Boyle's law of the gas, and "k" is a constant. The equation states that the product of pressure and volume is a constant for a given mass of confined gas and this holds as long as the temperature is constant. For comparing the same substance under two different sets of conditions, the law can be usefully expressed as The equation shows that, as volume increases, the pressure of the gas decreases in proportion. Similarly, as volume decreases, the pressure of the gas increases. The law was named after chemist and physicist Robert Boyle, who published the original law in 1662. This relationship
Potential temperature Potential temperature The potential temperature of a parcel of fluid at pressure formula_1 is the temperature that the parcel would attain if adiabatically brought to a standard reference pressure formula_2, usually 1000 millibars. The potential temperature is denoted formula_3 and, for a gas well-approximated as ideal, is given by where formula_5 is the current absolute temperature (in K) of the parcel, formula_6 is the gas constant of air, and formula_7 is the specific heat capacity at a constant pressure. formula_8 for air (meteorology). The concept of potential temperature applies to any stratified fluid. It is most frequently used in the