Naked Science Forum

General Science => Question of the Week => Topic started by: katieHaylor on 21/10/2019 17:13:43

Title: QotW - 19.10.20 - Why does wiping my car windscreen turn water to ice?
Post by: katieHaylor on 21/10/2019 17:13:43

Mike asks:

When the outside temperature is hovering around the freezing mark, the condensation or dew on my automobile windshield is in a liquid state. But if I wipe the windshield, the liquid water changes to ice. Why is that?

Can you help Mike with this one?

Title: Re: QotW - 19.10.20 - Why does wiping my car windscreen turn water to ice?
Post by: Hayseed on 21/10/2019 17:26:47

The surface can absorb the latent heat of the liquid, when you spread the beads out.

Title: Re: QotW - 19.10.20 - Why does wiping my car windscreen turn water to ice?
Post by: alancalverd on 21/10/2019 17:28:49

If undisturbed, supercooled liquid water can form all sorts of metastable short-range polymers that do not crystallise at 0 deg C. It doesn't take much to precipitate crystallisation and the spread can be very rapid, producing feather patterns on a previously-wiped surface in a matter of seconds from a small starting point.

Title: Re: QotW - 19.10.20 - Why does wiping my car windscreen turn water to ice?
Post by: simplex on 29/02/2020 20:26:44

A thin layer of water freezes more quickly that a thick layer.

Title: Re: QotW - 19.10.20 - Why does wiping my car windscreen turn water to ice?
Post by: Paul25 on 19/03/2020 14:27:29

The combination of wind chill and less volume of water to freeze