Pour me a heavy dose of ATMOSPHERE.

Hello class! I think you all need a recap of what we learnt last term (i.e. IS2104 Tutorial 2, 15 January 2010, haha). So let's rewind to 3 months ago, when we did not have the TC block classroom, when we were not boarding, when the weather was not so hot.

Your mind should now think that it is now 15 January 2010.

Today, we went through the answers for the 'Layers of the Atmosphere' worksheet that we were given. During the previous lesson, we were told to plot the graph to identify the different layers of the Earth's atmosphere with respect to the altitude and the temperature. We then found out that the basis for dividing the atmosphere is due to the different temperature changes. From the graph, we can tell how each layer's temperature varies with how far the layer is away from the Earth. We have learnt that:

• Troposphere, 17 km, -60°C, decreases with altitude: As the density of the gases in this layer decreases with height, the air thins. The heat that hits the Earth's surface gets reflected upward and converted into heat. Therefore, the higher you go in the troposphere, the colder it is, until you hit the ozone layer in the stratosphere.
• Stratosphere, 50 km, -2°C, increases with altitude: The increase is caused by the ozone layer capturing and absorbing ultraviolet radiation by the sun.
  
• Mesosphere, 80 km, -90°C, decreases with altitude: The amount of air decreases, and there is no ozone, and thus the temperature decreases. In fact, the mesosphere is the coldest layer of the atmosphere, dropping to a temperature of -90C.
• Thermosphere, 690 km, 2,000°C, increases with altitude: There are very few molecules present in the thermosphere, and thus they receive large amounts of heat energy from the sun, causing the layer to warm to such a high temperature. Air temperature, however, is a measure of the kinetic energy of air molecules, not of the total energy stored by the air. Therefore, since the air is so thin within the thermosphere, such temperature values are not comparable to those of the troposphere or stratosphere. Although the measured temperature is very high, the thermosphere would feel cold to us because of the small energy of only a few air molecules residing there to transfer any heat to our skin.

So the shape of the graph on page 3 of the worksheet should look something like this:


Yup that was all that we learnt for this lesson, hope this entry helped you understand more about our atmosphere!

Okay you can now think that it is 24 April 2010.

Adelia Ng (01)