Lightning over SaddleBrooke Ranch (photo by Gerald Tietje)
Gerald Tietje
Lightning and thunder invoke both awe and fear in our imaginations; there is even a name for fear of lightning, astraphobia. That’s probably why the San Diego Chargers (now the Los Angeles Chargers) chose to have a lightning bolt on their helmets, even though lightning is seldom seen in that fair city. And why the country music festival held in Florence, Ariz., in April is called “Country Thunder.” These “bolts from the blue” and accompanying thunder are commonplace in SaddleBrooke Ranch during the monsoon season, which typically occurs sometime between June 15 and Sept. 15.
Lightning is a powerful force in nature. It involves an electromagnetic discharge that travels within a cloud (intra-cloud); from one cloud to another (cloud-to-cloud), or from a cloud to the earth (cloud-to-ground). The typical cloud formations that trigger lightning are cumulonimbus clouds, those large, puffy white clouds with ominous dark bottoms that reach heights of 14,000 to 17,000 feet over the Santa Catalina Mountains. Below-freezing temperatures at the tops of these clouds and strong updrafts within them that bring water and ice particles to the upper regions are prerequisites for lightning to occur. The process that causes the different parts of the clouds to become different polarities is complex, but when there is a sufficient polarity imbalance between regions within a cloud, between clouds, or between the cloud and the earth, a channel is created for electricity to flow. The most common cloud-to-ground lightning flash begins with electricity flowing downward to the ground in a barely visible channel (first stroke). This is followed by one or more upward strokes using the same channel; these are the bright flashes that we see.
Lightning causes rumbling thunder when the gasses in the vicinity of the electrostatic discharge experience a sudden increase in pressure, expanding outward from the lightning and creating an audible shock wave. Since light travels much faster in air than sound travels, we see lightning first and hear the resultant thunder later. How much later depends on how far the observer is from the lightning strike. When I was growing up, I was taught to count the number of seconds between the time when I saw the lightning flash and heard the thunder: 1001, 1002, 1003, etc. If I reached 1005, the lightning was approximately a mile from my location. Any closer, and it’s wise to take cover, as the old adage recommends, “When thunder roars, go indoors.”
Although dangerous, lighting is also fascinating. A website like www.lightningmaps.org shows all of the lightning strikes in the United States on a map in real time. Layers can be added to show rain, cloud cover, and other features, and it can be narrowed down to a specific area of the country, like SaddleBrooke Ranch. The monsoon season started later this year, but we have already seen many bolts from the blue, and thunder, too.