Composition of the Atmosphere • The atmosphere is a mixture of gases surrounding Earth. • Nitrogen (78%), the most common atmospheric gas, is released when dead plants and dead animals break down and also when volcanoes erupt. • Oxygen (21%), the second most common atmospheric gas, is made by phytoplankton and plants. • The remaining 1% of the atmosphere is made up of argon, carbon dioxide, water vapor and other gases.
Air Pressure (Atmospheric Pressure) • Gravity pulls gas molecules toward Earth, causing Air Pressure, which is the force with which air molecules push on a surface. • Strongest at Earth’s surface • Air Pressure decreases as altitude increseses
Temperature • Also changes as altitude increases • The composition of atmospheric layers affect their temperature. • The temperature differences result from the amount of gases present in each layer that absorb solar energy • As the amount of gases that absorb solar energy increases, the temperature increases
Layers of the Atmosphere • The Earth’s atmosphere is divided into five layers based on their composition. TheSilly MouseTookEx-lax RTEH X ORSE O PAOR S OTSM P SOPO H PSH S E HPEP R E HRH E REE E ER R EE
Troposphere • Lowest layer of the atmosphere, lying next to Earth’s surface. Temperature decreases with altitude. • Contains almost 90% of the atmosphere’s mass. • Nearly all weather occurs in this layer. • Water vapor, clouds, air pollution, and organisms are also found here.
Stratosphere • The atmospheric layer above the troposphere. • Contains little moisture • Lower stratosphere is extremely cold, but temperature increases as altitude increases in the stratosphere. • The Ozone Layer- The upper layer of the Stratosphere. • it absorbs UV radiation from the sun, warming the air protects life on Earth.
Mesosphere • The middle layer of the atmosphere. • Coldest layer • Temperature decreases as altitude increases, just like the troposphere. • The upper layer of the Mesosphere (lower portion of the Thermosohere) is called the Ionosphere
Ionosphere • The lower part of the thermosphere is considered the Ionosphere. • As a result of N2 atoms and O2 atoms absorbing the radiation, temperature in the thermosphere rises, and gas particles become electrically charged ions. • Ions within the ionosphere can radiate energy as shimmering lights called auroras, a.k.a. the Northern and Southern Lights.
Thermosphere • Uppermost atmospheric layer. • Temperature again increases steadily with altitude because nitrogen and oxygen atoms absorb solar radiation. • This releases thermal energy. • No data to determine its upper boundary. • Blends with the vacuum of space (exosphere).
Exosphere • The last layer of the atmosphere. Very difficult to determine where it stops and space begins • Very few atoms in this layer of the atmosphere
Videos • Antarctica Auroras • Aurora Northern Lights as seen from Space