Atmospheric dynamics are often conspicuously Non-Newtonian, with complex quasi-oobleck Deborah Number rheology. Being substantially Phonon-based, Sonic Relativity is a significant aspect.
Consider Power Kites in this context. A wind tunnel or water flume can be regarded as a hydrodynamic phonon Quasiparticle Accelerator. Natural Wind is analogous to Cosmic Rays, as a ubiquitous research particle source. A toy kite is therefore a workable experimental physics apparatus anyone can get their hands on. As a rather unique phase of condensed matter, it can be called "Kitematter".
A kite interacts with wind flow in complex ways. Its a dissipative system, a thermodynamic "heat engine" with hot (bottom) and cold (top) fields. The complex far field is in fact determining, and the kite itself is just a small topological defect in it. The kite's wake is a complex train of phonon debris, of shed vortices analogous to the particle wreckage particle accelerators like CERN create. Each step of the way, the phonon creation and annihilation sequence can be Feynman Diagrammed. The key phonon sequence of "green" interest is along the kite line.
Kite line hums with internal phonons as it sheds its own wake. When line is tense, sonic c can range beyond 50km/sec. Fly a kite high, sight along the line, and pluck it to see a pulse traveling faster than c in air. When the line is nearly slack, see waves moving less than 30m/sec. This is how easily sonic relativity is observed. Kite Control and Stability derivatives are highly dependent on sonic relativity.
Fly a kite high, sight along the line to sample wind field turbulence, seen as various bumps coming and going. Typically, there will be a bulk hodographic twist to kite orientation, known as an Ekmann Spiral, a Coriolis Effect.
In smooth minimal wind, a kite can seem "pasted to the sky", its zero-point energy level. Close observation reveals minute "dancing" oscillations in six dimensions (3 angular and 3 translational). With more wind, the kite begins to dance more energetically, and these free-energy sweeping motions can be harvested. Yaw and roll combine in a characteristic Lissajous lemniscate path, circular symmetry broken by gravity, the well known figure-of-eight (Dutch Roll), the most energetic dimensions.
Passive cybernetic embodied "edge-of-chaos" Control Theory explaining inherent emergent kite motions is conceptually advanced. Energy and control sensing-actuation information superposes and flows both ways. A kite can sustain flight in calm by pumping input from the ground. Spoiler-alert: Kite Network Topological Stability is optimal. Active Digital Control is best relegated to exception-handling.
Obviously kites are first class mathematical physics teaching aids. Its no coincidence that so many historical mathematical physicists have had close association with kites, and the science continues to unfold [Physics World, Feb, 2020].
What concerns us here is not just analytical kite curiosities as such, but the practical fact that the vast kinetic energy of upper wind may transfer by power kite networks to the ground, as towing force on kite lines, and how this force can turn the largest generator shafts. This may be the most important applied ("green") Mathematical Physics Azimuth Forum has considered.