The electric strength of air

Air is the commonest and most widely used of insulators. Its insulating characteristics are remarkably good; it has low specific inductive capacity, very low conductivity, and an electric strength or resistance to rupture which until recently has met all the demands of the electrical engineer. As a result of the increase in values of transmission voltage, however, and of improvements in high-voltage apparatus and line insulators, the electric strength of air has become a limiting factor in the long distance transmission of power.