BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: Lightning

An Electrifying Tragedy: The Death of Two Giraffes

On March 2nd, two giraffes were found dead after a thunderstorm in Rockwood, which is a private nature reserve to the west of Kimberely, South Africa. The elder, a five year old female, had a fractured skull as well as a broken ossicone (knoblike horns). These injuries indicate she had died after a direct lightning strike to the head. The second giraffe, a four year old female, was found dead  about 23 feet away from the first giraffe. There are no visible injuries on the second giraffe.

According to Ciska P.J. Scheijen, a student in the Department of Animal, Wildlife, and Grassland Sciences, wrote a paper describing the event. In the African Journal of Ecology, Scheijen describes four ways lightning can kill an animal. It can strike the animal directly, as seen in the older giraffe. It can hit as a “side flash”, which is when the lightning arches into the animal’s body after striking a nearby object. It can also kill through “touch potential” (when the animal is in contact with a lightning-struck object) or “step potential” (when the animal is in contact with lightning-struck ground). It can be inferred that the second giraffe either died from a side flash or step potential.

The giraffes were in an area without trees, making them the tallest things in the area. Knowing this, I bet you and I are wondering the same question. Yes, “Do giraffes get struck by lightning more often than other animals?” The question we all need answered!

There have been a few incidents of giraffes dying of lightning strikes, including one at Disney World’s Animal Kingdom. However, there aren’t any real concrete numbers to determine a conclusion.

Yet, Universiti Putra Malaysia electrical engineer Chandima Gones wrote a paper on animal lightning strikes. He states that “animals with a large separation between their front and back feet…are vulnerable to receive lightning injuries due to the dangerous potential differences that may built up between these feet…” Gomes also writes how taller animals (lik giraffes) are more likely to be victims of side flashes and touch potential if near a lightning struck tree. Without clear cut numbers, though, it’s hard to be sure if giraffes are struck at higher rates than other animals.

But there’s another factor involved in the deaths of the two giraffes back in March that is important. There was a thunderstorm. It was raining.

Water is a covalently bonded molecule containing two hydrogen atoms and one oxygen atom. It is a polar molecule because oxygen is more electronegative than hydrogen. Water has many cool properties. For example, it has an unusually high specific heat, making it harder to change its temperature. Because of this specific heat, it allows living creatures that are largely made of water (like us) to resist drastic changes in the body. Water keeps us alive.

Water is an extremely important molecule for life, including our own. However, when electrocuted, it could very well kill us. We all know we shouldn’t swim in a thunderstorm, but did you know wet skin has 100 times less resistance than dry? That’s right: the amount of water in the body is a huge factor in whether or not you would survive an electrical shock.

Of course, the giraffes didn’t know this. They couldn’t find shelter during the thunderstorm that ultimately led to their own demise. While we may never know if giraffes are more susceptible to electrical shocks by lightning, we do know it’s wise not to mix water and electricity.

Lightning Expected to Increase by 50 Percent with Global Warming

Thunderstorm_over_Corfu

University of California Berkley scientist David Romps and his colleagues analyzed 11 different climate studies and concluded that changing climate will include increased lightning strikes. The studies, focusing on cloud buoyancy and precipitation, showed an increased amount of water vapor due to warming air. Water vapor is the fuel for for thunderstorms and explosive deep convection in the atmosphere, and with increased amounts in the atmosphere the frequency and ferocity of these storms will increase. Precipitation-the total amount of water hitting the ground in the form of rain, snow, hail, sleet, etc.- is essentially a measure of how conductive the atmosphere is.  Buoyancy is measured in the form of CAPE, convective available potential energy. This measures how potentially explosive the atmosphere is. Romps found that by analyzing these two factors he could accurately predict strength, frequency, and size of storms.

Article Link: http://www.sciencedaily.com/releases/2014/11/141113142112.htm

Useful Links:

http://en.wikipedia.org/wiki/Thunderstorm

http://en.wikipedia.org/wiki/Convective_available_potential_energy

Image Link:

http://commons.wikimedia.org/wiki/File:Thunderstorm_over_Corfu.jpg

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