It happens here occasionally, and without fog. I have been putting it down
to the fact that the grass has been allowed to grow too long and then people
have been pushing the bulb down into the grass instead of having the bulb
just touching the tips of the blades of grass, which should be short.
Pushing the bulb into too long grass shelters the bulb, while it is the top
of the grass which takes the radiation cooling.

There was a talk by David Attenborough on Radio 4 this morning in which he
told of a species of ant which is very sensitive to heat. Normally, in this
particular field where the colony of these ants was, sheep had been keeping
the grass short, but when the sheep were excluded from the field and the
grass grew longer as a result, the ants overheated and the colony died out.

There are probably several possible causes of this phenomenon, eg fog, as
has been mentioned.

Ian Bingham,
Inchmarlo, Aberdeenshire.

"whitehead1972" wrote in message
...
Mornin' all (again). Today I recorded a minimum temperature of 8.2c on
my Oregon Scientific thermo. My Casella sheathed alcohol thermometer,
however, recorded a minimum of 9c. Is it possible that the grass
temperature can be higher than the air temperature?
The previous night's readings were 6.2c (air) and 5.5c (grass).
The site of the grass minimum is not Met Office standard (my garden's
not big enough) being situated close to a sheltered gravel board fence
and shrubs. The ground make up is imported loam over a clay base.