Science Sundays: What is "Dry Lightning"?

** FILE **Lightning strikes in the high desert north of Phoenix, Ariz., near the community of Crown King seen in this Thursday, June 29, 2006, file photo. Fears of a catastrophic fire season in Arizona have greatly eased with the arrival of seasonal monsoon rains, which began on schedule in the past week. A winter-long drought that gripped the state had fire managers issuing dire warnings in late spring that tinder-dry forests across the state were primed for huge wildland fires. Several large fires did erupt, but none of the massive size feared. (AP Photo/Tom Hood)