Dynamical correlation effects in the transition probability: A study for the atoms Li to Ar

► Explicitly correlated wave functions are employed to study atomic transitions. ► Different correlation mechanisms are analyzed for dipole transitions to the ground state for the atoms Li to Ar. ► The correlation factor improves the excitation energies. ► The correlation factor does not improve significantly transition probabilities, oscillator strength and line strengths. ► Configuration mixing is more important than the Jastrow factor for the transition probabilities.