1. Lightning and Thunder

2. Lightning http://www.youtube.com/watch?v=tKN_bJ0HXSs http://www.youtube.com/watch?v=6MUYsIjTKvk http://www.youtube.com/watch?v=jM8h60S1GsM

3. Stages of a Lightning Strike

4. Worldwide Distribution of Lightning

5. Speed of sound through Air 344 m/s Speed of Light through Air 300,000,000 m/s Which reaches you first? Lightning (waves) or thunder (sound waves) http://www.youtube.com/watch?v=hQix0b86LTU&feature=related http://www.youtube.com/watch?v=dKVFIBBwECU&feature=related

6. Thunder Lightning discharge heats the air (from 0° to 33,000° in a second!) The hot air expands – quickly, explosively. Lightning travels at the speed of light: 186,000 miles/sec Sound in air travels much slower: 1000 ft/sec So…. Thunder heard 5 seconds after lightning is seen = 5000 ft. (1 mile = 5280 ft)

7. Thunder more than 12 miles away is rarely heard due to reflection, refraction and absorption of sound by land features and buildings.

8. The speed of sound in dry air at 0°C is about 330 m/s. Water vapor (humidity) _________ the speed slightly Sound travels _______ through warm air than cold air Speed of Sound