physical phenomenon vs optical phenomenon

Other hyponyms of physical phenomenon include acoustic phenomenon, atmospheric phenomenon, boundary layer, chaos, cloud, decalescence, electrical phenomenon, electricity, energy, energy, free energy, power, event, field, field of force, force field, force, hysteresis, resonance, mechanical phenomenon, opacity, force per unit area, pressure, pressure level, reflection, reflexion, refraction, resolution, resolving power, resolution, conduction, conductivity, propagation, fundamental interaction, interaction, surface tension, syzygy, transparence, transparency, turbulence, turbulency, chop, floatation, flotation, adiabaticity.