airmass
airmass Lexical Profile
airmass Game Scores & Validity
• noun
A large volume of air in the atmosphere that is mostly uniform in temperature and moisture, often covering hundreds or thousands of square miles.
"A cold, dry polar airmass moved southward across the plains, bringing a sharp drop in temperature."
In astronomy and solar energy, a measure of the optical path length that light from a celestial source travels through Earth's atmosphere, expressed relative to the path length directly overhead at the zenith.
"Astronomers prefer to observe faint galaxies when they are high in the sky at a low airmass to minimize atmospheric distortion."
Word Nuance & Usage
In general meteorology, the open compound 'air mass' is more common, whereas the closed spelling 'airmass' is frequently used in astronomy (to measure atmospheric thickness along a line of sight) and as an attributive modifier (as in 'airmass thunderstorm').