How thick is a lighting bolt?
In a large rain cloud, as water droplets bump into each other and increase in size, they become electrically charged. This activity causes electric charges on the ground, too. Sometimes the charges increase until they become so strong (up to 200 million volts!) that electricity runs through the air between the cloud and the ground in the form of a giant spark or lightning bolt. The diameter of a lightning bolt is about a 0.5 to 1 inch (1.3 to 2.5 centimeters) wide, but can be up to 5 inches (12.7 centimeters) wide. The average length of a lightning bolt from a cloud to the ground is 3 to 4 miles (4.8 to 6.4 kilometers) long. Lightning can occur not only in thunderstorms, but also in snowstorms, sand storms, and above erupting volcanoes.