How fast does a lightning bolt travel?

A lightning is usually produced by the cumulonimbus clouds in the atmosphere. In the clouds, negative and positive electric fields are formed from top to bottom containing negative and positive ions respectively. A column of ions (leader bolt) moves from the negatively charged part to the positively charged part, discharging electricity. The speed of such a bolt could exceed 22,000 kilometres per hour, that is 14,000 miles per hour, and can reach a temperature of more than 30,000-degree celsius.