Unit 10: The Atmosphere PDF

# Unit 10: The Atmosphere "You used to live just like the rest of the world, full of sin, obeying Satan, the mighty prince of the power of the air." - Ephesians 2:2 (NLT) ## Air - A Mixture of Gases Air is a mixture of gases. It contains all the gases we need to maintain life on earth. It also co...

# Unit 10: The Atmosphere "You used to live just like the rest of the world, full of sin, obeying Satan, the mighty prince of the power of the air." - Ephesians 2:2 (NLT) ## Air - A Mixture of Gases Air is a mixture of gases. It contains all the gases we need to maintain life on earth. It also contains several gases that are harmful to life called pollutants. ## Composition of Air | Substances | Percentage (%) | |---|---| | Nitrogen | ~78 | | Oxygen | ~21 | | Argon | ~0.93 | | Carbon dioxide | ~0.03 | | Other inert gases | Very small quantities (ppm) | | Water vapor | (~1%) varying quantities | | Pollutants (CO, SO2, NO2, H2S, soot) | varying quantities | ## Pollution Pollution is the contamination of the environment by substances that are harmful to life. Pollutants are substances that contaminate the environment. ### Why is pollution causing increasing concern to environmentalists? The formation of acid rain, contamination of the water tables and the buildup of non-biodegradable materials on the land-fill, are results of several irresponsible practices of mankind. The earth as God made it, is changing in many ways, because of increasing amounts of pollutants in the air, water and land. People have a variety of health problems that result from the pollution of the environment. In addition, the ozone layer is being depleted by harmful substances such as CFCs - chlorofluorocarbons. These are produced by refrigerators, aerosols and air conditioners. The ozone layer is important to protect life on earth from the harmful effects of ultraviolet rays coming from the sun. ## Photosynthesis and Respiration ### Photosynthesis (Photo means light; synthesis means building up) Photosynthesis is the process by which green plants manufacture glucose from carbon dioxide, water and light energy. The green pigment, chlorophyll is used to absorb sunlight. The equation for this reaction is as follows: Sunlight absorbed by Chlorophyll $6CO_2 + 6H_2O \longrightarrow C_6H_{12}O_6 + 6O_2$ ### Respiration Respiration is the process by which living organisms break down glucose in the presence of oxygen, releasing energy, carbon dioxide and water. The equation for this reaction is as follows: $6O_2 + C_6H_{12}O_6 \longrightarrow 6CO_2 + 6H_2O + 2880 kJ$ Photosynthesis is described as the chemical opposite of respiration. The products of photosynthesis are used as the reactants of respiration. The products of respiration are used as the reactants of photosynthesis. ## Air Pressure Air pressure is the weight of the air above a given place on earth. The weight is due to the pull of gravity on that air. Gravity is the force that pulls everything to the center of the Earth. The pressure of the air on earth decreases as we go further and further away from the earth's surface. The lightest gases like hydrogen and helium are furthest away from the earth's surface, and the heaviest ones like carbon dioxide, oxygen and nitrogen are closer to the earth's surface. Thus, air gets thinner and lighter as we go further away from the Earth's surface. ## Importance of Gases in Air * **Nitrogen** is used to make fertilizers and explosives. * **Oxygen** is used for respiration, supports burning and causes rusting. * **Carbon dioxide** is used: * for photosynthesis * to put out fires * to make dry ice * to help breads and cakes to rise * to add fizz to carbonated beverages * **Water vapor** is used: * to make rain clouds * to take part in many chemical reactions in the bodies of plants and animals * to transport essential materials around the bodies of plants and animals * to remove waste products from the bodies of plants and animals * **Neon** is used to make bright, colorful lights. When electricity flows through tubes filled with neon, the tube glows. * **Argon, Krypton and Xenon** are used to make light bulbs. They are used for this purpose because they do not react with the metals in these pieces of equipment even when they become very hot. * **Helium** is used to fill decorative balloons and weather balloons that carry apparatus for weather forecasting. This is because it is a very light gas. Helium is also mixed with oxygen, nitrogen and other gases, and used for deep-sea divers to breathe under water. This mixture is safer to breathe than pure oxygen. * **Hydrogen** is used to make margarine and fertilizers. There is no hydrogen in the air. Hydrogen exists beyond the space that we usually call air. ## A Barometer A barometer is an instrument used to measure air pressure. There are 2 types of barometers: * Mercury barometer * Aneroid barometer You will meet these barometers later in this textbook in "Unit 13: Weather". In that unit, you will see the diagrams of these barometers and how they work. ## The Atmosphere The atmosphere is a blanket of protective gases that covers the earth's surface, providing insulation against extreme temperatures. It extends beyond the space we usually call air (~700 miles or 1130 kilometres). The atmosphere is divided into 4 distinct layers and the exosphere. ### Diagram of the Layers of the Atmosphere | Layer | Height | | |---|---|---| | Exosphere | | | | Ionosphere | 480km | Long radio waves transmit information | | Mesosphere | | | | Stratosphere | 80km | | | Troposphere | 50km | | | | 10km | | | | | EARTH | * **Exosphere** - The outer part of the atmosphere, which extends into outer space. It has no outer limit. * **Ionosphere** - The layer of the atmosphere: * which is furthest from the earth. * in which the sun's energy strips off electrons from atoms forming ions. * which consists mainly of H and He (the lightest known elements). * in which the temperatures may go to a high of 1,250°C. It is the hottest layer. For this reason this layer is often called the thermosphere. * **Mesosphere** - The layer of the atmosphere: * that is in the middle of the atmosphere. * that is coldest (~-80°C). * **Stratosphere** - The layer of the atmosphere: * above the troposphere. * in which air flow is horizontal. * that has no water vapour and hence no clouds or storms. * in which large jets fly to avoid the "bad weather conditions in the troposphere. This causes turbulence during take-off. * that contains ozone which protects life on earth from the sun's harmful ultraviolet rays. * that has a temperature range of -55 to 0 °C. * **Troposphere** - the layer of the atmosphere: * that surrounds the earth. * in which most organisms live. * in which up and down air movements cause bad weather. * in which clouds, rain, snow and wind are found. * that contains almost all the water vapour and 80% of the air mass. This makes it the densest of the atmospheric layers. * that has an average temperature of 20 °C.