dcc

When during a storm, the charge is developed in clouds, the high rise buildings are more prone to lightning strikes due to their lower potential as compared to ground with respect to the clouds thus lightning discharge falls on them. Now if they are not earthed, they discharge crrent in form of lightening to any other structure nearby having lower potential.

This called Lighting of conductor.

When same phenonmenon occurs in case of transmission lines or any other high current carrying power lines, it is called coronal discharge.