Atmosphere The envelope of gases that surrounds the Earth Composed of: Nitrogen (78%) Oxygen (21%) Carbon Dioxide (0.04%) Water Vapor (0.5%) Other Gases

Layers of the Atmosphere The Earth’s atmosphere is divided into five basic layers: Troposphere Stratosphere Mesosphere Thermosphere Exosphere

Air Pressure/Air Particles Most of the air particles in the atmosphere can be found in the troposphere Troposphere has high air pressure Thermosphere has few air particles and very low air pressure

Temperature Changes If Earth’s atmosphere is invisible, how can we divide it into different layers? We divide the atmosphere into different layers based upon changes in temperature

Troposphere Layer closest to the Earth Contains most of the air particles because gravity pulls them down Only layer that has weather Layer in which we live

Stratosphere 10-50 Km above the Earth Contains the “Ozone Layer”- protects us from the sun’s UV rays Airplanes prefer to fly here Temperature rises slowly as you go higher

Mesopshere 50-85 Km Temperatures drop greatly in this layer Coldest temperatures in the atmosphere Contains a layer of charged particles called the “ionosphere”- This allows radio/tv signals to work

Thermosphere Over 85-300 Km above the Earth Thinnest layer- particles very spread out Temperatures rise as you go higher- hottest layer Where the Northern Lights occur

Aurora Borealis (Northern Lights)

Exosphere Over 300 Km above Earth Beginning of outer space Where satellites fly