  A photonic jet commonly denotes the specific spatially localized region in
the near-field forward scattering of a light wave at a dielectric micron-sized
particle. We present the detailed calculations of the transient response of an
airborne silica microsphere illuminated by a femtosecond laser pulse. The
spatial area constituting the photonic jet is theoretically investigated and
the temporal dynamics of jet dimensions as well as of jet peak intensity is
analyzed. The role of morphology-dependent resonances in jet formation is
highlighted. The evolution scenario of a nonstationary photonic jet generally
consists of the non-resonant and resonant temporal phases. In every phase, the
photonic jet can change its spatial form and intensity.
