  Penrose's identification with warp provides the general framework for
constructing the continuous form of impulsive gravitational wave metrics. We
present the 2-component spinor formalism for the derivation of the full family
of impulsive spherical gravitational wave metrics which brings out the power in
identification with warp and leads to the simplest derivation of exact
solutions. These solutions of the Einstein vacuum field equations are obtained
by cutting Minkowski space into two pieces along a null cone and re-identifying
them with warp which is given by an arbitrary non-linear holomorphic
transformation. Using 2-component spinor techniques we construct a new metric
describing an impulsive spherical gravitational wave where the vertex of the
null cone lies on a world-line with constant acceleration.
