A3  

Lightning and Thunder

           DEFINE LIGHTNING 

Lightning is the large electrical discharge that occurs between two oppositely charged areas.

DEFINE THUNDER

Thunder is the sound that results from the rapid expansion of air along a lightning strike.

How Lightning is created

Updrafts and downdrafts (convection currents) move ice crystals and water droplets through a cloud, their movement creates posotive and negative charges.

STEP 1

A moving thunderstorm gathers another pool of positively charged particles along the ground that travel with the storm. this is why sometimes, if you stand outside in a lightning storm, your hair stands on end.

A channel of negative charge, called a "stepped leader" will descend from the bottom of the storm toward the ground

Once the step leader's channel is complete, the circut will close and the positively charged electrons from the ground run to the negative charged ones and back. We call the electricity in this situation lightning. The example shown is called cloud to ground lightning. If the step leader forms from the negative and positive charges in the cloud, lightning occurs within the cloud, which is called cloud to cloud lightning.

THUNDERHow it is created: • Lightning is extremely hot (up to 54,000ºF). 

 • The heat causes the air to quickly expand

and contract faster than the speed of sound (768 mph). 

 • This creates the sound waves we hear as

thunder. • Sound is created when the air vibrates - the

air vibrates your eardrum and you hear sound.  The rapidly expanding air causes the air to vibrate and produce sound.

Thunder

Does lightning travel faster than thunder? Yes, lightning is light and light travels to the eye at a speed of 299,792,458 metres per second while thunder is sound and travels to the ear at a speed of 344 metres per second.

sound

light

What Cloud Type Creates Lightining and Thunder? The cumulonimbus cloud is the cloud that creates lightning and thunder. Low air pressure creates this cloud!

The Risks...

- You can get shocked - Electrocution- Forest fires

- Injuries can occur if someone is struck by lightning or if an object is struck by lightning and it falls on someone.

Fun Facts about Lightning and Thunder!- Lightning often strikes outside of heavy rain.

- A flash of lightning is no more than one inch wide. - Lightning has "favorite" sides that it may hit many times in one storm.- In one place there may be 4 different strokes which makes lightning appear to flicker.