I think the reason why some people "disapprove" of the hPa unit is because
the prefixes which are powers of 1000 (10^-6=micro, 10^-3=milli, 1,
1000=kilo, 10^3=mega, 10^9=giga etc) are generally preferred.


On Mon, 18 Oct 2004, Icebound wrote:


"Gene Nygaard" wrote in message
...

Naturally. Those obsolete units didn't even fit in with the cgs
predecessors of SI, the modern metric system, the International System
of Units which was introduced 43 years ago. The cgs unit of pressure
was the barye (a millibar is a kilobarye, or 1000 dyn cm/s²).

There has, of course, been considerable pressure to get rid of those
obsolete millibars. If it weren't for that, we wouldn't have the
problem that the OP is complaining about. Unfortunately, those
applying the pressure to get rid of millibars as pressure unit weren't
smart enough to explain what the proper SI units would be (i.e., the
units used by Canada in their public weather reports, the units I hear
used on Canadian TV and radio: kilopascals). This left the door open
for this screwball scheme to hang onto millibars by disguising them
under a pseudo-SI name.


If the barye is an official cgs unit, then what makes the BAR, 1,000,000
dynes per square cm, any less official.
and a 1,000th of a bar is a millibar, and hence just as official as the
barye.

The kilopascal came to be the unit of media "choice" in Canada, only because
the bureaucrats liked their numbers to be in the range 0 to 999. Since
"normal" atmospheric pressure at sea level is approximately 101.2
kilopascals, they loved it and decreed the kP to be "official". 1,012 was
just too large a number for a them.

However, to represent meteorological change, the kilopascal is useless: for
example, the change from 101 to 104 kilopascals is HUGE, meteorologically
speaking, but the measly 3 units (numerically) does not show that
adequately.

Therefore hectopascals will continue to be the unit of choice for
meteorologists, I am sure, in order to show significant change as a
significant numerical difference.

...and of course they probably WOULD rather just call them millibars as
they have for a few hundred years... but all you correctness police have
foisted the PASCAL upon them and so they now have to prevent any further
public confusion by at least using the same base unit, albeit with a
different sub-multiple.

Hectopascals, forever!