I suppose this is scientific/math question! I'm wondering why -- by the time the Accidental Magic Reversal Squad reached Aunt Marge after Harry accidentally inflated her with magic -- Aunt Marge didn't freeze to death. How high into the sky would Aunt Marge have had to have floated in order to experience fatal hypothermia? It seems she floated up, but sideways, as she was easily located (over Sheffield, IIRC), and then deflated and her memory modified. Would Aunt Marge be akin to a helium balloon rising into the sky? Anyhow, the question is:

After being magically inflated, how high into the sky would Aunt Marge have had to have floated before freezing to death?

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    Depends, was she full of hot air? – Kevin Mar 12 '12 at 20:18
  • I think any serious question is going to have to approach this form the magic point of view; what is inflating her? – AncientSwordRage Mar 12 '12 at 20:35
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    More importantly, how would she die first? Freezing, or suffocation? – Iszi Mar 12 '12 at 21:01
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    @Kalissar - Both title styles are technically correct. I brought this up in meta because I was finding that people were editing my titles quite frequently. The title style I use is called the headline style. It is perfectly correct. The other style is called the sentence style, which is also perfectly correct. I'll leave the corrections you've made so far, but they're not really necessary; it's a style preference. Check out on my meta post on it, where I quote The Chicago Manual of Style. Thanks! :) – Slytherincess Aug 24 '13 at 0:21
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    @Kalissar - I actually started using the sentence style title because it seems our community is more amenable to that style, and if it makes someone more amenable to considering my questions, I really have no problem with it :) – Slytherincess Aug 24 '13 at 0:25

To get a specific answer you would have to know the ground temperature, how many layers of clothing Aunt marge was wearing, her rate of rise, her rate of heat loss, the height of the troposphere over England, and the weather in the upper troposphere.

Since we don't have any of that let's hazard a guess with the help of UK Weather online and a few random variables. We'll assume there is no wind chill factor for one. We'll put the rate of rise as 1m/s and Heat loss based on this math which I am not doing and you can't make me.

According to this chart:


After about 17 minutes Marge would be around 1km high. It would take another 17 minutes to hit the 2km mark. At around 2km the temperature is 0c (32F), the freezing point of water and humans. (Hey we are ugly bags of mostly water after all.)

If we assume a constant rate of ascension as 17 minutes per kilometer she will spend another 68 minutes getting to our next benchmark.

At close to 6km the temperature has dropped to 20c (-4F). Keeping in mind that hypothermia begins when the body's temperature hits 35c (95F) it would be safe to say that she was suffering at this point from hypothermia. Now if she doesn't suffer from paradoxical undressing and take off all her clothes she will continue to lose heat at the same rate she has been.

At 9km and -40c (-40F) she will have spent almost two full hours at below freezing temperatures. By this point the shivering stage of hypothermia would have set in and her body will begin to shut down. That's provided she has no underlying health problems because ventricular tachycardia or atrial fibrillation can also set in with severe hypothermia.

At about 12km the temperature has dropped to -55c (-67F) and Aunt Marge has spent another 51 minutes in the cold. She is now a corpse balloon.

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    +1 and accept -- and I won't demand that you do the math :D – Slytherincess Apr 26 '12 at 3:50
  • Actually, she'd be dead much sooner. See my answer. – SQB Apr 16 '14 at 9:51

As you go up the air gets thinner. As the air gets thinner eventually you reach a point where you are at the same specific gravity as the air you are displacing. At this point you stop rising and float.

How high she could go would depend on the air temperature. Generally you can go up about 10k feet before it starts to get real cold no matter the ground temperature.

