Inset from the Meteorological Glossary
Did you know that a minimum air temperature of 0.0°C is NOT a frost? An air frostair frost An air frost occurs when the temperature of the air falls below 0.0°C only occurs when the air temperature in a Stevenson screen falls below zero celsius i.e. goes negative and not before. The Met OfficeUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy website in an item about the types of frost is wrong. I did inform them of the fact and they have promised to correct it.
The UKMOUKMO The Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy are in pretty good company not understanding what the exact definition of frost is, neither do the “experts” down at the Royal Meteorological Society either. I informed them about this slip up on their website a while ago, but so far the haven’t bothered to reply.
I notice that the Royal Meteorological Society have now corrected the ‘Touch of frost’ article on their website about the definition of what an air frost is, but not so much as a thank you from them. At least I did get a reply from the Met Office help desk, but it still hasn’t been corrected on their website the last time I looked.
I was astounded to find when I bought the book by the Met Office called ‘Very British Weather’ to add to my collection of books on weather and climate, that they had it wrong too.
On page 181 of the book I notice it states that ‘freezing conditions’ occur ‘when the temperature is at or below 0°C’. There’s no arguing that 0.0°C is the freezing point of water, but ‘freezing conditions’, even an ‘air frost’, surely can’t occur until the air temperature is below that temperature, and not at it. It’s a small even a trivial point, but these three instances are or were all wrong. I’m still trying to understand what the paragraph at the foot of the page is trying to say.😉
