Atmosphere Atmosphere Basics Combination of gases dust water

Atmosphere

Atmosphere Basics Combination of gases, dust, water droplets, and ice crystals Surrounds the Earth Extends from the Earth’s surface to outer space

Permanent Atmospheric Gases Earth’s atmosphere consists mainly of nitrogen (78 percent) and oxygen (21 percent). The amounts of nitrogen and oxygen in the atmosphere are fairly constant over recent time.

Variable Atmospheric Gases The concentrations of some atmospheric gases are not as constant over time. The amount of water vapor, ozone, and carbon dioxide vary significantly from place to place.

Water Vapor (H 2 O(g)) Invisible, gaseous form of water Can range of 0% - 4% Concentration depends on the seasons, altitude, and properties of the surface underneath

Carbon Dioxide (CO 2) During the past 150 years, the concentration of atmospheric carbon dioxide has increased, due primarily to the burning of fossil fuels. Currently 0. 039% (up by 0. 028%)

Ozone (O 3) Mostly in ozone layer (20 – 50 km above) Only 0. 0012% but plays important role in blocking out harmful rays from the sun Concentration has decreased due to CFCs which are now banned Scientists estimate it should fully recover by the 2100

Atmosphere Particles Contains variable amounts of solids in the form of tiny particles, such as dust, salt, and ice Fungi and bacteria are often attached to these particles

Troposphere Closest to the Earth’s surface Contains most of the atmosphere’s mass Weather occurs in this layer Air temperature decreases with altitude Top is called tropopause

Stratosphere Above tropopause Contains the ozone layer Air temperature increases with altitude since the ozone layer absorbs the sun’s energy Ends at the stratopause

Mesosphere Above the stratopause Air temperature decreases with altitude since very little solar radiation is absorbed Ends at mesopause

Thermosphere Low air density so temperature rises (can be over 1000°C) Contains the ionosphere (made up of charged particles) Ends at thermopause

Exosphere Outermost layer Transitional region between the Earth’s atmosphere and outer space

Review of Thermal Energy and Heat Remember – all matter is made of particles in constant, random motion! These moving particles contain kinetic energy. The total kinetic energy of the moving particles is called thermal energy.

Review of Thermal Energy and Heat is the transfer of thermal energy from regions of higher temperature to regions of lower temperature

Energy Transfer in the Atmosphere In the atmosphere thermal energy is transferred by: Radiation Conduction Convection

Radiation Transfer of thermal energy by electromagnetic waves Thermal energy is transferred from the Sun to Earth by radiation

Absorption and Reflection Incoming solar radiation is either reflected back into space or absorbed by Earth’s atmosphere or its surface. 30% reflected 20% absorbed by atmosphere and clouds 50% absorbed by Earth’s surface

Rate of Absorption Depends on physical characteristics of the surface and the amount of solar radiation Examples – water heats and cools more slowly; dark colors absorb energy faster

Conduction Transfer of thermal energy when objects at two different temperatures are in contact Occurs between the Earth’s surface and lowest part of the atmosphere

Convection Remember – convection is the transfer of thermal energy by the movement of heated material from one place to another Near the Earth’s surface air becomes heated, expands, and rises then as it rises it cools, contracts, and sinks. This creates convection currents in the atmosphere.