Atmosphere
    The earth�s atmosphere is vital to life on our planet. It provides us with a livable climate, and �protects us from high-energy radiation and the frigid vacuum of space.� (nasa.gov). The atmosphere is made up of four layers: the troposphere, the stratosphere, the mesosphere and the thermosphere.
     The troposphere, known as the lower atmosphere, begins at the surface of the earth and is approximately five to nine miles high. As altitude increases, the temperature decreases. This is the densest layer of the atmosphere. The troposphere is also the part of the atmosphere where all weather and clouds occur; from this, one can infer that this layer is where most of the water vapor is held.  
     The stratosphere is the next layer of the atmosphere, extending from the top of the troposphere to about 31 miles high from the surface of the earth. This layer is drier and less dense than the troposphere, and does not contain any clouds. The ozone, a form of oxygen, is located in the stratosphere, and absorbs solar radiation. When halogen source gases, containing chlorine or bromine, (which I have not discussed), build up in the atmosphere, they have a depleting effect on the ozone. This can contribute to the effects of global warming because there is less ozone to absorb incoming solar radiation, which results in greater incoming heat.
     The mesosphere is the third atmospheric layer, which stretches from the top of the stratosphere to about 53 miles high. As altitude increases, temperatures decrease to as low as -93� C. Together with the stratosphere, the mesosphere makes up the middle atmosphere.
The fourth and last layer of the atmosphere is the thermosphere, also known as the upper atmosphere. This layer reaches about 372 miles high. As altitude increases, temperature increases. Energy from the sun can heat this layer up to 1727� C.

     Nitrogen and oxygen are the primary components of the atmosphere, with nitrogen making up 78% and oxygen making up 21% of it. The rest of the atmosphere is composed of trace amounts of several other gases � greenhouse gases. These gases, however, are responsible for regulating the earth�s climate. Since the beginning of the Industrial Revolution, levels of greenhouse gases in the atmosphere have been rising.
"Let's start with the year 1750, generally accepted as the beginning of the Industrial Revolution, when the standard measure for CO2 levels was 278ppmv. We'll begin then, add the known level of human-generated CO2 for that year, then subtract 2.84% of the excess CO2 � because that's how fast nature tries to restore the balance. If we do this for 255 years, up to 2005, we get the pink line in the graph below. It fits the black line � the actual CO2 level � like a glove."
                                                                                   - http://zfacts.com/p/194.html
As you can see from this graph from www.landcareresearch.co.nz, methane levels have been steadily increasing since about 1800 - right around the beginning of the industrial revolution.
Chem X Home Next Page -->
Effects Main Page
Hosted by www.Geocities.ws

1