Do clouds have to be in the sky for it to rain? Why do you add acid to water instead of water to acid?

Question: Do clouds have to be in the sky for it to rain? Why do you add acid to water instead of water to acid?
- Keywords:
  acid,
  clouds
Asked by thequestionmaker to Werner, Vicky, Nick, Madgie, Carla on 11 Nov 2013.
- Werner Muller answered on 11 Nov 2013:
  
  two questions in one
  part 1, for something to fall down it must be up in the sky
  part 2, you must not try to add water to acid. If you add water to acid, the temperature of the liquid will rise very quickly and it is really dangerous.

Question: Do clouds have to be in the sky for it to rain? Why do you add acid to water instead of water to acid?