The Atmosphere - Grade 10 Geography (PDF)

THE ATMOSPHERE G E O G RA P H Y Grade 10- TOPIC 2 ON TODAY'S Introduction. AGENDA: The structure of the atmosphere. Activities! INTRODUCTION: What you will learn in this topic: What is the atmosphere? How important the atmosphere is to life on Earth. Composition of th...

THE ATMOSPHERE G E O G RA P H Y Grade 10- TOPIC 2 ON TODAY'S Introduction. AGENDA: The structure of the atmosphere. Activities! INTRODUCTION: What you will learn in this topic: What is the atmosphere? How important the atmosphere is to life on Earth. Composition of the atmosphere. Structure of the atmosphere. Weather processes that takes place in the atmosphere. Factors that affect weather and climate What is global warming? What is climate change? Impact of global warming and climate change on Africa. COMPOSITION OF THE ATMOSPHERE:  THE ATMOSPHERE It is the layer of gases that surrounds the Earth. THE STRUCTURE, COMPOSITION AND IMPORTANCE OF THE ATMOSPHERE UNIT 1: PAGE 82 THE STRUCTURE OF THE AT M O S P H E R E The atmosphere consists out of four layers. Thermosphere Mesosphere Stratosphere Troposphere  1.THERMOSPHERE The thermosphere is the layer furthest away from the earth. Extends about from 85-120 km They layer absorbs many of the sun's harmful X-rays and ultraviolet rays. Therefore, this layer consists out of high temperatures ⚬ and increases in distance the further away from the Earth. ⚬ from 500- 2000 ºC or higher.  1.THERMOSPHERE Boundary between the Thermosphere and Exosphere – Thermopause. Air density is very low- most of the thermosphere is what we know as outer space. Space "begins" at altitude of 100 km. Space shuttle and the International Space Station both  2.MESOSPHERE Lies below the Thermosphere and above the Stratosphere. Extends about from 50 - 85 km. The boundary between the Mesosphere and thermosphere is called the Mesopause. This layer consists out of coldest temperatures in earth's atmosphere, about -90 ºC.  2.MESOSPHERE Prevents dust and rocks from entering the lower layers of the atmosphere. Meteors vaporize in this layer. Some parts of the meteors linger in this layer - high concentration of iron. Mesosphere and Stratosphere together -middle of the atmosphere  3. S T RAT O S P H E R E Second layer above the Earth's surface and lies below the mesosphere. It contains a layer of ozone O3 - gas which absorbs ultraviolet rays from the sun. The ozone layer can be found in the Stratosphere. ⚬ Ozone layer: is a shield or region of Earth's stratosphere that absorbs most of the Sun's  3. S T RAT O S P H E R E Stratosphere extends about from 10 -50 km- The upper boundary is called the Stratopause, and the lower boundary of the stratosphere is called the Tropopause. Layer varies in latitude and seasons. The stratosphere is very dry; air there contains little water vapor, because of this, few clouds are found in this layer. Commercial jet aircraft fly in the lower stratosphere - to avoid the turbulence which is common in the troposphere below.  4.TROPOSPHERE The layer the closest to the Earth's surface. Layer is approximately 8 km thick at the poles and 17 km thick at the equator. This layer contains most of the air of the atmosphere. Contains gases which are essential to life. Most of the mass (about 75-80%) of the atmosphere is in the troposphere. Most types of clouds are found in the troposphere The behaviour of the air in the troposphere leads to weather. The troposphere extends upward to about 10  4.TROPOSPHERE The height of the top of the troposphere varies with latitude and by season, it can be as high as 20 km. Air is warmest at the bottom of the troposphere near ground level. Air gets colder as one rises through the troposphere. That's why the peaks of tall mountains can be snow-covered even in the summertime. Air pressure and the density of the air also decrease with altitude. The boundary between the troposphere and the stratosphere is called the Tropopause. Aircraft and Hot-air balloons fly in this layer.  