Published on December 1, 2009
ATMOSPHERIC LAYERS : ATMOSPHERIC LAYERS Slide 2: What gases are found in the atmosphere? Nitrogen, Oxygen, Water Vapour, Carbon Dioxide, Ozone, Other gases Why is the earth divided into four layers? Because of the change in air temperature! THE TROPOSPHERE : THE TROPOSPHERE It is the most important layer for living things because it contains over 80% of all the air in the atmosphere! It contains almost all the water vapour in the atmosphere, and water vapour produces weather (like rain and clouds) and determines climate Average temperature: drops 6% with each kilometer of altitude. Varies in thickness and temperature THE STRATOSPHERE : THE STRATOSPHERE Approximately 40km thick Located just above troposphere Large planes travel through this layer, just above cloud layer? DO YOU KNOW WHY? Because air is thinner at this altitude and so planes encounter less friction there and can therefore fly faster and use less fuel. Slide 7: The ozone layer is found there. WHAT IS THE OZONE LAYER? It is a layer of gas that absorbs the ultraviolet rays coming from the sun. It protects us from these rays, which cause skin cancer. The ultraviolet rays heat the atmosphere, the farther from earth the higher the temperature. THE MESOSPHERE : THE MESOSPHERE It is the third layer of the atmosphere It is approximately 40km thick. There is a wide variety of temperatures because there aren’t many air molecules and so they do not absorb a lot of warmth from the sun. (Minimun= -120 degrees Celsius, Maximum from 0-27 degrees Celsius) Slide 10: What does this layer protect us from? It protects Earth from meteoroids that have manages to break through the Thermosphere. This is because when the meteoroids come into contact with air molecules the friction heats them and they catch fire and break! THE THERMOSPHERE : THE THERMOSPHERE The fourth and last layer The thickest layer Measures over 90km Sun’s rays are strong in this zone, and create high temperatures that exceed 1000 degrees celcius. Slide 13: At an altitude of 90 to 300km the IONOSPHERE is found. It is useful from earth’s communication system because it contains a lot of electrically charged particles. These particles bounce radio waves. Most meteoroids heading towards Earth are burnt in this layer. CAN WE SEE THESE METEOROIDS FROM EARTH? YES…. We see them as shooting stars!!! The polar auroras are also found in this layer! A HOLE IN THE OZONE LAYER : A HOLE IN THE OZONE LAYER The thickness of the Ozone Layer is shrinking because of CFC’s (Chloroflurocarbons) and aerosol products. Why would the thinning of the ozone layer worry us? Because it protects us from UV rays. It can increase skin cancer. If the ozone increases at low altitudes (like the troposphere) it can also cause health problems. The increase in ozone at low altitudes is caused by pollution.