  We introduce a description of Ramsey spectra under atomic interactions as a
sum of decomposed components with differing dependence on interaction
parameters. This description enables intuitive understanding of the loss of
contrast and asymmetry of Ramsey spectra. We derive a quantitative relationship
between the asymmetry and atomic interaction parameters, which enables their
characterization without changing atom density. The model is confirmed through
experiments with a Yb optical lattice clock.
