Variance spectra were generated for three high-frequency near-surface soil temperature time series representative of soil conditions typically encountered in temperate regions: saturation, strong evaporation, and soil frost penetration. For the latter two conditions, a surrogate measure of the soil water ionic concentration was also obtained and variance spectra were calculated. In a purely conductive system of multiday duration, maximum thermal variance should occur at a wavelength of 1 day and should decrease with depth. During ground saturation, when the pores are occupied by water, this pattern is observed. However, a spectral power density peak is observed in the subdiurnal and subhourly range coincident with surface evaporation or freezing. In addition, the ionic concentration of soil water at depth is strongly coupled to temperature variations at the surface. These patterns are atypical of conductive systems and suggest the operation of nonconductive heat transfer processes, particularly water advection, phase transformations of water, and high-velocity internal distillation. ¿ American Geophysical Union 1993