Why do sparks occur only on a dry day?

[rootX]

Homework Statement

I think water prevents the sparks because it has a dipole thing. But I really do not know how sparks occur only on a dry day, like when you get charged and you touch some metal thing. And, I also want to know why electric sparks occur. From what I read, I think electrons move @ high speed from the source to the destination through air, and collide with air particles that cause sparks

Thanks a lot!

 

[Mentz114]

The kind of sparks made by static electricity require big charges to build up on cars, carpets, door handles and so on. On a damp day, the air is more conductive and the charge leaks away. If you had a spark machine, it would work on any day because it does not depend on chance the build up of static charge.