Name The Different Layers as they come in, also explain that the Exosphere is not really a layer but is the beginning of outer space.
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth’s gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention ( greenhouse effect ), and reducing temperature extremes between day and night.
Air is the name given to atmosphere used in breathing and photosynthesis. Composition of air
● ______ ● ______ ● ______ ● ______ The Atmosphere The temperature in the atmosphere varies depending on the different layer we are in.
<ul><li>Here, living things are also free from the radiation showers which flow down through most of the earth’s atmosphere. </li></ul><ul><li>Compared to the rest of the atmosphere, the troposphere is a tiny layer , extending at most 16km up from the earth’s surface. Within this small layer almost all of our weather is created. </li></ul>The Troposphere (I) <ul><li>It is the lowest level of earth’s atmosphere where the right mixture of oxygen and nitrogen works to support life. </li></ul>
<ul><li>Generally, as altitude increases, temperature decreases steadily. But the earth's topography—mountain ranges and plateaus—can cause some lower regions in the troposphere to experience temperature inversions. </li></ul>The Troposphere (II) <ul><li>Towards the top of the troposphere temperatures fall to an average low of -57 ºC and wind speeds increase significantly, making the top of the troposphere an extremely cold and windy place. </li></ul>
<ul><li>The gradual change from the troposphere to the stratosphere begins at approximately 11km high. The temperature in the lower stratosphere is extremely stable and cold at -57 ºC. </li></ul><ul><li>There are strong winds. High cirrus clouds sometimes form in the lower stratosphere, but for the most part there are no significant weather patterns in the stratosphere. </li></ul>The Stratosphere (I)
The Stratosphere (II) <ul><li>From the middle of the stratosphere and up, the temperature pattern undergoes a sudden change, sharply increasing with height. Much of this temperature change is due to increasing levels of ozone concentration which absorbs ultraviolet radiation. </li></ul><ul><li>The temperature can reach 18 ºC in the upper stratosphere near an altitude of 40km high. </li></ul>
<ul><li>40km above the earth’s surface marks the transition to the mesosphere. In this layer, temperature once again begins to fall as altitude increases, to temperatures as low as -143 ºC near its top, 81km above the earth. </li></ul>The Mesosphere <ul><li>Such extreme cold allows the formation of so-called noctilucent clouds, made of ice crystals clinging to dust particles. </li></ul>
<ul><li>It directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes ionization. </li></ul><ul><li>Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation by the small amount of residual oxygen still present. Temperatures can rise to 2,000°C. </li></ul>The Thermosphere <ul><li>Radiation causes the scattered air particles in this layer to become charged electrically enabling radio waves to bounce off and be </li></ul><ul><li>received beyond the horizon. </li></ul>
<ul><li>The exosphere is the uppermost layer of the atmosphere. </li></ul><ul><li>In the exosphere, an upward travelling molecule moving fast enough to attain escape velocity can escape to space; if it is moving below escape velocity it will be prevented from escaping by gravity. </li></ul>The Exosphere
Since part of this re-radiation is back towards the surface, energy is transferred to the surface and the lower atmosphere. As a result, the temperature there is higher than it would be if direct heating by solar radiation were the only warming mechanism. The greenhouse effect is a process by which radiation from the surface of the Earth is absorbed by atmospheric gases, and is re-radiated in all directions.