THE STRUCTURE OF T Hfactor The E AT that M O S P Hone distinguishes ERE layer from the next is the temperature change. Look at figure 2.4 shows us that in the troposphere, the temperature decreases as height above the Earth's surface increases, ⚬ Tropopause the temperature starts to increase as height above the Earth’s surface increases. So, in conclusion, in the Troposphere it becomes colder the higher we go, in the stratosphere it becomes warmer as we go HOMEWORK Ke y w o rd s p a g e 8 2 - 8 3 Ac t i v i t y 1 , p a g e 8 1 n o. 1 - 4 Ac t i v i t y 2 , p a g e 8 3 THE STRUCTURE, COMPOSITION AND IMPORTANCE OF THE ATMOSPHERE UNIT 1: PAGE 82  ON TODAY'S The composition of the atmosphere. AGENDA: The importance of the atmosphere. The ozone layer. Causes of the ozone depletion. Effects of ozone depletion. Reducing ozone depletion. Activity! COMPOSITION OF THE AT MO The S P H E Ris Emade up of gases. solids and liquid. atmosphere These substances are essential for life on Earth! Gases: The troposphere is a mixture of gases. Gases are permanent and in fixed proportions while others exit in varying amounts. The amount of gases decreases as the distance from the surfaces of the Earth increases - the further away from the Earth, the smaller amount of gases in the atmosphere.  COMPOSITION OF THE AT M O S P H E R E Permanent gases in the atmosphere are: Argo Nitrogen 78% - this element is necessary n 1% for the growth of plants. Oxyge n Oxygen 21% - this element is necessary 21% for respiration. Argon 1% of the gases in the gases in the atmosphere are gases which exist in variable amounts such as; ⚬ carbon dioxide, helium, ozone, water vapour, carbon monoxide, methane, nitrous oxide and sulphur dioxide. Nitroge n Some of these gasses are called- greenhouse 78% gases.  COMPOSITION OF THE AT M O S P H E R E Solids: There are millions of minute, ⚬ solid dust particles ⚬ and salt crystals in the air. Water vapour condenses on these. Liquid: The atmosphere also contains water - in the form of clouds. WHY THE ATMOSPHERE IS IMPORTANT It is important to look after our Atmosphere, because the atmosphere is essential for life on earth! Without the atmosphere, gases such as ⚬ oxygen, ⚬ carbon dioxide ⚬ and water vapour would not exist- which is necessary for life on Earth. Harmful rays from the sun would strike Earth. Our planet would be a desert, baked by the sun during the day and frozen at night.  WHY THE ATMOSPHERE IS IMPORTANT Atmosphere is essential for the following reasons: The properties of the lower layer of the atmosphere allow us to experience different weather conditions and climate. ⚬ Gases like carbon dioxide and water vapour absorb some of the energy that the sun radiates - thus, air becomes warmer and the atmosphere moves. ⚬ Wind transports hot air, cold air and moisture to different parts of the globe. Some layers of the atmosphere absorb dangerous radiation from the sun; ⚬ X-rays  WHY THE ATMOSPHERE IS IMPORTANT Atmosphere is essential for the following reasons: The atmosphere acts as a blanket around the Earth. It protects us from extremely high temperatures during the day, prevents heat from escaping at night. The gases in the lower layer of the atmosphere are necessary for life on Earth. All life forms need; ⚬ oxygen for respiration. (Respiration: the action to breath) ⚬ plants need carbon dioxide and nitrogen in order to grow ⚬ and water vapour provides the moisture that plants an animals need. THE OZONE LAYER IN THE STRATOSPHERE UNIT 2: PAGE 85 THE OZONE LAYER IN THE STRATOSPHERE: Ozone layer: layer of gas in the stratosphere that is very important in helping protect the Earth from the sun's harmful radiation.  