Page "Pascal (unit)" Paragraph 20

Meteorologists worldwide have for a long time measured atmospheric pressure in bars, which was originally equivalent to the average air pressure on Earth ; the bar was divided into a thousand millibars to provide the precision meteorologists require.

After the introduction of SI units, many preferred to preserve the customary pressure figures.

Consequently, the bar was redefined as 100, 000 pascals, which is only slightly lower than standard air pressure on Earth.

Today many meteorologists prefer hectopascals ( hPa ) for air pressure, which are equivalent to millibars, while similar pressures are given in kilopascals in practically all other fields, since the hecto prefix is rarely used.

Since official metrication, meteorologists in Canada use kilopascals ( kPa ), although in some other countries hectopascals are still in use.