"Ken Cook" wrote in message
...
"Graham Easterling" wrote in message
...

1 air frost (0.0 degrees!)

Hi, Graham,

Sorry, but 0.0C is not a frost. That is the melting point, not freezing
point. A frost needs a negative sign in front of the number.

I was going to make the same point. Curiously, when I was an observer
at an auxiliary synoptic station decades ago, the accepted way round
this was to report -0.0 if the meniscus was marginally short of the zero
line, but not by enough to call it -0.1. After a long interval, when I
became responsible for a climatological station I did this, and had it
sent back as an error (this was when they still sent back an error
form and asked for your comments). Apparently the computer is not
programmed to accept -0.0. Under these circumstances I now
report -0.1.

Philip Eden