Canadian climate at 52N has not recorded a frost yet this winter! (place, freeze)
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Probably a combination of low winter dewpoints and a small diurnal range.
Here a winter day can have a air temp of 15C with a dewpoint of 10C, which can fall to 2C by about sunset. The high rate of radiational cooling, combined with plenty of moisture, means heavy white frosts are common here, even on nights above OC
Motueka averages 39 air frosts and 119 ground frosts a year.
Most of England has between 100 and 125 ground frosts. Ditto for Wales and NI. Most of Scotland has 125 to 150.
I still don't get it. There's frost on the ground yet it doesn't count as frost?
Well it does, but if the air temperature is above 0C we call it a ground frost, (as the ground temperature, or temperature of surfaces has fallen to 0C or below) "Proper" frosts we only class as air frosts, where the air temperature has fallen below 0C...
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Originally Posted by dunno what to put here
Most of England has between 100 and 125 ground frosts. Ditto for Wales and NI. Most of Scotland has 125 to 150.
On the Met Office regional averages maps Portsmouth falls into the 25-70 ground frosts bracket, but here I don't even record as many as 25 ground frosts in an average winter.. The days of air frosts average is 5-25 days & again Portsmouth is closer to 5 days than 25...
Well it does, but if the air temperature is above 0C we call it a ground frost, (as the ground temperature, or temperature of surfaces has fallen to 0C or below) "Proper" frosts we only class as air frosts, where the air temperature has fallen below 0C...
Why would an air frost be a proper frost? At least, here frost usually refers to seeing frost on the ground not the air temperature so ground frost would be a real frost to me. The US weather service uses frosts to refer to ground frosts only. So I assume "proper" frosts = ground frost.
Why would an air frost be a proper frost? At least, here frost usually refers to seeing frost on the ground not the air temperature so ground frost would be a real frost to me. The US weather service uses frosts to refer to ground frosts only. So I assume "proper" frosts = ground frost.
It's how we do it over here. We differentiate between ground frosts & air frosts, but we we call all visible frosts as frosts too...
In the UK when we refer to a frost we are generally talking about an air temperature of below 0C, this is of course more important to gardeners/growers than a ground frost that can occur at a temperature of a few degrees above freezing.
This is how our Met Office classes different frosts:
I knew the UK had air frosts and ground frosts, but assumed frosts usually meant "ground frost". Air frosts in the US are called "freezes". Frosts usually refers to only "ground frosts".
I knew the UK had air frosts and ground frosts, but assumed frosts usually meant "ground frost". Air frosts in the US are called "freezes". Frosts usually refers to only "ground frosts".
It can get a bit confusing as any visible frost is referred to as a frost, but weather forecasts will mention ground or air ones. I always have made the distiction between the two as well, but I guess to the average Joe a frost is just a frost
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