Definition of spectrometer. 1  1 : an instrument used for measuring wavelengths of light spectra. 2  2 : any of various analytical instruments in which an emission (as of particles or radiation) is dispersed according to some property (as mass or energy) of the emission and the amount of dispersion is measured nuclear magnetic resonance spectrometer.
1 bar is equal to 1000 millibars. Just like how there are 1000 millilitres in a litre, and 1000 milliseconds in a second. 1 millibar = 0.001 bars.
Most National Weather Service measurements are given in inches of mercury. At sea level, standard air pressure is 29.92 inches of mercury and 1,013 millibars. Inches of mercury is measured in how high a column of mercury rises in a barometer.One millibar is equivalent to one-thousandth of a single bar, or 1,000 dynes.