+ CG Positive cloud to ground strike
- CG Negative cloud to ground strike
+ IC Positive in cloud or intracloud strike
- IC Negative in cloud or intracloud strike

Cloud to ground lightning
Cloud-to-ground lightning is the most damaging and dangerous form of lightning. It is not the most common type, but it is the one that is best understood. Most cloud-to-ground lightning strikes come from the negatively charged bottom of the cloud traveling to the positively charged ground below. Some cloud-to-ground lightning strikes deliver positive charges to the ground. Positive strikes are less common and come from the higher regions of the thundercloud.

Often, cloud-to-ground lightning bolts strike the highest object, like the top of a building or the top of a tall tree. The lightning strikes can cause fire and property damage. If a person is the highest object in the lightning bolt's path, the lightning may strike the person. Lightning strikes can cause severe injury or death. Cloud-to-ground lightning is the best understood type of lightning because it leaves so much evidence behind.

In cloud lightning
In cloud lightning is the most common type of lightning. This occurs between oppositely charged centers within the same cloud. This means that there are both positive and negative charges within the same cloud. Usually the process takes place within the cloud and looks like a bright flash of light which flickers. This bright flash may leave the cloud and the flash can be visible for many miles.

Intercloud lightning
A less common lightning strike occurs between oppositely charged areas of different clouds. This means that there are positive and negative charges within different clouds and the strike travels in the air between them. This type of lightning is known as intercloud lightning.