How RC circuit (spark quencher) works in AC network

I understand the operation of Fly Back diode in a DC in circuit that it minimizes the arcing between relay contact if a coil is connected to the relay contact, but I could not understand that how an RC (spark quencher) in AC network minimizes the arcing between relay contact. RC circuit is a conjunction of resistance and capacitor. When relay contact opens, a high voltage generates in output coil, how the capacitor SAVE that high voltage in a very short time while there is also a resistance in series with capacitor.