  A dg manifold of amplitude +1 in $C^\infty$-context can be thought of as a
derived intersection of a section $s$ and the zero section of a vector bundle
$E$. In this paper, we compute the Atiyah class of dg manifolds of amplitude
$+1$. In particular, we prove that the Atiyah class of a dg manifold of
amplitude $+1$ vanishes if and only if the intersection of $s$ and the zero
section is a clean intersection. As an example, given two submanifolds $X$ and
$Y$ of $W$, we investigate the Atiyah class of a dg manifold which can be
thought of as a model for the derived intersection of $X$ and $Y$ in the sense
of Behrend--Liao--Xu.