THE OZONE LAYER: Ozone: is a form of oxygen which is blue in colour. The ozone molecule consists of three oxygen atoms - O3. Figure 2.7- shows how ozone forms. ⚬ When the ultraviolet rays strike molecules of oxygen O2. it splits them into two single oxygen atoms. An oxygen atom then combines with an oxygen molecule to form a molecule of ozone O3. O Absorbs UV O rays O2 UV rays from combines with Splits sun O2 OZONE IN THE EARTH'S ATMOSPHERE: Stratosphere: Ozone is 'good' because it protects the Earth from the sun's harmful UV radiation. Troposphere: Ozone is 'bad' because it is a greenhouse gas and a pollutant. Mesosphere  CAUSES OF OZONE D ofEcertain PLETION Human activity has caused the depletion of the ozone layer in the Stratosphere. The use aerosol sprays refrigerants air conditioners industrial cleaning materials releases chlorofluorocarbons (CFCs) into the atmosphere. Chlorofluorocarbons = chemicals. The CFCs rise and collect in the Stratosphere, they then release chlorine. The chlorine destroys ozone and splits the ozone molecules back into oxygen molecules (O2) and oxygen atoms (O).  OZONE DEPLETION: O 2 Ozone is Chlorine in O destroyed CFCs O3 Splits This process leads to ozone depletion as the ozone layer becomes thinner. Eventually, holes form in ozone layer. Look at Figure 2.10.  EFFECTS OF OZONE DEPLETION: Later in Unit 6 we will talk about how ozone in the Troposphere contributes to global warming. However, it is important to remember how important ozone is in the Stratosphere. Ozone depletion: destruction of ozone so that holes are form in the ozone layer. The depletion of ozone in the stratosphere is leading to more of the sun's dangerous ultraviolet radiation entering the troposphere, where holes have formed in the ozone layer. Look at figure 2.11.  ozone in both EFFECTS OF OZONE layers DEPLETION: UV rays reflecting back off the protective ozone layer UV rays Sun CFC s Troposphere Dangerous UV rays entering through the Stratosphere ozone holes  EFFECTS OF OZONE DEPLETION: Ultraviolet radiation in the troposphere can affect people in the following ways: People's eyes, cataracts may develop = results in blurred vision and eventually blindness Faster ageing skin = sooner wrinkles, as well as lead to skin cancer. Weaken immune system = body can not fight disease. Ultraviolet radiation can affect the environment: Disrupt photosynthesis = leads to lower crop yields.  REDUCING OF OZONE DEPLETION: Understanding how the release of CFCs through human activity leads to ozone depletion. Countries agreed to phase out the use of CFCs by 1996 - signing an international agreement called the Montreal Protocol on 16th September 1987. Since then the 16th of September has been the International Day of the Preservation of the Ozone Layer. In order to phase out CFC's, scientists found effective substitutes for nearly all the ozone-depleting chemicals, thus CFCs are no longer produced. Halocarbons have replaced CFCs. Aerosol cans = labeled  REDUCING OF OZONE DEPLETION: Developing countries did not have the technology or money to pay for the substitutes - rich industrialised countries stepped in and helped. However, it will take many years for the atmosphere to restore its natural balance, due to the CFCs remaining in the atmosphere for about 100 years. Indications that the hole in the Ozone layer will continue to grow for some time. HOMEWORK Ke y w o rd s p a g e 8 4 - 8 6 Ac t i v i t y 3 , p a g e 8 4 n o. 1 - 2 Ac t i v i t y 4 , p a g e 8 7 n o. 1 - 4 HEATING OF THE ATMOSPHERE: ON TODAY'S Processes associated with AGENDA: heating of the atmosphere. The sun’s electromagnetic spectrum Insolation. Activity! PROCESSES ASSOCIATED WITH HEATING OF THE ATMOSPHERE UNIT 3: PAGE 88 HOW RADIATION HEATS THE ATMOSPHERE: The sun is a source of energy for heating the atmosphere, it is mainly the Earth that heats the atmosphere! Radiation from the sun passes through the atmosphere and then the Earth’s surface absorbs this radiation, becomes warmer and then heats the atmosphere. Short-wave radiation heats the Earth's surface. Long-wave radiation from Earth heats the atmosphere. VIDEO:  THE SUN'S ELECTROMAGNETIC SPECTRUM: The sun transmits energy (invisibly) in the form of waves - this is called radiant energy. Radiant energy is radiated in different wavelengths. Wavelength: the distance from crest to crest of two waves. Crest: the peak or highest point of a wave. Wavelength Crest Crest ELECTROMAGNETIC SPECTRUM: Electromagnetic spectrum (EM): is a diagram that shows the range of all types of radiation. Radiation: the emission of energy as electromagnetic waves. ⚬ Visible light from a lamp and the waves of a radio are two types of EM  THE SUN'S ELECTROMAGNETIC SPECTRUM: Electromagnetic spectrum of the sun (EM): the distribution of the sun's radiation according to wavelength X-rays have a shorter wavelength and Infrared waves have a longer wavelength. Light waves are the only waves that are visible. And the wavelength falls in the middle of the spectrum.  