As previously stated, the visible appearance of exhaled breath depends on air temperature and humidity. Out here in Left Field, whenever within eyeshot of any (perhaps unreliable) outdoor thermometer, I have never seen anyone’s breath above 40° F.
Egregious hijack: regarding ideal gasses within a closed system, the Universal Gas Law states that: P1V1 / T1 = P2V2/ T2.
P1= pressure on gas1. V1=volume of container holding gas1. T1 = temprature of gas1. Similarly, P2= pressure on gas2. V2=volume of container holding gas2. T2 = temprature of gas2.
Variants include:
Charles’ Law: P1 / T1 = P2 / T2, holding volume constant.
Charles, Jacques–Alexandre–César (1746–1823), French physicist. Charles discovered the law that bears his name about 1787, and that discovery constitutes his only major contribution to science. His more significant achievements were in ballooning. He conceived the idea of using hydrogen as the medium of displacement and developed with his brother nearly all the basic features of modern balloon design.
Gay-Lussac’s Law: V1 / T1 = V2 / T2, holding pressure constant
(physics) the density of an ideal gas at constant pressure varies inversely with the temperature
Note: Charles’ Law is often (mis) attributed to Gay-Lussac.
Gay-Lussac, Joseph Louis. 1778-1850.
French chemist and physicist who isolated the element boron (1809) and formulated a law that explains the behavior of a gas under constant pressure.
Boyle’s Law: P1 * V1 = P2 * V2, holding temperature constant.
Boyle, Robert. 1627-1691.
Irish-born British physicist and chemist whose precise definitions of chemical elements and reactions began the separation of chemistry from alchemy. In 1662 he formulated Boyle’s law.