  • You wrote: Generally you can go up about 10k feet before it starts to get real cold no matter the ground temperature. It would be great if you could provide a source verifying this info. Add it in if you can! :) – Slytherincess Mar 12 '12 at 21:09
  • @Slytherincess: Just climb a 10,000 foot mountain! My sister has a ski-lodge at 8,500 feet and during the summer it's warm there, and also at the top of the ski slope, which is at 10,000 feet. – Tango Mar 12 '12 at 21:49
  • @TangoOversway - Just remember which state I'm in! We've got the Fourteeners! (For the record, I would die if I tried to climb a mountain of any height; I'm completely NOT outdoorsy, LOL!) – Slytherincess Mar 13 '12 at 11:02
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    @Slytherincess - Then you know there is snow at the top of those year round. To freeze to death you need a temperature below freezing. Yes it can be warm there especially in the summer near the ground. But if you get a hundred feet or so above the cover and its much colder. But there is no set layer where the temperature is 32F(0C) all the time because of the nature of weather. I really only know this because 10k was our ceiling for jumping with out special gear and know it was pretty cold up there. Legions answer above puts it at about 8500ft. – Chad Mar 13 '12 at 13:01

As always, there's a relevant xkcd, but this time, it's a What If?

The question is asked,

If you suddenly began rising steadily at one foot per second, how exactly would you die? Would you freeze or suffocate first? Or something else?

Of course, this supposes rising at a steady rate, which may or may not have been the case with aunt Marge, who may have risen like a balloon, slowing her ascent, until she floated at a certain height.
Actually, hopefully she did, as we'll see shortly.

As Randall notes, it gets cold up there, but not too cold:

If you were nude, you'd probably succumb to hypothermia somewhere around the five hour mark, before your oxygen ran out. If you were bundled up, you may be frostbitten, but you would probably survive ...

... long enough to reach the Death Zone.

At 8,000 meters, the oxygen content in the air is so low, your lungs no longer take oxygen from the air — they lose it to the air. You suffocate.

†: Not related to the Twilight Zone. It's not a journey into a wondrous land of imagination. You're not moving into a land of both shadow and substance, of things and ideas. You just die.

If we accept Legion600's rate of ascent of 1 meter per second, she'd be dead in 8000 seconds and a bit — two hours and a half, at the most.

If we accept Pureferret's time to reach Sheffield, alive, it means she hadn't reached the Death Zone yet. This puts her rate of ascend (again assuming a constant rate) much lower than 1 meter per second, lower than a foot per second even. To travel 8 kilometers in 18 hours, you would have been traveling at the wonderfully magical sounding rate of 0.12345679 meters per second.
Unfortunately, this would put her in the cold zone much longer, so she would've frozen to death after all.

Going back to Randall's article, we see that the temperature is low, but bearable at about 2000 meters (roughly 6500 feet). To reach that height while ascending in a steady rate, while still traveling 10 miles per hour horizontally, she wouldn't have been rising, she would have been going off at an angle, almost horizontally even.

So we in conclusion, she probably rose pretty much like a balloon, quickly at first, but steadily slowing her ascend until she reached a height of about 2000 meters at the most, where she floated, drifting to Sheffield.


The main thing to consider here is the lapse rate and the rate at which Marge Floats.

Reviewing the footage from the film, and some simple calculation leads me to believe that she is magically lifted as opposed to it being a simple matter of hot air and bouyancy. Thus she would never reach the point where the mass of the volume of air she displaces is equal to the her mass, and thus she should continuously rise. Because of her magical lift, she would ascend at a linear rate (as opposed to accelerating). It's also noted she's found floating above Sheffield, some 180 miles away.

Taking form the Hot Air Balloon page on wikipedia we find this:

Most hot air balloon launches are made during the cooler hours of the day, at dawn or two to three hours before sunset. At these times of day, the winds are typically light making for easier launch and landing of the balloon. Flying at these times also avoids thermals, which are vertical air currents caused by ground heating that make it more difficult to control the balloon. In the extreme, the downdrafts associated with strong thermals can exceed the ability of a balloon to climb and can thus force a balloon into the ground.

I've highlighted the relevant bits. So there are no thermals forcing marge up or down.

I've found a page on wind speed in the UK, it's not conclusive but I'd estimate that she travelled around 10mph horizontally, meaning it should have taken her 18 hours to reach sheffield. If this is possible between the time she left Surrey and the Cornelius talks to Harry about this I'd imagine her vertical height was also magically determined, otherwise she would be too high up to recover.

Harry only wants her to be pushed away (not pushed up, but away) because she's just full of hot air. I don't think her climb would be completely uncontrolled, and I don't think she would ever reach the point of death.

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