luft

Luft is the German word for air, the gaseous mixture that surrounds Earth and is essential for life, weather, and many engineering processes. In German, Luft appears in everyday language and forms the basis for many compound terms, such as Luftfahrt (aviation), Luftdruck (air pressure), Luftqualität (air quality), and Frischluft (fresh air).

Chemically, dry air is mainly nitrogen (about 78 percent) and oxygen (about 21 percent), with argon, carbon dioxide, neon, helium and other trace gases making up the remainder. Air is a compressible fluid whose properties vary with altitude, temperature, humidity and pollution. At sea level, dry air has a density of about 1.225 kilograms per cubic meter and a standard pressure of 1013 hectopascals.

Air data are central to meteorology, climatology and aviation. Measurements include temperature, humidity, density, composition and pollutants. Wind, driven by pressure differences, redistributes heat and moisture and fuels weather patterns. Air quality is a public-health concern in many regions and is monitored to inform policy and personal decisions.

Etymology and usage: Luft derives from the Germanic roots related to breath and wind, with cognates in related languages. The word appears in numerous German compound nouns and is used across science, engineering, and culture to denote atmosphere, ventilation, and the general concept of air.