On Thu, 17 Apr 2008 12:57:57 GMT, Larry Dighera
wrote:

On Thu, 17 Apr 2008 02:20:46 -0700 (PDT), terry
wrote in
:

I am confused by this practice commercial nav question. ( at least I
am confused by the answer in the book which was b. but I think both a
and c are correct), but I appreciate some other opinions.

Day 1 Altimeter reads elevation of 1390 feet with 1013 HPa set on
subscale

http://en.wikipedia.org/wiki/Mbar
Atmospheric air pressure is often given in millibars where
"standard" sea level pressure is defined as 1013.25 mbar (hPa),
equal to 1.01325 bar. Despite millibars not being an SI unit, they
are still used locally in meteorology in some countries to
describe atmospheric pressure. The SI unit is the pascal (Pa),
with 1 mbar = 100 Pa = 1 hPa = 0.1 kPa. Meteorologists worldwide
have long measured air pressure in millibars. After the
introduction of SI units, others use hectopascals (which are
equivalent to millibars) so they could stick to the same numeric
scale. Similar pressures are given in kilopascals in practically
all other fields, where the hecto prefix is hardly ever used. In
particular, Canadian weather reports use kilopascals (which could
also be called centibars).


Torricelli started it all off. if you are the first guy in the world
with a barometer what do you call the measure of the atmospheric
pressure measured on that barometer. a bar(ometer). divide the value
into a thousand to give you some nice fine numbers to measure with and
you have the millibar.

pascal is just a johhny come lately in pressure measurements.

the poms worked out that 14.8lbs per square inch = 1 bar(ometer)

Stealth ( I'm with torricelli) Pilot