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your wrong and right. it can rise up from tall object thus creating the rumor or whatever that it comes from the ground. this is from yahoo answers
As negative charges collect at the base of the cloud, they repel the electrons near the ground's surface. This leaves the ground and the objects on it with a positive charge.
As the attraction between the cloud and the ground grows stronger, electrons shoot down from the cloud. The electrons move in a path that spreads in different directions - like a river delta. Each step is approximately 50 metres long and the branching path is called a stepped leader. Further electrons follow, making new branches. The average speed at which the stepped leader cuts through the air is about 270,000 miles per hour.
As the stepped leader approaches the ground, positive electrical sparks rise from tall objects such as trees and buildings. These sparks are known as upward streamers. When the stepped leader meets the upward streamer, the lightning channel is completed. When the lightning channel is complete, the electrons in the channel rush towards the ground. This is the return stroke which lights up the channel. The first electrons to reach the ground light up the bottom of the channel. The upper part of the channel glows as the electrons move rapidly down it. Therefore, the light from the flash starts at the ground and moves upwards. The branches of the stepped leader are also lit up, but not as brightly as the main channel as there are less electrons present. The lightning flash ends when there are no electrons left in the channel.
If lightning flickers, it is probably because there has been more than one return stroke. Following a lightning flash, the lightning channel is momentarily empty and it is then possible for electrons from another part of the cloud to enter it. The movement of the electrons into the channel is called a dart leader. It causes another return stroke to occur. The repeated return strokes and dart leaders make the lightning appear to flicker because of the great speed at which they occur.