THE SUN'S ELECTROMAGNETIC SPECTRUM: Look at figure 2.14 - shows the different wavelengths of the spectrum.  INSOLATION: Insolation: Incoming radiation from the sun. The sun's energy that passes through the Earth's atmosphere from incoming solar radiation. The sun emits ⚬ short-wave ⚬ and long-wave radiation. Most of the ultraviolet rays and X-rays are absorbed in the Thermosphere and Stratosphere = therefore the temperatures are so high in these layers. Solar constant: the amount of solar radiation that reaches the Tropopause. THE PASSAGE OF THE SUN'S ENERGY THROUGH THE TROPOSPHERE: Solar One billionth of the sun's constant radiant energy reaches the tropopause Stratosphere Absorption by Scattering by CO2 and water air and dust vapour Reflection off Reflection off surfaces 47% of the clouds Tropopause solar constant reaches Earth's surface Earth's Troposphere REFLECTION, SCATTERING AND ABSORPTION OF THE ENERGY THAT THE SUN RADIATES: 53% of the sun's radiation which reaches the tropopause the tropopause does not reach the Earth's surface, because: Surfaces reflect or send some radiation back into the upper atmosphere before it is absorbed. Absorbed: gases in the atmosphere take in radiation. Reflection: radiation strikes a surface, but is sent back into the atmosphere without being absorbed. Surfaces have different properties of reflection. ⚬ Snow and ice are good reflectors. ⚬ Soil and paving are poor reflectors of insolation. PROCESSES ASSOCIATED WITH HEATING OF THE ATMOSPHERE UNIT 3: PAGE 88 REFLECTION, SCATTERING AND ABSORPTION OF THE ENERGY THAT THE SUN RADIATES: Gases in the troposphere absorb some radiation - absorption Some radiation is bounced off dust particles - Scattering. Only 47% of the Sun's energy which reaches the tropopause also reaches the surface of the Earth. The energy that reaches the Earth's surface is in the form of short- wave radiation that the atmosphere is not able to absorb. This energy then heats the Earth's surface. HEATING OF THE ATMOSPHERE BY THE EARTH: The sun's energy warms the Earth's surface. All the heat which the Earth's surface receives from the sun is transferred back into back into the atmosphere on order to maintain heat balance. Heat balance: The earth radiates the same amount of energy it receives from the sun. The Earth heats the atmosphere in four different ways; ⚬ radiation, conduction, convection and the release of latent heat. Figure 2.17 1. RADIATION BY THE EARTH: Terrestrial refers to the Earth. The heat energy that the Earth radiates - called Terrestrial radiation. The Earth has a much lower temperature than the sun and therefore radiates heat energy in long waves. Water vapour and gases, such as carbon dioxide = absorb the long-wave terrestrial radiation. Because water vapour and carbon dioxide are more concentrated close to the Earth's surface, more absorption takes place. At the Earth's surface the air is warmer - thus temperatures decrease as the height above the Earth's surfaces increase. Terrestrial radiation happens mainly at night. Because clouds act as a blanket because they prevent terrestrial radiation from escaping into space. 2. CONDUCTION: Conduction: is the transfer of heat energy from one air molecule to another by contact. (Transfer of heat by contact) Air is a poor conductor of heat, contact with the Earth's surface heats only the lowest layers of the atmosphere. Example: pan warming on the stove. 