I was looking to see if there was an international definition that everyone knew/used. The ICAO state that it is horizontal vis less than 1000m but that the temp doesnt nessesarily have to be below 0 degrees. The UK Met Office agrrees with this definition and the 1000m or less. However i know that Boeing use 1 statute mile. I presumed that evrybody used the same definition but it does not appear to be the case. Are there any other variations?
cheers
stu