Avogadro's law "P" are taken at standard conditions for temperature and pressure (STP), then "k"'=1/"n", where "n" is Loschmidt constant. Avogadro's hypothesis (as it was known originally) was formulated in the same spirit of earlier empirical gas laws like Boyle's law (1662), Charles's law (1787) and Gay-Lussac's law (1808). The hypothesis was first published by Amadeo Avogadro in 1811, and reconciled Dalton atomic theory with the "incompatible" idea of Joseph Louis Gay-Lussac that some gases were composite of different fundamental substances (molecules) in integer proportions. In 1814, independently from Avogadro, André-Marie Ampère published the same law with similar conclusions. As Ampère was
Potential temperature 1st law simplifies to: For approximately ideal gases, such as the dry air in the Earth's atmosphere, the equation of state, formula_18 can be substituted into the 1st law yielding, after some rearrangement: where the formula_20 was used and both terms were divided by the product formula_21 Integrating yields: and solving for formula_23, the temperature a parcel would acquire if moved adiabatically to the pressure level formula_24, you get: The potential virtual temperature formula_26, defined by is the theoretical potential temperature of the dry air which would have the same density as the humid air at a standard pressure P.