3. CONVECTION: Convection: is the vertical transfer of heat energy by movement of air molecules. The hot air in the lower air expands, becomes light and rises. Hot air is transferred to higher altitudes. (Warm air rises/ less dense - Cold air sinks/ more dense)  4. RELEASE OF LATENT HEAT: Heat is also transferred when condensation occurs. The Heat that is used in the process of evaporation is stored in the water vapour as latent or hidden heat. When the air rises and cools, condensation of water vapour occurs, and this releases the latent heat. Latent heat: hidden heat energy used in changing the state of a body; ⚬ example, during evaporation when water changes from liquid to a gas. Look at the case study on page 92. Energy drawn by Mother Nature. HOMEWORK Ac t i v i t y 5 , p a g e 9 0 n o. 1 - 4 Ac t i v i t y 6 , p a g e 9 1 n o. 1 - 4 Ac t i v i t y 7 , p a g e 9 2 n o. 1 - 4 THE GREENHOUSE EFFECT UNIT 4: PAGE 93 ON TODAY'S The greenhouse effect. AGENDA: How a greenhouse work. Impact of greenhouse effect. Deforestation. Activity!  THE GREENHOUSE E F F E C T: A greenhouse is a glass house that people use for growing plants. The air inside a greenhouse remains warm because it traps heat - this means people can grow plants in the greenhouse even if it is cold outside.  Short HOW A Glass traps waves move GREENHOUSE long waves through glass. WORKS: Greenhouse gas: CO2, CFC. Short-wave radiation enters the greenhouse and The long-wave radiation trapped inside the greenhouse.  T H E G R E E N H O U S E E F F E C T: The atmosphere allows short-wave of insolation to move through the atmosphere and heat the surface of the Earth. But, different from the greenhouse, the atmosphere absorbs the long-wave of insolation and terrestrial radiation. This traps heat and keeps it in the lower layer of the atmosphere. The gases that absorb and trap the long-wave radiation - called Greenhouse gases. Greenhouse gasses are mostly water vapour and carbon dioxide, but other pollution gases also absorb long-wave  THE GREENHOUSE EFFECT CO2 and water vapour absorb long-wave radiation = they keep the atmosphere warm, and heat is radiated back to Earth. CO2 CO2 Warm Warm Water Water vapour vapour Water Water CO2 CO2 vapour vapour Warm Warm Earth Earth Atmospher Atmospher T H E G R E E N H O U S E E F F E C T: The natural greenhouse effect of the atmosphere keeps the Earth's temperature about 15ºC higher than it would be. Importance of the greenhouse effect: Without the greenhouse effect of the atmosphere, nights would be bitterly cold. The greenhouse effect is necessary to sustain life on Earth. People, animals and other organisms would not survive. Vegetation would not grow = no food.  I M PAC T O F T H E G R E E N H O U S E EFFECT ON PEOPLE AND THE E N V I R O N M E N T: People have been adding excessive amounts of greenhouse gases to the atmosphere. This is enhancing the greenhouse effect and causing temperatures to become higher. The higher the concentration of greenhouse gases, the more heat energy the atmosphere absorbs and reflects back to Earth = Global warming. Scientist believe that global warming can result in the change of climate of the world.  I M PAC T O F T H E G R E E N H O U S E EFFECT ON PEOPLE AND THE E N V I R O N M E N T: Smog: pollution and smoke combined with fog  D E F O R E S TAT I ON: Deforestation: the removal of trees increases the amount of carbon dioxide in the atmosphere, Trees absorb carbon dioxide in the process of the photosynthesis.  THE INCREASE IN GREENHOUSE GASES = MAJOR Higher temperatures P Raffect will O Bthe LE M S : in the following environment ways: Changes to habitats of animals. Extinction of species that cannot adapt to change. Melting of permanent ice and rising sea levels. changes in weather patterns and climates. Droughts, fires and floods. Global warming will force people to move to places where there is enough food and water.  THE INCREASE IN GREENHOUSE GASES = MAJOR PR The enhanced greenhouse OB effect andL E M Sclimates changing : can also lead to various health problems: HOMEWORK Ac t i v i t y 8 , p a g e 9 5 n o. 1 - 2