Bar (unit) mb (rather than the proper mbar) to denote the millibar. Between 1793 and 1795, the word bar was used for a unit of weight in an early version of the metric system. Atmospheric air pressure is often given in millibars, where standard atmospheric pressure at sea level is defined as 1013.25 mbar, 101.325 kPa, 1.01325 bar, which is about . Despite the millibar not being an SI unit, meteorologists and weather reporters worldwide have long measured air pressure in millibars as the values are convenient. After the advent of SI units, some meteorologists began using hectopascals (symbol hPa) which are
Sixteen-bar blues Sixteen-bar blues The sixteen-bar blues can be a variation on the standard twelve-bar blues or on the less common eight-bar blues. Sixteen-bar blues is also used commonly in ragtime music. Most sixteen bar blues are adapted from a standard twelve-bar progression. The standard twelve-bar blues progression is where each cell in the table represents one measure (or "bar"), "I" represents the tonic chord, "IV" the subdominant chord, and "V" the dominant chord. Twelve-bar progressions are formed by applying one of several formulae, including the following. One adaptation extends the first section of tonic chords (bars 1–4) by doubling or repeating