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One part per hundred thousand, per cent mille (pcm) or milli-percent denotes one part per 100,000 (10 5) parts, and a value of 10 −5. It is commonly used in epidemiology for mortality, crime and disease prevalence rates, and nuclear reactor engineering as a unit of reactivity.
1 volume percent = 10,000 ppmv (i.e., parts per million by volume) with a million being defined as 10 6. Care must be taken with the concentrations expressed as ppbv to differentiate between the British billion which is 10 12 and the USA billion which is 10 9 (also referred to as the long scale and short scale billion, respectively).
Values are given as pollution free monthly mean mole fractions in parts-per-billion. [1] Atmospheric methane is the methane present in Earth's atmosphere. [2] The concentration of atmospheric methane is increasing due to methane emissions, and is causing climate change. [3] [4] Methane is one of the most potent greenhouse gases.
The concentrations of carbon dioxide in the atmosphere are expressed as parts per million by volume (abbreviated as ppmv, or ppm(v), or just ppm). To convert from the usual ppmv units to ppm mass (abbreviated as ppmm, or ppm(m)), multiply by the ratio of the molar mass of CO 2 to that of air, i.e. times 1.52 (44.01 divided by 28.96).
The word promille is the cognate in Dutch, German, Finnish and Swedish, and is sometimes seen as a loanword in English with the same meaning as per mille. [7] [4] The symbol is included in the General Punctuation block of Unicode at U+2030 ‰ PER MILLE SIGN. [5] There is also an Arabic-Indic per mille sign at U+0609 ؉ ARABIC-INDIC PER MILLE SIGN.
Jeff Bezos, Elon Musk say human population not nearly big enough: ‘If we had a trillion humans, we would have at any given time a thousand Mozarts’ Steve Mollman December 16, 2023 at 9:01 AM
By using a laser that is locked to an atomic transition, a CCD or PMT will detect the laser induced fluorescence to allow highly selective, parts-per-trillion to parts-per-quadrillion concentration measurement with single atom detection. [1]
The examples don't seem to be too accurate. A drop is usually defined as 0.05 ml, which then gives;. 1 drop in 50 ml = 1‰, 50ml is a very small cup 1 drop in 50 l = 1ppm 50 l is about 11 gallons, not 40 1 drop in 50 cubic metres = 1 ppb 1 drop = 1ppt, a 50 m swimming pool is 50*25*2 = 2,500 m^3 1 drop in 50,000,000 cubic metres = 1ppq, 50,000,000 m^3 is equivalent to a lake covering a square ...