Due to the optical effects caused by atmospheric discharge, lightning strike was called by various names among the people. If the discharge is visible to our eye as a line that branches close to the ground we call it "the line lightning" and if there are more such lines we call it "ribbon lightning". Sometimes we see the discharge in form of small glowing balls that follow one another. We call that "the pearl lightning", and if the balls are bigger with longer tail then we have so called "ball lightning". Sometimes we don't hear thunder, and all we can see is light. That kind of lightning we call "the blitz lightning" or "luster of time". Sometimes it will get other way around, we don't see anything, but we hear the thunder. That is so called "dark lightning". Light of lightning strike sometimes seams to be "flickering". That happens when several lightning strikes pass through same channel in a very short time.
Today, when physical characteristics of lightning are more or less researched, we can say that its effects are actually a radiation of hot plasma (about 3000 deg. C). The optical effects of atmospheric discharge, which human eye can see, can lead us to wrong conclusions about path of lightning and about its real dimensions. Development of photography enabled us to find out more about that. By taking pictures of lightning we found out that its light radius is 5 - 30 cm depending on which film and exposure we had, and the current of lightning is concentrated in 1 mm diameter, as was concluded in laboratory researches.