogressive]

25. But it SNOWED in AMERICA during WINTER....NO GLOBAL WARMING

[caraher]

29. I'm not sure there's much cosmic significance here

It is summer there, after all, and this facility only opened in 2008, so it's not as if an airstrip that had been in routine year-round use for decades is suddenly unusuable.

And yes, global warming is real and human-caused and I'd even say THE most pressing of our environmental problems. To the extent that this was an unforeseen shutdown the problem lies mainly with the planning of whoever thought they could use it year-round when it opened 2-3 years ago than anything else.

[Uncle Joe]

33. That begs the question of how in depth their climatic research of this area was

before they built the airstrip?

But there are other canaries in the coal mine down under and I wonder if the Antarctic warmth as exemplified by this fragile airstrip has contributed to the record breaking floods in Australia?

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=102x4679204

[LawnKorn]

36. They listened to the deniers and blew $45 million on an airstrip that can't be used because of GW

This is a fine example of the people who refuse to believe science coming out on the losing end of things. If they ignored science and a bridge fell down, people would be in court.

The stupid voters in the United States have ignored the results of the Bush Administration and voted the Republicans back into office. We will be paying for that stupidity for years to come.

[Hugabear]

37. Bet you this won't make Drudge Report

But let it snow somewhere Minnesota during the winter, and you can be sure he'll be all over that.

[bongbong]

40. A plot

It's a plot by Antarctica to get more grant money.

[OnlinePoker]

41. They say above normal temperatures, but NOAA says not.

I'm not sure where in the Antarctic this station is located, but for the last month, the majority of the Antarctic has been below to well below normal for temps. Here's the animation:

http://www.esrl.noaa.gov/psd/map/images/fnl/sfctmpmer_01a_30frames.fnl.anim.html

Also, just to be picky, the photo in the article is not of this station; there are trees in the background.