My question is motivated by phenomena on the Sun. The Sun’s outer atmosphere, the corona, is  about 1 – 2 million Kelvin. But the surface of the Sun is only 5800 K. One strong theory regarding coronal heating proposes that sound waves on the Sun, created by convection cells under the surface, propagate out into the solar corona and transform into magnetic waves. This transformation occurs at a point where the pressure of the gas in the atmosphere and the pressure of the magnetic field of the Sun are about equal, ß ~ 1. This transformation allows for energy to be carried a little further into the corona where the energy is deposited as heat (Johnson, et al., 2002; Bogdan, et al., 2003).

Image from Universe, 6th ed., 2002

Sources:

Bogdan, T.J., et al. “Waves in the Magnetized Solar Atmosphere. II. Waves from Localized Sources in Magnetic Flux Concentrations.” Astrophys. J., 599, 626-660, 2003

Freedman, R.A. and W.J. Kaufman III. Universe (6th ed.). W.H. Freeman & Co., 2002

Johnson, M.C., S. Petty-Powell, and E.J. Zita. “Energy Transport by MHD Waves Above the Photosphere Numerical Simulations.” 17 Oct 2002, website

Next: What is ß?

 

How are aurorae created?
Can we hear the aurorae?
Wave transformation on the Sun
What is ß?
How can a magnetic wave transform into an acoustic wave?
Does ß=1 anywhere in Earth’s atmosphere?
Continuing research
Bibliography