Upward Lightning From Tall Objects
Upward lightning is initiated from a tall object and propagates upward to the overlying clouds. Cloud flashes and downward ground flashes begin with bipolar leader development. Upward lightning is unique in that it originates as an unipolar upward leader. In most cases, this upward leader is positively charged. It has been observed and studied since the 1930s, but there are still a number of unanswered questions regarding this phenomenon.
Below is an upward flash from a tower in Rapid City, SD captured with high-speed, high-definition, and standard-definition video cameras as well as digital still image cameras.
Digital still image
We can take the high-speed video and stack some of the individual video images to make a composite image showing the maximum brigthness value at each pixel location. Here is how that looks.
We can make a video of the progressive image stack technique showing how the flash develops. Saturatingly bright events are not added to the stack since they would wash out the rest of the image. They are allowed to play through however.