At what voltage does the electric field become strong enough to ionize air?

The electric field strength necessary to ionize air is generally around 3 million volts per meter (or 3 kV/cm). When considering typical values associated with this phenomenon in practical scenarios, it is found that voltages around 13 kV are often cited as the threshold where the electric field becomes sufficiently strong to begin ionizing air. At this voltage level, the electric field can effectively strip electrons from air molecules, resulting in the creation of ions and free electrons, which can then lead to electrical discharges, such as sparks or corona discharge.

Thus, 13 kV serves as a crucial voltage level where ionization occurs, while lower voltages, such as 5 kV, 10 kV, or even 20 kV, might not consistently bring about ionization under typical atmospheric conditions. Therefore, it is this 13 kV mark that aligns most closely with the established threshold for air ionization.