High rise sky writing smoke jet printer

Sky writing is pretty cool. I've never understood how the pilot manages to join up his 'o's - or how he knows where to start the next letter.

My idea will obviate the needs for specially trained (and expensive) pilots. It works sort of like an ink jet printer. Except instead of ink being shot on to a page of paper it shoots smoke up in to the air. The print head is mounted on top of a high rise building, and instead of the print head moving it relies on wind to move the 'paper' to the side.

Of course, you'd have to measure the wind speed and print faster on blustery days. On calm days you might just get a message that reads 'mmmfff'. Someone would have to come up with glow in the dark smoke for night times, and water proof smoke for rainy days. Coloured smoke would help on overcast days too.