It may sound a daft question, but I just want to clarify, I recorded
0.0c here in Teignmouth last night, does it count as an air frost, I
would say yes?

On Sun, 23 Dec 2007 13:55:36 -0800 (PST), Bonos Ego wrote in


It may sound a daft question, but I just want to clarify, I recorded
0.0c here in Teignmouth last night, does it count as an air frost, I
would say yes?

No. For you to record an air frost, it has to be below zero.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 23/12/2007 22:06:06 GMT

"Mike Tullett" wrote in message ...
No. For you to record an air frost, it has to be below zero.
It's a shame that digital thermometers don't display the (probably
mathematically incorrect) -0.0C as there's a tiny window of negative numbers
which will round up to 0.0C rather than down to -0.1C. (Technically anything
from -0.00...1 to -0.0499... - okay, not exactly a great range but it still
means once in a blue moon a frost will have been missed due to rounding).

On Mon, 24 Dec 2007 09:33:09 -0000, Darren Prescott wrote in


No. For you to record an air frost, it has to be below zero.

It's a shame that digital thermometers don't display the (probably
mathematically incorrect) -0.0C as there's a tiny window of negative numbers
which will round up to 0.0C rather than down to -0.1C. (Technically anything
from -0.00...1 to -0.0499... - okay, not exactly a great range but it still
means once in a blue moon a frost will have been missed due to rounding).

Not only would one need a high resolution sensor/display, but one which is
probably more accurate than is currently possible.

--
Mike Tullett - Coleraine 55.13°N 6.69°W posted 24/12/2007 10:02:02 GMT

On Mon, 24 Dec 2007 10:02:02 +0000, Mike Tullett
wrote:

On Mon, 24 Dec 2007 09:33:09 -0000, Darren Prescott wrote in


No. For you to record an air frost, it has to be below zero.

It's a shame that digital thermometers don't display the (probably
mathematically incorrect) -0.0C as there's a tiny window of negative numbers
which will round up to 0.0C rather than down to -0.1C. (Technically anything
from -0.00...1 to -0.0499... - okay, not exactly a great range but it still
means once in a blue moon a frost will have been missed due to rounding).

Not only would one need a high resolution sensor/display, but one which is
probably more accurate than is currently possible.

Yes, calibrated instruments would be in trouble for accuracy so such
readings would be pretty meaningless. Not to mention microclimate, I
won't even go there. It's hard enough to get things right to the
nearest tenth, never mind hundredths and in some conditions, the
temperature inside official screens will be a degree or two different
from the true air temperature yet this is known about and is
accepted.

I'm not a fan of decimals never mind hundredths, they make me nervous
(yet the GW debate depends on them).

--
Dave

Dave Ludlow wrote:

Yes, calibrated instruments would be in trouble for accuracy so such
readings would be pretty meaningless. Not to mention microclimate, I
won't even go there. It's hard enough to get things right to the
nearest tenth, never mind hundredths and in some conditions, the
temperature inside official screens will be a degree or two different
from the true air temperature yet this is known about and is
accepted.

Accuracy only really applies when comparing one instrument to another.
Resolution of the instrument is a different matter and is generally
finer than the accuracy (0.1degC vs. +/-0.5degC).

I'm not a fan of decimals never mind hundredths, they make me nervous
(yet the GW debate depends on them).

For a discrete reading, then probably true. When averaging over many
readings, -0.0C (or -0C) conveys meaning that has been hidden in the
rounding of the value.

--
Jonathan Stott
Canterbury Weather: http://www.canterburyweather.co.uk/
Reverse my e-mail address to reply by e-mail

On 24 Dec, 14:02, Jonathan Stott wrote:
Dave Ludlow wrote:
Yes, calibrated instruments would be in trouble for accuracy so such
readings would be pretty meaningless. Not to mention microclimate, I
won't even go there. It's hard enough to get things right to the
nearest tenth, never mind hundredths and in some conditions, the
temperature inside official screens will be a degree or two different
from the true air temperature yet this is known about and is
accepted.

Accuracy only really applies when comparing one instrument to another.
Resolution of the instrument is a different matter and is generally
finer than the accuracy (0.1degC vs. +/-0.5degC).


Oh no, you remind me of the first question that I was asked on an ASO/
SO promotion board :-

"What is the difference between accuracy and precision?"