Why is this a flash circuit?

When the flash is turned off, it can be considered as an open circuit (high resistance). At this time, the capacitor is slowly charged through the resistor, and the capacitor voltage rises. When the capacitor voltage is higher than the flasher breakdown voltage u, the flasher will be turned on immediately. At this time, the flash will generate a relatively large current, and the voltage through the resistor will increase. At this time, the capacitor will discharge the flash lamp, and after the flash lamp is turned on for a period of time, the capacitor voltage will be lower than the flash lamp breakdown voltage. At this point, the flash will turn off and the capacitor will turn off again.