Composition and Structure of the Atmosphere

Atmosphere

A: 78 B: 21

20 km

Troposphere

All of the above.

Both A and R are true and R is the correct explanation of A.

Explanation — Due to its composition, the atmosphere is the most dynamic entity. Large masses of air are being moved up and down and across the surface of the earth. The energy of the sun is responsible for keeping the atmosphere in a dynamic state.

Troposphere - Stratosphere - Mesosphere - Thermosphere

Exosphere

Ionosphere

Stratopause

Both A and R are true and R is the correct explanation of A.

Explanation — In atmosphere, there are concentric layers of air, each layer having different density. The upper layers press down the lower ones. So, the air of the lower layer is always heavier or denser due to which about 90 per cent of the mass of air lies within a height of about 20 km from the surface of the earth.

Exosphere

All of the above

Meteoric dust particles reflect sunlight causing wispy clouds.

All of the above

Normal lapse rate

Ionosphere

A is true but R is false.

Explanation — The troposphere is not directly heated by incoming solar energy as incoming solar energy directly heats the earth's surface more than the air. The earth's surface absorbs solar radiation and then re-radiates heat upward, warming the troposphere from below.

Radiation Balance

The blanket of air surrounding the Earth is known as the atmosphere.

he atmosphere is a mixture of many gases and tiny solid particles. Atmosphere contains-

1. 78% nitrogen gas
2. 21% oxygen gas
3. The remaining 1% of air is made up of Carbon dioxide, Water Vapour, Helium, Hydrogen, Argon etc.

The four layers of the atmosphere are-

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Thermosphere is the outermost layer of the atmosphere where the satellites orbit the earth.

The troposphere is the lowermost and densest layer of the atmosphere. Its height varies from 18 km at the equator to 8 km at the poles.

Two characteristics of the troposphere are:

1. Seventy-five per cent of the atmosphere is found in the troposphere and its concentration decreases as we go higher from ground level.
2. The troposphere is heated more from below than from above.

The chief characteristics of stratosphere are-

1. The air is thin, cold and dry. The temperature is about -55°C.
2. The Ozone layer lies within the stratosphere. Ozone is generally found between the altitudes of 20 and 50 km.
3. Ozone absorbs the ultraviolet solar radiation coming from above. The insolation received from the Sun is equal to that lost by it. That is why the temperature of the layer is constant. In the higher levels, however, temperature increases with height.
4. The lower layer of the stratosphere has a virtual absence of water vapour and has constant temperature conditions, therefore, it is ideal for flying jet aircraft.
5. Temperature rises from -60°C at the base of the stratosphere to 0°C at stratopause.
6. The upper limit of the stratosphere is known as stratopause.

All the weather conditions occur in the troposphere.

The constituent gases of atmosphere which scientists consider responsible for climate change are Carbon dioxide, Methane, Chlorofluorocarbons, Ozone and Water Vapour.

Pratap did not feel any turbulence because aeroplanes generally fly in the lower stratosphere, where the weather is calm and stable. The troposphere, the layer below the stratosphere, contains all weather phenomena like storms and rain. Since the plane was flying above the troposphere (in the stratosphere), it did not experience the turbulence caused by the storm in Bhubaneswar.

Ozone layer is a layer in the stratosphere of the atmosphere which keeps temperature constant in the lower levels and absorbs ultraviolet rays of the Sun.

Many chemicals like Chlorine, Bromine and Chlorofluorocarbons are leading to depletion of Ozone Layer in the atmosphere. Chlorofluorocarbon compounds escape into the atmosphere and finally break down in the Stratosphere. They produce Chlorine atoms which destroy the Ozone layer.

Sulphur dioxide given out during volcanic eruptions, solar storms and human activities also lead to depletion of Ozone layer.

The effects of ozone layer depletion are as follows:

1. Increased levels of harmful ultraviolet (UV) radiation reaching the Earth's surface.
2. Ultraviolet radiation can lead to skin cancer, eye damage, cataracts and weakened immune systems.
3. It can cause damage to marine ecosystems.
4. Increased UV radiation can harm crops, leading to reduced agricultural productivity and food scarcity.
5. It can affect biogeochemical cycles, including those of nitrogen, sulfur, and carbon.
6. It can influence climate patterns, altering atmospheric temperatures and precipitation levels.

