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The high-speed solar wind streaming from the southern coronal hole was remarkably uniform and steady and was confined by a sharp boundary that extended to the corona and chromosphere. Charge state measurements indicate that the electron temperature in this coronal hole reached a maximum of about 1.5 million kelvin within 3 solar radii of the sun. This result, combined with the observed lack of depletion of heavy elements, suggests that an additional source of momentum is required to accelerate the polar wind.

Formulas are derived for the amplitudes of waves that diverge from a shock as a result of any given incident disturbance. For strong shocks, that is the Mach number (M) is large, in an ideal gas it is shown that the pressure amplitude and the component of the energy flux normal to the shock of a transmitted sound wave are of O (M2 greater than those in the incident sound wave. Furthermore, if the impinging sound wave is incident near the critical angle the ratio of the pressure amplitude of the transmitted sound wave to that of the incident one is of O (M3). On the other hand, if a sound wave is normally incident upon the back of the shock, only about 1% of the acoustic energy flux is reflected in the form of sound waves. It is also shown that incident entropy-vorticity waves can generate intense sound waves behind a strong shock. The dependence of the transmission, reflection, and generation coefficients for sound waves on the Mach number and the angle of incidence is depicted in a series of graphs. The results are applied to the amplification of small disturbances in the solar wind on passage through the bow shock of the earth.

In this paper advected invariants and conservation laws in ideal magnetohydrodynamics (MHD) and gas dynamics are obtained using Lie dragging techniques. There are different classes of invariants that are advected or Lie dragged with the flow. Simple examples are the advection of the entropy S (a 0-form), and the conservation of magnetic flux (an invariant 2-form advected with the flow). The magnetic flux conservation law is equivalent to Faraday's equation. The gauge condition for the magnetic helicity to be advected with the flow is determined. Different variants of the helicity in ideal fluid dynamics and MHD including: fluid helicity, cross helicity and magnetic helicity are investigated. The fluid helicity conservation law and the cross helcity conservation law in MHD are derived for the case of a barotropic gas. If the magnetic field lies in the constant entropy surface, then the gas pressure can depend on both the entropy and the density. In these cases the conservation laws are local conservation laws. For non-barotropic gases, we obtain nonlocal conservation laws for fluid helicity and cross helicity by using Clebsch variables. These nonlocal conservation laws are the main new results of the paper. Ertel's theorem and potential vorticity, the Hollman invariant, and the Godbillon Vey invariant for special flows for which the magnetic helicity is zero are also discussed.PACS numbers: 95.30.Qd,47.35.Tv,52.30.Cv,45.20Jj,96.60.j,96.60.Vg