5. The Existence of Upward Lightning
Most people’s first image of lightning is bolts descending from the heavens to the ground. But there is an interesting and less well-known kind of lightning that really travels in the opposite direction—from the earth up towards the clouds. Ground-to—cloud lightning or upward lightning is the name given to this phenomena.
Usually starting from towering buildings like towers of communication, skyscrapers, or wind turbines, upward lightning comes from It happens when the electric field around the top of these constructions gets strong enough to start a leader travelling upward. The lightning channel is then completed by this leader connecting with opposite charges in the cloud above.
Though less frequent than conventional cloud-to- earth lightning, upward lightning is not infrequent. Actually, on really tall buildings, it can be the main form of lightning. Studies have indicated, for instance, that up to 90% of the lightning hits on wind turbines can be upward lightning.
For the protection of tall buildings, this kind of lightning presents special difficulties; moreover, it has significant effects on sectors such wind energy and telecommunications. Developing sensible lightning protection systems for very towering buildings depends on an awareness of upward lightning.