The propagation of flexural waves in floating ice plates is governed by two restoring forces – elastic bending of the plate, and the tendency of gravity to make the upper surface of the supporting water horizontal. This paper studies steady wave patterns generated by a steadily moving source on a water–ice system that is assumed to be homogeneous and of infinite horizontal extent, using asymptotic Fourier analysis to give a simple description of the wave pattern far from the source. Short-wavelength elastic waves propagate ahead, while the long gravity waves appear behind; and, depending on the system parameters, one, two or no caustics may appear. Wavecrest patterns are shown, and the amplitude variation with direction from the source is given. Where the two caustics just merge together, a special mathematical function analogous to the Airy function is introduced to describe wave amplitudes. These waves can be detected by a strainmeter embedded in the ice, and we compare its theoretical response with some experimental measurements.

The role of heat flux limitation in soft X-ray emitting solar flare plasmas is considered. Simple analytic arguments suggest that flux limitation is likely to be important during the explosive heating phase, even for relatively modest coronal energy fluxes (say < 109 erg cm-2 s -1). This conclusion is reinforced by a detailed flare loop simulation of the heating phase. Since flux saturation effectively 'bottles up' the coronal heat flux, mass motions now assume a dominant role in transferring energy from the coronal flare source to the lower transition region. The mass-energy exchange between the corona and chromosphere produces dramatic changes in the thermal structure of the plasma which are reflected in the differential emission measure profile of the flaring loop.