article_snippet.sent: And there are roughly five to 10 times as many cloud flashes as there are cloud-to-ground flashes.
article_snippet.sent: Within these strikes are two types of ground flashes known as natural and triggered.
article_snippet.sent: The latter includes strikes to very tall structures, planes, rockets and towers and goes from the ground up to the cloud.
article_snippet.sent: The map above shows the average yearly counts of lightning flashes per square kilometer from 1995 to 2013.
article_snippet.sent: Areas with the fewest number of flashes each year are grey and purple; areas with the largest number of lightning flashes - as many as 150 per year per square kilometer (0.4 square miles) - are bright pink.