Am I right in thinking that if the temperature is below freezing at 9am
(when observations for one day end) then it would count as two days with
air frost rather than one?

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

Jonathan Stott wrote:
Am I right in thinking that if the temperature is below freezing at 9am
(when observations for one day end) then it would count as two days with
air frost rather than one?

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

Hi, Jonathan,

If you are working to Met O climatological station rules of 24 hour,
09Z - 09Z obs, then that is correct. If you are working to 00Z - 00Z,
then the temperature at midnight would be the deciding factor, or 18Z -
18Z at 18Z and so on, depending on the obs hour.

It is a misleading reading, especially if the following night is mild,
as this one will be, but unavoidable at the majority of climatological
stations that are visited only once each day at 09Z. As far as the
record books go the coming night will have an air frost whatever
happens and the max for today will probably be at 09Z tomorrow morning
(thrown back)!

A more accurate 12 hour method is used at some synop. sites where the
max refers to 09Z - 21Z and the min 21Z - 09Z.

HTH

Ken Cook, Copley 253 metres asl, nr Barnard Castle, County Durham
http://mysite.wanadoo-members.co.uk/copley

In message . com, Ken
Cook writes

Jonathan Stott wrote:
Am I right in thinking that if the temperature is below freezing at 9am
(when observations for one day end) then it would count as two days with
air frost rather than one?

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

Hi, Jonathan,

If you are working to Met O climatological station rules of 24 hour,
09Z - 09Z obs, then that is correct. If you are working to 00Z - 00Z,
then the temperature at midnight would be the deciding factor, or 18Z -
18Z at 18Z and so on, depending on the obs hour.

It is a misleading reading, especially if the following night is mild,
as this one will be, but unavoidable at the majority of climatological
stations that are visited only once each day at 09Z. As far as the
record books go the coming night will have an air frost whatever
happens and the max for today will probably be at 09Z tomorrow morning
(thrown back)!

A more accurate 12 hour method is used at some synop. sites where the
max refers to 09Z - 21Z and the min 21Z - 09Z.

Even the 12-hour method isn't foolproof. It occasionally happens that
the 24-hour min occurs sometime between 0900z and 2100z and would
therefore be missed by the 12-hour method. Similarly, the 24-hour max
occasionally occurs between 2100z and 0900z.

There's no perfect method. What is important is to have a system and
stick to it but if yopu want your data to be comparable to that from the
majority of other stations then the 0900z-0900z system is the one to
use.

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles 85m a.s.l.
England

There's no perfect method. What is important is to have a system and
stick to it but if yopu want your data to be comparable to that from the
majority of other stations then the 0900z-0900z system is the one to
use.

Norman.
(delete "thisbit" twice to e-mail)
--
Norman Lynagh Weather Consultancy
Chalfont St Giles 85m a.s.l.
England

Could you remind me if that's recorded under the date of the start or the
finish of the period for both

Thanks
Dave.

Forgive the stupid question, but why do we all put a "Z" after all times?

I have always assumed that "Z" = "GMT" but what exactly does "Z" mean?

Brendan

"Brendan DJ Murphy" wrote in message
...
Forgive the stupid question, but why do we all put a "Z" after all times?

I have always assumed that "Z" = "GMT" but what exactly does "Z" mean?

Brendan

Z = zulu time = UTC

http://hurricanes.noaa.gov/zulu-utc.html

Joe

In article ,
says...
Forgive the stupid question, but why do we all put a "Z" after all times?

I have always assumed that "Z" = "GMT" but what exactly does "Z" mean?

Brendan



http://www.maybeck.com/ztime/

--
Harold Brooks
hebrooks87 hotmail.com

In message , Brendan
DJ Murphy writes
Forgive the stupid question, but why do we all put a "Z" after all times?

I have always assumed that "Z" = "GMT" but what exactly does "Z" mean?

Brendan


From the military use to indicate which time zone is in use:

Z (referred to as zulu time) = GMT

and then A = GMT + 1 hour
B = GMT + 2

etc

Normally used thus: 280845Z Nov = 28 Nov 08:45 GMT


--
Chris

"Joe Hunt" wrote in message
...

"Brendan DJ Murphy" wrote in message
...
Forgive the stupid question, but why do we all put a "Z" after all
times?

I have always assumed that "Z" = "GMT" but what exactly does "Z"
mean?

Brendan

Z = zulu time = UTC

http://homepage.ntlworld.com/booty.weather/FAQ/SZ.htm#Z

The globe is divided up into 15degree time zones, each having a unique
letter; the zone immediately to the east of us here in the BI is 'A' (or
Alfa), hence when UK is on GMT+1hr during BST, then reporting in local
time you would put 0824A etc. Z is reserved for the 'primary' zone
centred on the Greenwich meridian.

Martin.

Dave.C wrote:

Could you remind me if that's recorded under the date of the start or the
finish of the period for both

Thanks
Dave.

Hi, Dave,

The max reading taken at 09Z is thrown back to the day before (today's
max will be the 24 hours to 09Z tomorrow)

The min reading is logged for that day (today's min was the 09Z this
morning reading)

Rainfall read at 09Z is thrown back to the day before ( today's
rainfall is what is in the pot tomorrow morning)

Best wishes,

Ken, Copley, nr Barnard Castle