structural:summarization
Abbreviations

The abbreviation CH -C can mean the mass of carbon contained in a mass of methane, and the mass of methane is always 1.33 times the mass of CH -C. CH -C can also mean the methane-carbon ratio, which is 1.33 by mass. Methane at scales of the atmosphere is commonly measured in teragrams (Tg CH) or millions of metric tons (MMT CH), which mean the same thing. Other standard units are also used, such as nanomole (nmol, one billionth of a mole), mole (mol), kilogram, and gram.