EDP Sciences
Free access
Volume 370, Number 3, May II 2001
Page(s) 1088 - 1091
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20010278

A&A 370, 1088-1091 (2001)
DOI: 10.1051/0004-6361:20010278

Acoustic waves in a stratified atmosphere

III. Temperature inhomogeneities
G. Bodo1, W. Kalkofen2, S. Massaglia3 and P. Rossi1

1  Osservatorio Astronomico di Torino, Strada dell'Osservatorio 20, 10025 Pino Torinese, Italy
    e-mail: rossi@to.astro.it
2  Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
    e-mail: wolf@cfa.harvard.edu
3  Dipartimento di Fisica Generale dell'Università, Via Pietro Giuria 1, 10125 Torino, Italy
    e-mail: massaglia@ph.unito.it

(Received 3 December 1999 / Accepted 15 February 2001)

In a gravitationally stratified atmosphere, small temperature variations distort the paths of acoustic waves from the rectilinear paths in an isothermal atmosphere. For temperature increasing upward, low-frequency waves near the acoustic cutoff frequency propagating at a given polar angle are refracted towards the vertical direction (focused) and high-frequency waves, away from the vertical (defocused). Similarly, for temperature increasing towards the axis of a vertical cylinder, low-frequency waves are focused and high-frequency waves are defocused. This effect of temperature inhomogeneities may be important for wave propagation in the chromospheric K$_{\rm 2v}$ bright point phenomenon.

Key words: hydrodynamics -- Sun: chromosphere -- waves

Offprint request: G. Bodo, bodo@to.astro.it

© ESO 2001