Why is it that ozone can be smelt after a thunderstorm?
In a thunderstorm, the discharge of the lightning occurs at INSANELY high voltages. Because of these high voltages, chemical reactions that normally wouldn't occur now do. Elemental nitrogen and oxygen combine and when a lightning bolt goes off various amounts of NOx's and ozone is created. Ozone is created by the following reaction:
3O
2(g) + Energy => 2O
3(g)
For the reaction to proceed, a great deal of energy needs to be put into the system and the lighntning bolt provides such energy. The same thing is noticed around electrical equipment that is short circuiting. The short circuit creates a voltage discharge that allows ozone to form. Since ozone has such an intensely pungent odor, you're able to smell the tiny bits that are created.