Water (and other substances) can exist in many distinct solid phases (with different crystallic micro-structure), but only in two fluid phases – liquid and gaseous, in which the molecules are oriented randomly (they is no long range order). Is there an explanation in the molecular theory, why there are just two "disordered" phases? Why isn't there just one? Or more than two?
[Physics] Why does water ($\mathrm{H_2O}$) only have two distinct fluid phases
condensed-matterliquid-statephase-transitionstates-of-matterwater
Related Solutions
I'll make an attempt of partial answer here, and perhaps extend the question a bit : I think liquid water-gas water are already phases that spontaneously break symmetry of say your "water Hamiltonian". Since you can go continuously (without any phase transition) from one phase to the other phase (by going around the critical point at high temperature and pressure), these must have the same symmetry.
I think that a very related picture is to consider the ferromagnetic Ising model (which shares the same universality class as the water-gas critical point) but with a longitudinal field h that couples uniformly to z-spins. The Hamiltonian of this spin system is invariant under time-reversal symmetry.
If one has zero field, then we know that at a certain critical temperature ($T_c$), the spin-system (assume it's an infinite system) exhibits a spontaneous symmetry breaking - i.e. the system chooses an order parameter (local z-moment) that is not time reversal symmetrical - from a paramagnetic phase to a ferromagnetic phase (or vice-versa).
Now, if one turns on the longitudinal field ($h$), the Hamiltonian is no longer invariant under time-reversal symmetry, which means that even if you were to start from say the infinite temperature and finite h-field, as you lower your temperature, your system will never exhibit spontaneous symmetry breaking, since the h-field that you are applying already breaks time reversal symmetry. In other words, the positive and negative magnetization phases break time reversal symmetry, but do not break any symmetry of your Hamiltonian with finite h.
Hence, the phase with positive magnetization can be related to the phase with negative magnetization by going continuously around the critical point (as for water-gas !). Moreover, like water-gas transition, there is a line of first order transition that terminates at the critical point : this line for the Ising model is the h=0 line with $T<T_c$. If your are not going along that line, then you can never have a spontaneous symmetry breaking.
Therefore (and this is my point), the phase of your system that you want to look at and that has a different symmetry state must be along that line of first order transition (and is not the gas or water phases). In the case of the Ising model, it's just a ferromagnet breaking time-reversal symmetry of your Hamiltonian (h=0 line). However, for water I do not know how you characterize this phase. I guess a logical question to ask now would be : what does the Hamiltonian for the water looks like... And what are it's degrees of freedom. Then, one can answer your question about what symmetry is in fact broken.
Hope this helps a bit.
Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs 23% in deciduous trees. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings
It appears that wood is complex in its chemical state as it contains components of both liquid and solid form. Also when you burn wood many chemical reactions take place, primarily the converion of its carbon content to coke as well as production of $CO_2$, remember that it both goes in smoke and stays behind as ash, this is not a conventional phase transition as there is no clear phase change, it is much more of a chemical reaction with products in different state.
Best Answer
The most immediate answer would seem to be that a great variety of different crystal phases can exist because their long-range order makes it possible to classify them based on the different symmetries of their lattice structure. Since the liquid (or amorphous solid) phase only has short-range order and the gaseous phase doesn't even have that, it seems impossible for different fluid phases to exist.
However...
It turns out that it is possible for an amorphous substance (glass or liquid) to exist in different stable phases. This phenomenon, which is the amorphous counterpart of the polymorphism of crystal, is known as polyamorphism.
Quoting from Wikipedia:
One example is the liquid-liquid transition exhibited by some model systems, in which a transition from a low density to an high density liquid state appears.
The presence of a liquid-liquid critical point has been hypothesized to explain some thermodynamic anomalies of liquid water. Unfortunately, it is extremely difficult to reach this critical point experimentally, because the system undergoes spontaneous crystallization.
But it has been found out in numerical studies of some simple model systems of water that a liquid-liquid critical point is indeed present, and two distinct, stable liquid phases appear: a low density and high density liquid.
As far as gas are concerned, the absence of local structure (short-range order) makes it impossible for different phases to exist. The only exception which comes to my mind, if we want to call it a "gas", is the Bose-Einstein condensate, obtained when a dilute gas of bosons is brought to temperature close to absolute zero.
Updates
-Diffusive dynamics during the high-to-low density transition in amorphous ice (2017)
-Which way to low-density liquid water? (2017)
-Second critical point in two realistic models of water (2020)