IL NUOVO CIMENTO VOL. 79 B, N. 2 11 Febbraio 1984 Propagation of a Strong Hydromagnetic Cylindrical Shock in a Rotating Gas ('). S. KL-MA~ and R. PRAKASH Physics Depavfment, Agra College - Agra-282002, India rieevuto il 16 Scttembre 1983) S-mmary. -- The Chisnell-Chester-Whitham method has been used to study the propagation of a strong diverging cylindrical shockin arotating gas in the presence of a magnetic field having only constant axial and azimuthal components. By assuming an initial density distribution law as qo = Q' rw, where Q' is the density at the axis of symmetry and w (= wl -- w2, where wt is a constant due to the rotation of the gas and wt due to the azimuthal component of the magnetic field) is a constant, an analytical relation for the shock velocity has been obtained. The expressions for the radial particle velocity and the pressure immediately behind the shock have been obtained. PACS. 52.30. - Plasma flow; magaetohydrodynamics. l. - Introduction. The propag,~tion of a cylindrical hydromagnetic shock in a rotating gas is re- levant to the study of thunder. The CCW (1-,) method is used to investigate the propagation of a strong diverging cylindrical shock through a rotating gas in the (*) To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. (1) R. F. CHISNELL: Prec. ~. See. Zondon, Set. A, 232, 350 (1955). (2) W. CH~:S'r~R: Philos. Mag., 45, 293 (1954). (a) G. B. ~VmTm~: J. Fluid .Mech., 4, 337 (1958). 224