Re: How do alkaline water spots form on windows in the Southwest?

The drops are most likely microdrops from the sprinkler system.  These 
microdrops can travel hyndreds of feet through the air.  Unlike regular 
drops, you will never feel them.  They will be sodium, potassium, and 
calcium carbonate containing depending on the hardness and alkalinity of 
the water.  To duplicate, just take hose water and put in a plant mister.  
Take a piece of glass and mist the air at a distance and probably above 
the glass.  You will need to trial and error the distances and the air 
flow where you are doing it.