In article ,
jbm wrote:

Hoar frost
The white crystals seen on the grass on a cold morning are neither a ground
nor an air frost. This is a 'hoar frost', which forms when the air cools and
water condenses onto the grass.

Interestingly enough, in the UK, that is 70% wrong. Most of the
condensation (and hence hoar frost) is water that evaporates from
the ground and condenses onto the grass.


Regards,
Nick Maclaren.