Question

What is meant by IMB?

Answer 1

Hint:
i) Mb is equal to millibar.
ii) It is a unit of pressure.
iii) 1 mb is equal to 100 Pascal.

Complete answer:
Imb here refers to the term milli bar. It is a unit of pressure where 1 mb= 100 Pascal. The word bar has its origin from the Greek word, meaning weight. Scientific symbol of the unit is bar; the earlier symbol b is now deprecated and clashes with the use of b to denote the unit barn, but to denote the millibar is still encountered, especially as mb (rather than the correct mbar).

In an early iteration of the metric system, between 1793 and 1795, the term bar was used for a unit of weight. It is a pressure unit metric, but not part of the International System of Units (SI). It is defined as exactly equal to 100,000 Pa (100 kPa), or slightly less than the actual average sea level pressure (around 1,013 bar).

By the barometric formula, at an altitude of 111 meters at 15 °C, 1 bar is approximately the atmospheric pressure on Earth. Megabar, kilo bar, decibar, centibar, and millibar are units derived from the bar. Gauge pressure, i.e. pressure in bars above ambient or atmospheric pressure, is expressed by the notation bar (g), though deprecated by different bodies.

Note:
i) The Norwegian meteorologist Vilhelm Bjerknesnes first introduced the bar and the millibar.
ii) Many engineers around the world use the bar as a pressure unit because using pascals would mean using very large numbers in most of their work.
iii) 1 millibar = 1 hectopascal (1 hPa = 100 Pa).