Thermal Fine Structure and Magnetic Fields in the Solar Atmosphere: Spicules and Fibrils

The relationship between observed structures in the solar atmosphere and the magnetic fields threading them is known only for the solar photosphere, even then imprecisely. We suggest that some of the fine structures in the more tenuous chromosphere and corona--specifically some populations of spicules and fibrils--correspond to warps in two-dimensional sheet-like structures, as an alternative to conventional interpretations in terms of tube-like structures. The sheets are perhaps related to magnetic tangential discontinuities, which Parker has argued arise naturally in low- Delta *b conditions. Some consequences of this suggestion, if it can be confirmed, are discussed.