{"id":25243,"date":"2018-06-02T10:37:38","date_gmt":"2018-06-02T10:37:38","guid":{"rendered":"https:\/\/www.aplustopper.com\/?p=25243"},"modified":"2020-10-16T17:18:42","modified_gmt":"2020-10-16T11:48:42","slug":"icse-solutions-for-class-9-geography-composition-and-structure-of-the-atmosphere","status":"publish","type":"post","link":"https:\/\/www.aplustopper.com\/icse-solutions-for-class-9-geography-composition-and-structure-of-the-atmosphere\/","title":{"rendered":"ICSE Solutions for Class 9 Geography – Composition and Structure of the Atmosphere"},"content":{"rendered":"
ICSE Solutions<\/a>Selina ICSE Solutions<\/a>ML Aggarwal Solutions<\/a><\/p>\n Exercises<\/strong><\/span><\/p>\n I. Short Answer Questions.<\/strong><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Question 4.<\/strong><\/span> Question 5.<\/strong><\/span> Question 6.<\/strong><\/span> Question 7.<\/strong><\/span> Question 8.<\/strong><\/span> Question 9.<\/strong><\/span> Question 10.<\/strong><\/span> Question 11.<\/strong><\/span> Question 12.<\/strong><\/span> Question 13.<\/strong><\/span> Question 14.<\/strong><\/span> Question 15.<\/strong><\/span> II. Explain the following terms\/processes in detail<\/strong><\/p>\n Answer:<\/strong><\/span><\/p>\n III. Long Answer Questions<\/strong><\/p>\n Question 1.<\/strong><\/span> Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Question 4.<\/strong><\/span> Question 5.<\/strong><\/span> Question 6.<\/strong><\/span> Practice Questions (Solved)<\/strong><\/span><\/p>\n Question 1.<\/strong><\/span><\/p>\n (a)<\/strong> What is \u2018Atmosphere\u2019 ? Answer:<\/strong><\/span><\/p>\n (a)<\/strong> The earth is surrounded by a coverage of air which extends to height of several hundred kilometres. This is called the atmosphere. Near the surface of the earth, the air is dense, as we go up higher, the atmosphere gets more and more rare field. About half the air composing the atmosphere is found within 5 kilometres of the earth surface. Question 2.<\/strong><\/span> Question 3.<\/strong><\/span> Effects of Global Warming :<\/strong> Global warming can cause changes in rainfall patterns leading to flooding in some areas and drought in others. Monsoon flooding is expected to cause great loss of life in India, Bangladesh and South-East Asian countries. Over the last 100 years, because of Global Warming, the ice reserves have melted and the sea level has risen by about 10 to 25 cm. If this trend continues, areas will be submerged under sea water.<\/p>\n Question 4.<\/strong><\/span> (a)<\/strong> Ozone hole Answer:<\/strong><\/span><\/p>\n (a) Ozone hole :<\/strong> The large depletion of ozone layer in certain parts of the atmosphere is called Ozone hole. Question 5.<\/strong><\/span> Question 6.<\/strong><\/span> Question 7.<\/strong><\/span> Properties of Ionosphere :<\/strong><\/p>\n Question 8.<\/strong><\/span>
\nWhat is known as atmosphere ?
\nAnswer:<\/strong><\/span>
\nThe blanket of air upto 1500 km surrounding the earth is known as atmosphere.<\/p>\n
\nState the gaseous composition of the atmosphere.
\nAnswer:<\/strong><\/span>
\nThe atmosphere consists of 78% Nitrogen 21% oxygen and 1% other gases.<\/p>\n
\nMention any three functions of the atmosphere.
\nAnswer:<\/strong><\/span><\/p>\n\n
\nName the four layers of the atmosphere.
\nAnswer:<\/strong><\/span>
\nFour layers of the atmosphere are :<\/strong><\/p>\n\n
\nWhat is known as troposphere ?
\nAnswer:<\/strong><\/span>
\nTroposphere is the lowest and densest layer of atmosphere touching the land surface. It extends from 8km to 18 km. in height<\/p>\n
\nMention the chief characteristics of stratosphere.
\nAnswer:<\/strong><\/span>
\nThere is total absence of water vapour in this layer. It extends upto a height of 50 km. The temperature remains constant up to – 55\u00b0C.<\/p>\n
\nIn which layer of atmosphere do all weather conditions occur ?
\nAnswer:<\/strong><\/span>
\nTroposphere is the layer where all weather conditions occur in different forms.<\/p>\n
\nName the constituent gases of atmosphere which scientists consider responsible for climate change.
\nAnswer:<\/strong><\/span>
\nCarbon dioxide and ozone are responsible for climate change, as carbon dioxide absorbs heat from sun and by radiation from the earth; ozone absorbs extremely hot ultra-violet rays controlling the ideal temperature conditions on the earth.<\/p>\n
\nWhat is known as ozone layer ?
\nAnswer:<\/strong><\/span>
\nStratosphere contains sufficient amount of ozone which absorbs the extremely hot ultra-violet rays of the sun. It is known as ozone layer.<\/p>\n
\nWhat is leading to depletion of ozone layer in the atmosphere ?
