Why does peeling adhesive tape in the dark sometimes create a blue glow?

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energy levels of a luminescent centre — luminescence Figure 1: Energy levels of a luminescent centre (see text).

The phenomenon of a blue glow appearing when peeling adhesive tape in the dark is a form of triboluminescence.

This light is produced through the following process:

Charge Separation: As the adhesive tape is stripped from the roll, the mechanical separation of the surfaces generates positive and negative electric charges.1
Electric Discharge: These separated charges create an electric discharge in the immediate vicinity of the tape's surface.1
Light Emission: The discharge excites nitrogen molecules in the surrounding air, which then emit the characteristic blue light as they return to a lower energy state.1

This process is similar to other forms of triboluminescence, such as the sparkles seen when crushing sugar crystals, where mechanical energy is converted into light through the separation of charges.1