Automobile ignition failure occurs in damp weather. Explain, why?

Explanation

The insulating porcelain of the spark plugs accumulates a film of dirt. The surface dirt is hygroscopic and picks up moisture from the air. Therefore, in humid weather, the insulating porcelain of the plugs becomes quasi-conductor This allows an appreciable proportion of the spark to leak across the surface of the plug instead of discharging across the gap.