On Mon, 17 Dec 2007 18:02:27 +0000, John Hall wrote in


As for Richard's query, the whiteness on the roads this morning was
simply down to hoar frost. I noticed it too - enough for car tracks to
be quite visible, and untreated pavements especially had a thick white
covering. It wasn't snow, though, simply a case of moister air coming
in during the night with the cloud, I think, and forming rime on the
very cold surfaces. Quite impressive and very wintry-looking though!

The odd thing was that the grass was nowhere near as white, which is the
reverse of what one normally sees with hoar frost.

I think that is because the grass reacts almost as quickly as the air to
the warming, whereas the solid surfaces stay cooler for longer, allowing
the water vapour to collect on them readily.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 17/12/2007 19:33:41 GMT