On 26/03/2013 18:22, djc wrote:
On 26/03/13 13:25, polygonum wrote:

Considering how long we have had people recording the weather (Fitzroy
systematically - and many, many others with varying accuracy and
completeness over at least many centuries), I fail to understand why
they keep referring to "since records began" as referring to a period
within my own lifetime. Have they thrown all the old records out? Have
they decided that the standards to which they were made are not
compatible? If they have done that, then they need to be much more
forthcoming about what they actually mean.

It is always difficult to reconcile any 'long series' or records, in any
subject. What instruments were used, how were they calibrated,
conversion factors, where, in what circumstances, language, terminology,
reliability of witnesses, discontinuity of records etc..

In the case of sea surface temperatures, the regular records go back to
the early 19th Century, with occasional readings before that. Early
measurements were normally taken using a canvas bucket thrown over the
side and left in the wind on deck while the temperature was measured, so
an unknown amount of evaporative cooling occurred. Later ones were
normally taken using a wooden or metal bucket, so there was less
evaporative cooling. Later still, they fitted a thermometer to the
engine cooling water intake, so not only did the water come from deeper
down, there was no evaporative cooling. These readings show a rising
trend with noticeable "steps", unsurprisingly. The current method using
satellites can only measure the temperature of the top few microns of
water. They don't seem to agree very well with any of the other methods.

There was an air temperature measuring station at Heathrow when it fist
opened as an air base with a grass field. Now, the meauring station,
while in the same place geographically, is surrounded by tarmac and
concrete surfaces. It reads both hotter and colder extremes than the
earlier version. Make of this what you will.

I can remember the winter of '63€” at least I remember lots of snow at
the age of ten, but not cold, no central heating, frost on the window
panes in the mornings was just normal. Thinking back, it was probably
that winter that prompted my parents to install (coal-fired) heating.
My mother said it was not as cold as '47. Did my grandparents experience
colder? I don't know.

'47 was allegedly colder than '63, which is the first really cold winter
I remember.

I don't remember feeling colder for as long at any time since then.
--
Tciao for Now!

John.