\nAnswer:<\/strong><\/span>
\nExcessive emission of carbon monoxide and CFCs from industries and vehicles take out the oxygen from ozone layer to form different compounds (oxides). In this way the depletion of ozone layer takes place.<\/p>\n
\nWhat is known as Global Warming?
\nAnswer:<\/strong><\/span>
\nGlobal Warming is the increase in temperature of earth due to enhanced concentration of Greenhouse gases (CFCs) in the atmosphere.<\/p>\n
\nName important Greenhouse gases.
\nAnswer:<\/strong><\/span>
\nThe main Greenhouse gases are CFCs (Chlorofluorocarbons) and nitrogen oxides which are emitted by fertilizers industries and transport engines along with carbon dioxide and methane.<\/p>\n
\nName two chief characteristics of atmosphere.
\nAnswer:<\/strong><\/span>
\nAtmosphere protects earth from harmful ultra-violet and infra-red rays of the sun. It controls the hydrological cycle and provide life giving gases.<\/p>\n
\nWhat keeps the atmosphere in a dynamic state ?
\nAnswer:<\/strong><\/span>
\nThe atmosphere protects the earth from harmful ultraviolet and infrared rays of the sun. It has oxygen and nitrogen, the life sustaining gases. It helps in retaining the necessary warmth on the earth and helps in the circulation of water vapour as the source of rainfall. These functions of atmosphere keep it in a dynamic state.<\/p>\n
\nWhat is called weather ?
\nAnswer:<\/strong><\/span>
\nWeather is the physical condition or state of atmosphere (temperature, pressure, state of sky etc.) at a given locality or an area.<\/p>\n\n
\n
\n
\n
\nThe rate of absorption of solar radiation by earth and its emission back into space as infra-red waves balances the heat on earth. This phenomenon plays a very important role in maintaining surface temperature of earth. The carbon dioxide and other gases form a blanket around the globe which prevent the passage of infra-red waves from earth back into space. Concentration of solar radiation produces much heat, making earth a very warm place. This phenomenon is similar to that of greenhouse in which the glass enclosed area gets heated up due to its insulation from the rest of the environment. Hence, warming of the atmosphere is due to the greenhouse effect. Hence, Global Warming is also known as Greenhouse Effect.<\/li>\n
\nDescribe the structure of the atmosphere.
\nAnswer:<\/strong><\/span>
\nIn the atmosphere, there are concentric layers of air. Each layer has different density. The upper layers press down the lower one. So, the air of the lower layer is always heavier or denser, while the upper layers are thinner or less dense. In this way about 90 per cent of the mass of air lies within a height of about 20 km from the surface of the earth.
\nOn the basis of the characteristics of temperature and air pressure there exist four thermal layers of the atmosphere. They are \u2014 Troposphere, Stratosphere, Mesosphere and Thermosphere. The Thermosphere is divided into Ionosphere and Exosphere.<\/p>\n
\nHow does atmosphere govern life on earth ?
\nAnswer:<\/strong><\/span>
\nStratosphere absorbs the harmful ultra-violet rays of the sun and the troposphere regulates all weather conditions e.g. ideal temperature, rainfall and their impact on human life.<\/p>\n
\nExplain the factors responsible for depletion of ozone in atmosphere.
\nAnswer:<\/strong><\/span>
\nVarious occupations related to industries, transport and fertilizer cause large amount of CFCs emission along with nitrogen oxide and methane have disturbed the ozone layer depleting the oxygen particles. Volcanic eruptions emit sulphur dioxide creating harmful chemical reactions which dismantle the ozone layer.<\/p>\n
\nGive a description of the recent studies about Global Warming.
\nAnswer:<\/strong><\/span>
\nThe Global mean temperature has increased by 0.6\u00b0C in the 20th century. It is estimated to increase by 1.4\u00b0 to 5.8\u00b0C by the year 2100 from 1990. This has affected abnormal weather conditions in various parts e.g. less rainfall in Africa and Gulf Coast of U.S.A., more rainfall in Asian tropical region and some areas may get no rainfall. Increasing melting of ice and glaciers resulted in rise of oceanic water level by 10 to 25 cm. Warming of atmosphere will considerably increase its moisture carrying capacity. While the troposphere warms up, the stratosphe will cool down.
\nIt is the balance between radiation coming into the atmosphere and radiation going out. Any change in this balance can have rapid impact on life forms on earth because it will have an impact on the sensitivity, adaptability and vulnerability of the whole biospheric system.
\nClimate change will bring about substantial changes in cereal production specially in the Tropics. Global freshwater conditions may worsen by 2025.<\/p>\n
\nWhy should we protect the atmosphere ?
\nAnswer:<\/strong><\/span>
\nAtmosphere is necessary to sustain life on earth, because without atmosphere there would be no oxygen, no weather changes, rainfall etc, which are essential for activities of human life and ideal temperature on the earth.
\nThe atmosphere protects the earth from harmful ultraviolet and infrared rays of the sun. It has oxygen and nitrogen, the life sustaining gases. It helps in retaining the necessaiy warmth on the earth and helps in the circulation of water vapour as the source of rainfall. These functions of atmosphere keep it in a dynamic state.<\/p>\n
\nWhat is known as the Antarctic ozone hole ?
