Oscillations of atmospheric neutrinos

The observation of muon flavor disappearance in the atmospheric neutrino flux provides compelling evidence for neutrino flavor oscillations and, by implication, for nonzero neutrino rest mass. We review recent results from Super-Kamiokande and other underground atmospheric neutrino experiments. These results, along with oscillation limits from reactor experiments, are evaluated in the context of neutrino three-state mixing. A unifying picture with v_μ to v_τ oscillation as the dominant mode emerges; however, certain ambiguities remain. Future directions for further experimentation are discussed.