Atmospheric density refers to the mass of air per unit volume in Earth's atmosphere. It is a key parameter in meteorology and atmospheric science as it affects the behavior of weather systems and the transmission of electromagnetic radiation. Atmospheric density varies with altitude, temperature, and pressure, with the highest density found at sea level and decreasing with increasing altitude. Understanding atmospheric density is important for predicting weather patterns, aircraft performance, satellite orbits, and the behavior of various atmospheric pollutants. Researchers study atmospheric density through various observational and modeling techniques to improve our understanding of Earth's atmosphere and its interactions with other Earth systems.