## Curious phase transition

Do you think earth can be considered as some kind of solid gaz, or at least as complex system, in order to study it trough a thermal/energetical point of view? Is it what you call an extensive study?

Why would'nt it be interesting? Such a method would save obviously a lot of calculus and measures in order to describe few characterisics of any planet.

 Quote by flicflex Such a method would save obviously a lot of calculus and measures in order to describe few characterisics of any planet.
No.

Mass & radius of a planet are in a way random and depend on the initial conditions in the system from which the planet emerged. They are easy to measure and they are the basic input data used to build the planet model. You can't use other data to predict mass & radius, as you don't have the other data.

 Quote by flicflex solid gaz,
This is an oxymoron.

Recognitions:
 Quote by flicflex But why does the materia doesn't accumulate anymore (isn't solid anymore) beyond that greatest gravitational potential field (6400km)?
Mateiral is still accumulating, at a rate of about 10,000 to 20,000 tons per year. http://en.wikipedia.org/wiki/Micrometeoroid

 Quote by Borek No. Mass & radius of a planet are in a way random and depend on the initial conditions in the system from which the planet emerged. They are easy to measure and they are the basic input data used to build the planet model. You can't use other data to predict mass & radius, as you don't have the other data.
They are not independent.

You cannot predict mass from radius without knowing composition. With mass and composition you can predict radius - reasonably easy at intermediate masses, gets harder at low and high masses. The radius does depend on internal heat (slightly).

Now, as for "phase change"...

The surface of ground is NOT generally at 0 altitude. The surface of water is.

When you look at water surface, you commonly see two, and even three transitions, depending on weather.

Counting from up to down, you will find mostly gaseous air, then mostly solid water, then mostly liquid water, then mostly solid rock.

The smallest composition contrast is the one between mostly solid water and mostly liquid water.

But before you single that out as a phase transition in contrast to the other two transitions, note that the liquid water contains significant amounts of liquid (dissolved) rock, which is missing in solid water, and smaller but also significant amounts of liquid (likewise dissolved) air.

The mostly gaseous air above contains significant amounts of gaseous water. And the mostly solid rock contains significant amounts of liquid water, as well as liquid (dissolved) rock and liquid (dissolved) air.