The Comb Experiment, Kilometres Tall
- Two things move past each other: droplets falling, warm air rising
- Friction between them exchanges electrons, exactly as in a comb and hair
- No storm means no movement, no friction and no lightning
- Nothing new here at all. Only the size has changed
Presenter notes: Begin by holding up the comb from two lessons ago and running it through your hair. Ask what it is doing. Rubbing, moving electrons, making one thing negative and one thing positive. Then say the sentence the whole lesson rests on: that is lightning. Exactly that, with nothing added, except that the comb is now a cloud several kilometres tall. Let them object. Somebody will say lightning is far more powerful, and they are right, and that is the only difference. Same physics, enormously bigger, and the size is what turns a harmless crackle into something that kills around eighty people in Nepal every year.