Superheating sand

[Django]

Hi forums

 

I wonder if anyone can help me with a story i'm writing. I'm no scientist but I like fiction to have a basis in real life, and theres an event in the story that i'm not quite sure of what the effect would be.

 

Say that every year or every few years, an area of earth is scorched by some kind of superheated power- perhaps similar to when lightning strikes the ground, but much more powerful, a much larger area of effect, and lasting for much longer than a quick lightning strike- say a minute or two.

What would happen to the area of earth, and what would happen to it over a long period of time?

 

Also, what if the area was sand instead of earth? Would it become glass?

 

Please let me know if anyone has any ideas or opinions on this as i'm sure you're all far more qualified to answer than I am. Also, my apologies if this is the wrong forum.

 

Thanks

[ajb]

Meteorites that hit sand can create glass beads. Look up Dakhla glass in Egypt.

 

Superheating has a very specific meaning in physics. Basically it refers to heating a liquid to a temperature greater than its boiling point without actually boiling. That is the liquid remains a liquid.

Edited February 20, 2012 by ajb

[qsa]

http://en.wikipedia.org/wiki/Space-based_solar_power

[md65536]

What would happen to the area of earth, and what would happen to it over a long period of time?

 

With enough energy the area of Earth could be vaporized.

 

I've heard of this before in fiction, perhaps in the Mars trilogy... http://en.wikipedia.org/wiki/Mars_trilogy

I think they had satellites set up to purposefully vaporize strips of the Martian surface, as part of a terraforming effort, to increase the density of the Martian atmosphere.

 

 

[Django]

Thanks for your responses, got some good ideas from researching the things you all suggested.

 

I wasn't aware that superheating was already a term- it can hapen to water in a microwave right? The Dakhla glass was fantastic, very glad to have seen that.

 

And if the area of earth could be vaporized by the energy, then would it eventually become a large crater with repeated intense strikes? Also is the Mars trilogy good? Havn't read them.

[md65536]

And if the area of earth could be vaporized by the energy, then would it eventually become a large crater with repeated intense strikes? Also is the Mars trilogy good? Havn't read them.

I imagine it would be similar to burning away the surface of anything... wood with a magnifying glass, or metal with a welding electrode, etc. What the damage looks like would depend on how and where the energy is focused.

 

The Mars trilogy is amazing. It seemed very "realistic", like a visionary colonization of Mars is the story, rather than just a backdrop for a sci-fi story. It was filled with a lot of really colossal ideas.

 

 

[ajb]

I wasn't aware that superheating was already a term- it can hapen to water in a microwave right?

 

I guess so. Superheating happens when the liquid is homogeneous and the container is very clean.

 

When boiling a liquid it is small particles of dirt that instigate the nucleation of bubbles and then the sample can boil. You can also get this nucleation if the sample is disturbed. So if you can carefully heat a sample of liquid in the right way without any inhomogeneities you can superheat it past the usual boiling point.

 

The same thing can happen in the other direction. You can supercool liquids. This is a lot of fun to see. If you place a bottle of spring water in your freezer and leave it for a few hours, taking care not to disturb it, it is possible to get the water below the temperature of freezing keeping the water liquid. If you get to this stage, carefully remove the bottle and shake it or open it. The water turns to ice in a few seconds quite dramatically.

 

You need small inhomogeneities, like impurities to "seed" the formation of ice crystals. Without these and without disturbances water can be cooled to below zero Celsius.

 

Try it, it is far safer than superheating water. You may be able to find clips on youtube of this, I have not actually looked.

 

 

The Dakhla glass was fantastic, very glad to have seen that.

 

This was a mystery for a long time. People found glass beads in the middle of the desert. We now know how they were created.

 

So, it is quite plausible that some high energy beam could create similar glass beads if focussed on sand. I assume one could do some sort of calculation here and get an idea on how powerful such a beam would need to be. Something to think about anyway.

[CaptainPanic]

Superheating has a very specific meaning in physics. Basically it refers to heating a liquid to a temperature greater than its boiling point without actually boiling. That is the liquid remains a liquid.

 

What ajb says it 100% correct. But I'm gonna confuse matters a little...

 

Inconveniently, a "superheater" is a device which can turn saturated steam into dry steam (i.e. steam so hot it first needs to cool down before any condensation can happen). So, superheated steam is a term often used for steam (a vapor, not a liquid!) above its boiling point.

[Django]

I think i'm going to go with the area becoming a large, smooth crater of black obsidian-like glass. New sand and dust that enters the area between heat-laser events would be melted into the surface and it would be re-smoothed each time, maybe.

 

Thanks for all your responses, really helped shape the idea. And i have Red Mars on my wishlist, and learned about superheating.

 

Great forum, I may be back with more questions. Cheers

[CaptainPanic]

I think i'm going to go with the area becoming a large, smooth crater of black obsidian-like glass. New sand and dust that enters the area between heat-laser events would be melted into the surface and it would be re-smoothed each time, maybe.

 

Thanks for all your responses, really helped shape the idea. And i have Red Mars on my wishlist, and learned about superheating.

 

Great forum, I may be back with more questions. Cheers

Nice that you dropped by another time to say thanks, and to confirm that you read our contributions.

 

Reading your opening post again, I wanted to add something...

 

Say that every year or every few years, an area of earth is scorched by some kind of superheated power- perhaps similar to when lightning strikes the ground, but much more powerful, a much larger area of effect, and lasting for much longer than a quick lightning strike- say a minute or two.

What would happen to the area of earth, and what would happen to it over a long period of time?

 

Also, what if the area was sand instead of earth? Would it become glass?

It would be really hard for that much charge to build up in the atmosphere. You probably already realized that your story doesn't work with ordinary lightning, even in the most unrealistically bad weather.

 

But just for fun, I was wondering how many ordinary lightning strikes you would need to create a real lava lake (turning rock into molten rock).

A lightning strike contains a few million Joule (let's say 100 MJ).

If your area where is strikes is 10x10 meters, and 1 meter deep (i.e. 1x10x10 = 100 m3), you have to heat up 100 ton of earth by about 1600°C. Since sand (SiO₂) has a heat capacity of 830 J/kgK, you need 133 GJ. That would mean you need about 1330 lightning strikes to get it that hot... and remember that this is only for a tiny area of 10x10 meters, and only 1 meter deep.

 

(And that's assuming that (1) that's a pretty awesomely big lightning strike, (2) they send all the energy into the earth, and not into the air itself, (3) that hte strikes happen so quickly that the earth cannot cool down... oh, and I simplified the thermodynamics a little (a lot)).

 

If you read those assumptions that I had to make, we can rest assured that mother nature is not going to create lava lakes with lightning.

[Django]

Well actually the heat event is basically a gigantic space laser, created and magnified through orbiting crystal moons; it happens every so often when they align in the right way. I used lightning as an example because after doing some quick research on lasers, I learned that they mostly don't get that hot, and sci-fi style heat lasers are a long way away. Lightning seemed to me to be an appropriate example because of what I had read about what happens when lightning strikes the desert, but I guess it may have been confusing.

 

But maybe it would still have some kind of effect on the atmosphere like lightning does?

[ajb]

Well actually the heat event is basically a gigantic space laser, created and magnified through orbiting crystal moons; it happens every so often when they align in the right way.

 

 

Look up a star called MWC 349.