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Wind speed conversion factors. Meteorological data includes wind speeds which may be expressed as statute miles per hour, knots, or meters per second. Here are the conversion factors for those various expressions of wind speed: 1 m/s = 2.237 statute mile/h = 1.944 knots. 1 knot = 1.151 statute mile/h = 0.514 m/s.
Correcting concentrations for altitude. Air pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude. The concentration decrease is directly proportional to the pressure decrease with increasing altitude.
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, 10 ...
Molar concentration (also called molarity, amount concentration or substance concentration) is a measure of the concentration of a chemical species, in particular, of a solute in a solution, in terms of amount of substance per unit volume of solution. In chemistry, the most commonly used unit for molarity is the number of moles per liter ...
An individual score (Individual Air Quality Index, IAQI) is calculated using breakpoint concentrations below, and using same piecewise linear function to calculate intermediate values as the US AQI scale. and The final AQI value can be calculated either per hour or per 24 hours and is the max of these six scores.
Concentration. In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: mass concentration, molar concentration, number concentration, and volume concentration. [1] The concentration can refer to any kind of chemical mixture, but most ...
The EPA reviewed this NAAQS in 1985 and 1996, and in both cases concluded that the existing standard was sufficient. The most recent review by the EPA occurred in 2010, resulting in a new 1-hour NO 2 primary standard set at 100 ppb; the annual average of 0.053 ppm remained the same. Also considered was a new 1-hour secondary standard of 100 ppb.
The atmospheric methane concentration has continued to increase since 2011 to an average global concentration of 1911.8 ± 0.6 ppb as of 2022. [16] The May 2021 peak was 1891.6 ppb, while the April 2022 peak was 1909.4 ppb, a 0.9% increase. [55] Annual atmospheric methane concentrations from 1990 to 2021.