# How fast and how coarse does a sandstorm need to be to sand a human down to nothing in the span of an hour?

I am designing a world with extreme weather, which uses human survivability as a measure of time. I've equated something close to an hour for the time I am using, for simplicity's sake, but this poses a significant problem in terms of just how violent these conditions need to be. I'm not all that intelligent with erosion and bone density and it's a pretty specific thing to ask. So I'm asking here to get an answer. Additionally, how long would - say - a sheet of Tungsten and an average granite mesa last in such conditions?

• I am struggling with how to answer this in any way that would be useful for any use of fiction. "The sand is only 160 grit today, so we can last an extra half hour before we are nothing". It seems like this is the sort of scenario where the wind and grit can do what is requested. Youtube does have a video of sandblasting a watermelon for anyone interested. May 21 at 21:15

Not possible

The problem here is that in order for an abrasive substance to quickly damage an object, it has to be moving at high speed relative to that object. Which is a problem because a human body will simply be blown over once the wind speed is over about 20 m/s and potentially picked up and blown away at 30-40 m/s (as per this Physics SE question). This limits the relative speed of the abrasive particles to <30 m/s with respect to the human body, which simply isn't enough to massively damage the soft tissue over the course of an hour, let alone abrade away the bone.

As per this XKCD What If, humans can survive brief exposures to 500 mph (approximately 800 km/hr) winds when ejecting from aircraft, although the link lacks data on ejecting into a dense sandstorm.

Note that "human survivability" is generally defined as "still possessing life signs" rather than "entire human body has been reduced to sand-sized particles". Hurricane-strength winds or even lesser storms can kill humans by either smashing objects into a human body or propelling a human body into a relatively immovable object. Having the survival scale as "mean time before lethal wind-driven impact" would be a useful measure and drop rapidly to only a few seconds as winds pass the point at which even a heavy person will be blown off their feet.

• I don't go along with this. A human body is heavy. As the body is being blown along, the wind is still travelling much faster and the body is tumbling over the sand, so abrasion will occur. I suspect that the body will soon become flayed. May 21 at 11:21
• @chasly-supportsMonica a human body is heavy, but it's not heavy enough to remain on the ground if the wind is strong enough to drive particles at "strip the flesh within an hour" speeds. Short of a windstorm that first encloses its victims in tight-gridded mesh cages to hold them stationary with respect to the wind-blown particles it's just not possible. Further, it's a "black swan" argument but of all the people killed in hurricanes, tornadoes, sandstorms, blizzards etc I haven't found a record of a single one "flayed". May 22 at 1:52
• I have also mentioned that the actual grade of the substance in the wind is something I'm asking for (read "how coarse") so you can consider it anywhere between fine powder and fist sized shards of rock when making any assumptions. I guess the average piece being moved in the wind is arrowhead sized? And equally shaped. May 22 at 9:52
• @KerrAvon2055 - You speak as though you have great authority on this subject - do you? Have you done, or can you cite any research on the subject? If so, it would be fascinating to read. Historically, science is full of guesses that proved to be wrong when the experiment was actually carried out. May 23 at 23:42
• @chasly-supportsMonica please have a look at allthatsinteresting.com/…. I suggest that Mount Everest may be known to have rather strong winds blowing ice particles around fairly often. I'll let the images and descriptions of the actual bodies in the story, especially that of George Mallory as it was found 75 years after he died, speak for themselves. In case of link rot, searching "corpses on Mt Everest" provides ample alternative sources. May 24 at 11:42

I wonder how exactly would you implementing Human Survivability as time measuring system.

Would each and every situation measure time in different units? In desert would they be measuring with “Sandstorm Units” and in Artic with “Frostbite unit”. What about bullet shots which possibly kill in fraction of seconds when placed right. Knife stabs, Sword Slash, Infections, Diseases etc?

Time is an important measurement. You can get by vague estimations in daily life. But for traders, navigators, armies, explorers, adventures and many more, inaccuracy of mere minutes to an hour can cost profits, conquests or even life.

Also even in exactly same situation, each human last longer, so which one is gonna be the standard. And how exactly are people gonna relate to the time measurement if they haven’t seen a human die in time unit scenario.

Here, with pendulum clock, you have seen how long it takes for it to swing, and know the feel of a second, while hours being estimated from daylight and sun.

Also, time measuring devices like clocks and watches. Here, we have used sun, pendulum oscillation, spring oscillation, atomic oscillations etc to measure and define time. How exactly could human survivability be measured? You can’t exactly use seconds or hour of our world, or any time unit for that matter, since you don’t have any other units besides Human Life.

So, you should, firstly, clarify or rethink your time measuring system , before moving on to sandpapering humans.

• Trust me, I have thoroughly thought out the time system; the planet is in an equivalent post-disaster colonial era, tidally-locked, and has no tilt. The sun doesn't move, atoms haven't been discovered, pendulums are legitimately too studious to be widespread in a society in significant decline, and there are no seasons. Surviving deadly wind speeds is an important thing to know for this society considering it's an almost universal and constant conflict, so it defines "how long should I stay out in this." The context of the question doesn't really change what I'm asking. May 22 at 9:45
• Alright then. But still, how would wind survival be used as time measurement, can you give an example of usage. May 26 at 0:36
• "We can pass through the storm, so long as we don't take a (sand)hour." "Why a sand hour?" "That's how long it'll take for it to completely sand us into nothing." Culturally, knowing how long you can survive inside a storm becomes important to nomadic folk, until it becomes applied to daily life. You work with what you have, and these folks don't have crop cycles or lunar phases to follow. In an otherwise unchanging landscape, this is the only thing that changes with time, and thus is comparable to time. They probably have hourglasses specifically for storms but which they can then use later May 26 at 5:32

Q: I am designing a world with extreme weather, which uses human survivability as a measure of time.

## Dig them in

Suppose this wind is constant and you have many thousands of prisoners you can use for 24/7 time measurement. Dig a hole, put them in with only their head sticking out.

How long it would take.. difficult to determine. On your planet, each subsequent hour would be defined as the time it will take for the current prisoner to die. As prisoners differ, the hours would vary as well !

(don't try this at home)

• The concept is not how long it takes them to die; it's specifically, how fast it must be to to erode a human body, verbatim. As though it were a rock, so yeah, probably wedged somewhere in the ground May 22 at 9:48