Lightning And Thunder

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Lightning And Thunder

  1. 1. Lightning and Thunder<br />Paul Flynn<br />Picture from http://www.flickr.com/photos/dagpeak/13436814/ <br />
  2. 2. Contents<br />What is Lightning?<br />What causes it/how does it happen<br />Lightning Strokes<br />What is Thunder and what does it have to do with Lightning?<br />
  3. 3. What is Lightning?<br />Lightning “is similar to the electrical shock you have experienced on touching a metal object on a very dry day. Only the intensity is much bigger.” (Lutgens and Tarbuck pg. 296)<br />Part of the cloud becomes negatively charged, other part becomes positively charged.<br />Lightning acts to balances by creating positive or negative flows of current.<br />Most lighting is what is called “Sheet lightning” The other kind is called “cloud-to-ground lightning” and is much less frequent but much more dangerous.<br />
  4. 4. Sheet Lightning Cloud-to-Ground <br />http://www.flickr.com/photos/benjaminw/535722976/<br />http://www.flickr.com/photos/sminor/3399835774/<br />
  5. 5. Heat Lightning<br />Besides sheet and cloud-to-ground lighting, there is also a type that most people know as Heat Lightning. <br />This name is given to thunderstorms that are too far away for people to see or hear, so the result is a bright flash in the sky, which usually occurs when there is a warm humid night following a hot day. <br />
  6. 6. Heat Lightning<br />http://www.space.com/scienceastronomy/lightning_backgrounder.html<br />
  7. 7. What causes Lightning?<br />Rapid vertical movements inside Cumulonimbus.<br />5 Kilometer level, ice crystals develop.<br />Positive charge with colder regions.<br />Negative charge with warmer regions.<br />Small positive go up, Heavy negative toward base.<br />Surface has net positive charge.<br />Lightning stroke discharges negative region by striking ground.<br />
  8. 8. Lightning Strokes<br />Many very rapid strokes-Flash<br />Individual components-Stroke<br />Strokes begin when cloud releases electrons-Ionizing air<br />Path becomes known as leader<br />Electron flow increases electrical potential-more conductive, more ionizing<br />When close to ground, deposited electrons flow down<br />Return Stroke-electrons continuously extending up<br />As RS moves up, negative charge in channel is brought to ground<br />
  9. 9. Thunder<br />Discharge of lightning heats air<br />Air expands crazy! Produces sound waves<br />Possible to see lightning right away, not hear thunder<br />Happens along long lightning paths<br />Mountains and building delay sound<br />Lightning more than 20 km away has no thunder-Heat lightning<br />
  10. 10. Lightning/Thunder Facts<br />The total energy in a thunderstorm is more than that in an atomic bomb.<br />About 100 US residents are killed each year by lightning.<br />The Empire State building gets struck about 25 times per year.<br />Once lightning strikes, count seconds and divide by 5 (5 seconds =1 mile) <br />Thunder rumbles cause shock waves are created at different altitudes.<br />
  11. 11. What to do during a Thunderstorm<br />If in a forest, seek shelter in a low area under thick growth of trees.<br />If in an open area, go to low place like a ravine or valley.<br />If in open water, get to land and find shelter immediately.<br />
  12. 12. References<br />Britt, Robert Roy. "The Science of Lightning, Thunder and Thunderstorms." Space.com. 2007. Web. 28 Feb. 2010. <http://www.space.com/scienceastronomy/lightning_backgrounder.html>.<br />Lutgens, Frederick K., and Edward J. Tarbuck. The Atmosphere. 10th ed. New Jersey: Pearson Prentice Hall, 2007. Print.<br /> Heat Lightning. 2008. Photograph. Flickr.com, Tampa, Florida.<br />Lightning background. 2007. Photograph. Space.com.<br />P1121162. 2007. Photograph. Flickr.com. By Benjamin W.<br />Denver Lightning. 2004. Photograph. Flickr.com, Denver.<br />

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