THE ATMOSPHERE OF THE EARTH Components Molecular Variation Pressure Variation Energy Balance Temperature Variation Layers
Components of the Atmosphere • Through all the layers, the composition of the atmosphere is about the same. • Each component has important uses and roles for our planet. • Each component cycles in and out of the atmosphere.
Atmospheric Components Cycle through the Atmosphere Nitrogen cycles through the atmosphere. Carbon, oxygen, and carbon dioxide cycle through the atmosphere.
ATMOSPHERIC PRESSURE • Because of gravity, most of the molecules that make up the gasses of the atmosphere collect at the lowest levels. • Half of the molecules in the atmosphere exist below the 5 km level. • Weather occurs at levels below 10 km.
ENERGY BALANCE Energy is radiated from the earth at the same rate that it is received. If not, the earth would be getting hotter and hotter. The upper atmosphere is warmed by the sun, so it is hotter as the altitude increases. The lower atmosphere is heated by energy being radiated from the earth’s surface, so that as the altitude increases, the temperature decreases. Incoming Energy Outgoing Energy
ATMOSPHERIC TEMPERATURE • Notice that temperature follows several patterns in the atmosphere. • The upper atmosphere is warmed by the sun, so it is hotter as the altitude increases. • The lower atmosphere is heated by energy being radiated from the earth’s surface, so that as the altitude increases, the temperature decreases.
ATMOSPHERIC LAYERS: TROPOSPHERE • This is the lowest layer of the atmosphere and the layer in which you live. • Almost all weather takes place in the troposphere. • The troposphere is heated by energy being radiated from the earth’s surface, so that as the altitude increases, the temperature decreases. • Most of the molecules of the atmosphere are found in the troposphere.
ATMOSPHERIC LAYERS: STRATOSPHERE • The stratosphere is the layer in which jets most often travel. • It is clear (clouds are found in the troposphere) and cold. • The ozone layer is found in the stratosphere. The warming that occurs in the upper part of the stratosphere happens because cosmic rays are absorbed by ozone, adding energy (heat) and making chemical changes. • Pollution in this layer does not migrate or mix.
ATMOSPHERIC LAYERS: MESOSPHERE • The mesosphere and stratosphere both contain a special form of oxygen called ozone. • Ozone filters out powerful ultraviolet rays from the sun, without which, life would be difficult on our planet. • This zone has the coldest temperatures in the atmosphere.
ATMOSPHERIC LAYERS: THERMOSPHERE • Temperatures rise rapidly in the thermosphere because high energy x-rays are being absorbed. • The thermosphere extends as high as 600 km, and temperatures can go as high as 2000 F. • The high temperatures found at this level would not really cause an object to get hot, because there is really on one ten millionth of the density of air as at the earth’s surface.
Layers of the Atmosphere: Ionophere and Magnetosphere • The ionosphere is named for the ions it contains. These are charged particles that result from powerful cosmic rays that collide with the atoms of the atmosphere. High energy particles strip electrons from the atoms of oxygen and nitrogen. The ionosphere is important for long-distance radio communications by reflecting radio signals. By repeated bouncing, a radio signal can travel completely around the globe. An aurora is triggered by the solar wind, a stream of charged particles that come from the sun. The earth’s magnetic field deflects the solar wind and as a consequence form the teardrop shaped zone known as the magnetosphere. The interaction between solar wind and magnetosphere produces the Northern lights. Nitrogen ions produce pink and magenta light whereas charged oxygen ions emit greenish light.