Summit County’s shocking skies: A lightning primer
Special to the Daily
Lightning has thrilled, awed and terrified people since the days of our ancestors. Some Native American tribes thought it originated with the flight of a mythical “thunderbird,” which flashed lightning from its eyes and spawned rolls of thunder with its enormous wings. The Norse god Thor was said to ride through the heavens on a chariot pulled by thunderous goats, casting lightning strikes with his giant hammer.
The modern story of lightning begins with the water cycle. As sunlight warms and evaporates surface water, the resulting vapor rises into the atmosphere where the air is much cooler. The water vapor loses heat to the surrounding air, and eventually condenses into small liquid droplets around small particles of dust floating in the air. Multiply these droplets by a few trillion and you get a cloud. In some cases, the cloud actually gets an electrical charge, kind of like a battery. Scientists still aren’t 100 percent sure about why this happens. Many speculate it’s a result of the small particles of vapor and water droplets colliding and knocking off electrons. This results in positive-charged particles rising to the top of a cloud, while negative charges stay at the bottom. Freezing temperatures at the top of the cloud amplifies this separation, and as time goes on, the cloud becomes an intensely charged electrical field, the strength of which continues to build until electrons on the ground are repelled away from the cloud bottom. This means the surface of Earth below the cloud becomes positively charged. The air between the Earth and the cloud begins to break down, creating pathways in the atmosphere for the electricity to flow called “step leaders.” Objects on the ground respond to the electrical field by putting out “positive streamers” toward the sky. When a step leader from the cloud reaches a positive streamer from the ground, a short-circuit path is formed for the cloud to discharge. And there you have it – instant lightning!
So much electricity is discharged in a lightning strike that the surrounding air reaches temperatures between 30,000F and 55,000F – about three or four times the temperature at the surface of our sun! The superheated air is actually the “flash” of light we see in a lightning strike. The heat expands the air so quickly that it literally explodes, sending out a shock wave we detect far away as thunder.
When you’re out enjoying any of the countless trails here in Summit County and a thunderstorm happens to roll in, there are several things you can do to reduce your risk of getting in the path of a lightning strike:
1. Prevention. In the summertime, mountainous regions like Summit County are infamous for mid-late afternoon thunderstorms. Check weather predictions and consider starting your trek early to minimize possible exposure.
2. Prediction. Thunder travels about 1 mile in just under 5 seconds. Counting the time difference between flash and bang can help indicate the distance away from you. Generally speaking, when a storm rolls within 6 miles (30 seconds between flash and thunder), it’s time to find safe shelter.
3. Protection. Put yourself in a safe place with respect to the terrain. Peaks and ridges are not great places to be if you suspect a lightning strike, nor is on/near standing water. Look for dry ravines or a low spot in rolling hills. If you are in a forest with trees of the same size, you’re generally safer than near trees out in the open, but you should avoid hunkering down right next to a tree.
4. Position. If you do get caught out in the open, crouch on something that provides insulation between you and the ground (like a foam sleeping pad). If you are traveling with a group, its best to spread out a bit from the others if possible. This helps ensure that if there is an injury from a lightning strike, there will be others who can respond.
5. Patience. Lightning can still strike well after a storm has rolled through, so it’s a good idea to wait about 30 minutes after the last flash-bang before assuming you’re safe to move again.
Daniel Rudolf is the assistant camp director at Keystone Science School. He can be reached at firstname.lastname@example.org. Visit our website, http://www.keystonescienceschool.org or call us (970) 468-2098 for information on our program offerings.
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