exchemist

What does this tell us about the mechanism by which charge separation takes place in thunderclouds?

I wonder if this is to do with the wording. They say 22kJ is expansion work done "on the system". They don't say 22kJ of expansion work is done by the system. Presuming "the system" means the reactant and products, I'm confused as to whether the atmosphere does work on the system, i.e. the volume decreases in the course of the reaction, or whether the system does work pushing back the atmosphere, i.e. the volume increases. If the volume increases, then I agree the internal energy change must be enough to supply that work AND still give you a measured heat output of 15kJ.

From my experience in the oil industryI'm aware of static generation in insulating liquids flowing in a pipe or in charged droplets in water sprays, used in tank cleaning etc, but I don't believe I've come across the idea that liquid falling through air does this to a significant extent.

Cloud to cloud discharges are extremely common in thunderstorms. But my interest is in the charge separation mechanism. Handwaving about the triboelectric effect (which by the way also seems poorly understood) doesn't seem to help very much. Regarding cloud to ground discharges, my understanding is that it is the charge separation within the cloud which causes a polarisation of the earth beneath and that is what leads to a lightning strike. I've never heard of any triboelectric effect involving the earth (what would "rub" against the earth and how would that work?).

It may be but it seems to address a different issue, viz. how the lightning discharge occurs. Does it actually discuss the mechanism of charge separation? I'm not going to waste time watching a video that may be irrelevant to what I'm trying to understand.

Due to a question asked on another forum, I tried to look into the mechanism by which charge separation takes place in thunderclouds. To my surprise it seems we still don't know how it happens. I found this paper, summarising the various hypotheses and the drawbacks of each: https://www.researchgate.net/publication/227134643_Charge_Separation_Mechanisms_in_Clouds Apparently the leading hypotheses are an inductive mechanism, relying on polarisation of liquid water droplets and one involving charge transfer between "graupel" (soft hail) and ie crystals. The inductive hypotheses relies on the idea that the electric field within the cloud (+ve at the top and -ve at the bottom) polarises the larger droplets, which are falling under their weight, so that they become positively charged at their base. When they encounter small droplets, which are rising due to the convective updraught in the cloud, they abstract electrons, leaving the small droplets with a +ve charge. So this leads to a further accumulation of +ve charge at the top and -ve at the bottom, further strengthening the electric field and so on. The ice one was more intriguing. Experiments at Manchester University have apparently shown that when falling lumps of graupel contact ice crystals, charge tends to be transferred, the extent and polarity of the transfer depending on the temperature. I found myself wondering why there should be a difference in tendency to lose electrons - or protons - (it is unclear which are the charge carriers in the interaction) - between crystalline ice and the presumably more amorphous ice in graupel. I wonder if it may be to do with the edges and vertices of crystals. There will be unsatisfied valencies there, since the molecules at such locations are not fully bound into the lattice in all directions. The paper doesn't go into this, being more concerned with the physics of the overall process. Anyway, it seemed interesting that this is not yet well understood. I wondered if anyone here might know more about the subject.

Metallic gallium seems to have low toxicity. From what I read it behaves more or less like Fe in biological systems. I don't think handling a bit of it will do any harm.

Eh??

Re your (1) no, any ToE will remain subject to the possibility of refinement, modification or rejection, in case there may one day be new observational evidence that does not fit with it. Science aways stays open-ended, as we can never know there are no more novel observations to be made. Re your (2), never ending exploration has always been a given in science: it is intrinsic to what science is.

You've already got one thread on this subject AND you've been told not to just attach files with no explanation. Reported.

Ah, so the meringues I make are hardened against an EMP, then. Good to know.

White objects do not absorb , or not much, in the visible region of the spectrum. But UV, as the name implies, lies outside that region. So visible colour is no guide. White clothing absorbs less visible light, which indeed makes it heated less by sunlight.

You can never make such an assumption, so this scenario can never arise. This is because It is never possible to prove a scientific theory true. So we can never state with certainty that there is no more to discover.

Well, you've had your answer from the people here. Your idea about making soil fertile by passing CO2 into it is misguided and won't work. Plants do not take in CO2 via their roots but via their leaves. As for "....the breakdown of raw elements into the dirt, with water and carbon (along with other chemicals) being pupmed under pressure into the churning mix", that does not describe anything coherent enough to comment on.

Passing CO2 over poor soil won’t improve its fertility, but increasing the CO2 content of air in a greenhouse does accelerate growth. This has been widely done for years in the Netherlands, where a gas engine is used to generate electricity to light them in winter months, exhaust is used to promote growth and waste heat to warm them. This is done commercially to produce tomatoes, capsicums etc all year round for supermarkets.

I still have those massive iron fireplace surrounds in the upstairs bedrooms in my late Victorian (1897) house. I was surprised to find, when planning some redecoration, that the mantelpieces are all magnetic.

Why should we do that when it obviously won't work?

Ah. Magnets. And harvesting energy. Does Tesla come into it at any point? Just asking.

Are you seriously arguing that because the average air temperatures are different, there can't be any effect of air temperature on soil formation? Why consider the average? Why not the annual range, for instance? Or the difference between day and night? Aren't these more likely to affect soil formation and structure, via expansion and contraction, effects on moisture content, freeze/thaw cycles and so forth?

Evolution and continental drift, I imagine.

Ask a rabbit breeder.

Yes, it's all a bit Dr Strangelove: "I'm not saying we wouldn't get our hair mussed. But I do say no more than 10-20 million killed, tops." (Buck Turgidson.)

As you can't be bothered to explain what the hell you are trying to do, or even to converse in complete sentences, I've now had enough of you.

No it isn't.

Depends what you are trying to do. If you just want to show what is bonded to what then it doesn’t matter, but if you want show spatial relationships then bond angles can become important.