\nAnswer:<\/strong><\/span>
\nOzone hole above the Antarctic region was detected by NASA in the USA. This is due to the emission of CFCs etc. and absence of vegetation cover along Antarctic. CFCs deplete the ozone amount and there is no oxygen addition due to absence of vegetation realm.<\/p>\n
\n(b)<\/strong> Explain the composition of the Atmosphere ?
\n(c)<\/strong> Name different layers of atmosphere. Describe the important characteristics of each layer.<\/p>\n
\n(b)<\/strong> The most important gases composing the atmosphere are nitrogen 78% and oxygen (21%). Therefore, 99% of the atmosphere consists of nitrogen and oxygen. Of the remaining gases, argon accounts for 0.9%. The other gases are carbon dioxide, helium, hydrogen, methane, etc. These gases are called the fixed components of the atmosphere, because their relative proportion is constant in the lower layers of the atmosphere. In addition to fixed components, there are a number of variable components of the atmosphere. The quantity of these components varies from place to place.
\n(c)<\/strong> The atmosphere is composed of the following belts (layer):<\/p>\n\n
\n<\/li>\n\n
\nWhat is the significance of solid particles in the atmosphere ?
\nAnswer:<\/strong><\/span>
\nThe solid particles present in the atmosphere are of dust, smoke, pollen grains and emissions released from chimneys of factories.
\nSignificance :<\/strong> The solid particles present in the atmosphere act as nuclei or the condensation of water vapour around them.<\/p>\n
\nWhat is the significance of Ozone and what are the effects of its depletion ?
\nAnswer:<\/strong><\/span>
\nOzone in the atmosphere acts as a protective umbrella for us by absorbing harmful ultraviolet radiation coming from the sun.
\nEffects of Ozone depletion :<\/strong><\/p>\n\n
\nDefine the following<\/strong><\/p>\n
\n(b)<\/strong> Tropopause
\n(c)<\/strong> Global warming
\n(d)<\/strong> Greenhouse effect
\n(e)<\/strong> Stratosphere
\n(f)<\/strong> Troposphere
\n(g)<\/strong> CFC\u2019s
\n(h)<\/strong> Mesosphere
\n(i)<\/strong> Exosphere
\n(j)<\/strong> Thermosphere<\/p>\n
\n(b) Tropopause\u00a0:<\/strong> The upper limit of the troposphere is called Tropopause.
\n(c) Global warming\u00a0:<\/strong> Gradual rise in Earth\u2019s average temperature is called Global Warming.
\n(d) Greenhouse effect\u00a0:\u00a0<\/strong>The warming up of the atmosphere due to trapping of the solar radiation reflected by the earth by gases like carbon dioxide is called Greenhouse effect.
\n(e) Stratosphere\u00a0:<\/strong> The layer of the atmosphere above the troposphere is called Stratosphere.
\n(f) Troposphere\u00a0:<\/strong> The atmospheric layer closest to the earth is called Troposphere.
\n(g) CFC\u2019s\u00a0:<\/strong> These are chloro-fluoro carbons and are used as propellants in aerosol cans, refrigerants in refrigerators, air conditioning and as solvent cleaners in the microelectronic industry.
\n(h) Mesosphere\u00a0:<\/strong> The layer of th\u00ae atmosphere which extends to a height of 80 km above the stratosphere is called Mesosphere.
\n(i) Exosphere\u00a0:<\/strong> The topmost layer of the atmosphere is called the Exosphere.
\n(j) Thermosphere\u00a0:<\/strong> Ionosphere, which extends from 80 km to 480 km is known as the Thermosphere.<\/p>\n
\nWhat is Atmospheric pressure ?
\nOR<\/strong>
\nIs Atmospheric pressure the same on every place on the surface of the Earth ?
\nAnswer:<\/strong><\/span>
\nAir has weight and, therefore, the atmosphere exerts pressure on the surface of the earth. It has been calculated that at sea level the pressure of air is about 1kg per square centimetre or enough to support a column of mercury 76 cm. in a tube. But with increase of height above sea level the pressure decreases because the overlying column of air goes on getting shorter.<\/p>\n
\nWhy does the atmosphere thin out at higher levels ?
\nAnswer:<\/strong><\/span>
\nThe atmosphere is held by the gravitational force of the Earth and is densest near the Earth\u2019s surface where gravity is maximum. There are concentric layers of air in the atmosphere. Each layer has a different density. The upper layers are continually pressing down on the lower ones. Therefore, the air of the lower layer is always much heavier or denser, while the upper layers are thinner or less dense. Thus atmosphere thins out at higher levels and about 90 per cent of the mass of air lies within a height of about 20 km. from the surface of the earth.<\/p>\n
\nWhat are the properties of Troposphere and Ionosphere?
\nAnswer:<\/strong><\/span>
\nProperties of Troposphere :<\/strong><\/p>\n\n
\n
\nGive reasons for the following :<\/strong><\/p>\n