Atmosphere Overview

The layer of gases that surrounds our planet is called the atmosphere. The atmosphere is composed of 78% nitrogen, 21% oxygen and 1% other gases. Water vapor and tiny particles of dust, smoke and other chemicals are also found in the atmosphere.

The Earth is unique because it has an atmosphere that can support life. Oxygen and gases in the air are necessary for survival. The atmosphere also traps the sun’s energy to maintain moderate temperatures and forms a protective layer from the sun’s radiation.

The force that atmospheric gases exert on a surface is called air pressure, or atmospheric pressure. This pressure is highest near sea level because gravity pulls the air molecules close to the Earth’s surface. As the altitude increases, the air pressure decreases.

Humans add pollutants into the atmosphere every day. Natural sources of air pollution include volcanic ash, pollen and wildfire smoke. Air pollutants can travel great distances and impact environments around the globe.