Upward lightning discharges: An update

Lightning discharges initiated by leaders that originate from stationary grounded objects, usually towers, and propagate upward, toward overhead thunderclouds, are reviewed. Upward, or object-initiated, lightning discharges always involve an initial stage that may or may not be followed by downward-leader/upward-return-stroke sequences. The initial-stage current often exhibits superimposed pulses whose peaks range from tens of amperes to several kiloamperes (occasionally a few tens of kiloamperes).