A mixture of gases surrounding the Earth. Atmosphere A mixture of gases surrounding the Earth.

Atmosphere Composition Composition of Earth’s Atmosphere: 78% Nitrogen 21% Oxygen 1% Other

Air Pressure All the molecules in the air have mass. Air molecules are pulled to the Earth’s surface by gravity. Since air molecules are pulled to the Earth’s surface, sea level is where air is most dense.

Air Pressure Since air molecules sink to the Earth’s surface, that is where air pressure is the highest.

Layers of the Atmosphere Troposphere Lowest layer of the atmosphere Most dense layer of atmosphere Where weather happens Temperature decreases as altitude increases

Layers of the Atmosphere Stratosphere: Layer above the troposphere Temperature increases as altitude increases. This occurs because the ozone layer, found at the top of the stratosphere, absorbs ultraviolet radiation from the sun, which warms the air.

Layers of the Atmosphere Mesosphere: The layer between the stratosphere and the thermosphere. Temperature decreases as altitude increases. The Mesosphere is the coldest layer of the atmosphere.

Layers of the Atmosphere Thermosphere: The uppermost layer of the atmosphere. Temperature increases as altitude increases. Atoms of nitrogen and oxygen absorb high-energy solar radiation and release thermal energy. Show Visual Concepts

Atmospheric Heating