can someone explain this to me please…
left work, no ice around anywhere, got to car and condensation on the windscreen + bodywork (not ice). I got in the car and turned engine on, outside temp said 1.5 degrees, then i wiped the screen to remove the condensation… all ok so far. I then noticed a couple of smears on the screen so i used the washers for a tiny blast and the screen wiped. But then ice started forming on the screen, spreading out from various points. It was a bit like when you press the disc on a handwarmer pack, the ice just spread out slowly until most of the screen was covered. It was a very thin layer as i could see crystal patterns forming. Anyway i left it until it melted from the heat from the blowers and then drove off.
So….
Why did ice form when there was no ice (just condensation on the screen initially?
Why did ice form when it wasn't even freezing (temp remained 1-1.5 all the way home)?
and why did the ice form after i'd cleared the screen with my screenwash at -20 dilution (i used it neat when i filled it after the recent cold spell when it was -13 up here)? I normaly dilute it with water but was definately filled with neat stuff this time.
Is it because the alcohol in the screenwash evaporated and cooled the screen further then water vapour in the air froze on the supercooled screen? And if so why doesnt this happen when driving?
Anyway, it was quite impressive watching the whole screen cover in a layer of ice, especailly as it spread out from lots of little points which then all joined up. Very pretty seeing all the crystals growing.