The natural causes of ozone layer depletion are volcanic eruptions and solar flares.

No, ozone in the lower layers of the atmosphere (the troposphere) cannot make up for the loss of ozone in the ozone layer that exists in the stratosphere. This is because the ozone near the earth’s surface is a pollutant and harmful to life, while the ozone in the stratosphere forms a protective layer that absorbs the harmful ultraviolet (UV) rays from the sun.

Thus, ozone in the lower atmosphere cannot perform the protective function that the stratospheric ozone does.

The rise in average mean temperature of the Earth on account of enhanced concentration of greenhouse gases in the atmosphere is known as global warming.

Some important Greenhouse gases are Carbon dioxide, Methane, Chlorofluorocarbons, Ozone and Water Vapour.

The blanket of air surrounding the Earth is known as the atmosphere.

The four layers of the atmosphere are-

1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere

Two functions of the atmosphere are-

1. It protects the Earth from the harmful ultraviolet and infrared rays of the Sun.
2. It helps in retaining the necessary warmth on the Earth.

(i) We find it difficult to breathe when we climb mountains because the layers of atmosphere become thinner at high altitudes. This means that there is less pressure to push the air into the lungs and a lower percentage of Oxygen in the air. This makes it harder to breath.

(ii) The atmosphere is the most dynamic entity because of its composition. Large masses of air are being moved up and down and across the surface of the Earth.

(iii) The troposphere is characterised by regular decrease in temperature with altitude. This decrease in temperature is known as normal lapse rate. The average decrease is 1°C for every 166 metre altitude gain. This temperature variation is responsible for many turbulences which result in all weather phenomena taking place in the troposphere.

The main components of the atmosphere are Nitrogen (78%) and Oxygen (21%). These two gases play a significant role in supporting life on Earth.

1. Oxygen gas helps in burning and breathing. Without breathing oxygen, most living things cannot survive.
2. Nitrogen dilutes the oxygen and slows down the process of oxidation.
3. It is essential for all living things but they cannot use it directly from the atmosphere. Plants obtain it from the soil and animals obtain nitrogen by eating plants or other animals.
4. Nitrogen and Oxygen indirectly help in retaining the necessary warmth on the earth and helps in the circulation of water vapour—the source of rainfall.

The atmosphere consists of concentric layers of air. On the basis of the characteristics of temperature and air pressure, it can be divided into four thermal layers — Troposphere, Stratosphere, Mesosphere and Thermosphere. The Thermosphere is divided into Ionosphere and Exosphere. The four layers are briefly described below:

1. Troposphere — It is the lowermost and densest layer. Its height varies from 18 km at the Equator to 8 km at the Poles.
2. Stratosphere — This layer lies above the Troposphere. It extends to a height of 50 km from sea level. The Ozone layer lies within the stratosphere. Ozone is generally found between the altitudes of 20 and 50 km.
3. Mesosphere — This layer lies above the Stratosphere. It extends to a height of 80 km from ground level.
4. Thermosphere — It lies above Mesosphere and consists of two parts:
   1. Ionosphere — It extends up to a height of about 400 km.
   2. Exosphere — It is the uppermost layer of the atmosphere. It lies between 400 to 1500 km above the earth.

The factors responsible for depletion of Ozone in atmosphere are-

1. Chemicals like Chlorine and Bromine
2. Chlorofluorocarbon gases used in refrigerators, aircraft and air conditioners. CFC compounds escape into the atmosphere and finally break down in the stratosphere, producing Chlorine atoms which destroy the Ozone layer.
3. Sulphur dioxide given out during volcanic eruptions, speeds up destructive chemical reactions.
4. Solar storms consist of coronal mass ejections and solar flares associated with explosions on the surface of the Sun. They also cause Ozone layer depletion.
5. Human activities also result in Ozone layer depletion. Due to bitterly cold Antarctic winter, the stratospheric ice clouds promote the production of chemically active Chlorine and Bromine. This leads to Ozone destruction when sunlight returns in the Antarctic spring.

Three factors that lead to Global Warming are-

1. Destruction of Ozone layer
2. Greenhouse effect in the atmosphere
3. Deforestation

Below diagram shows the Greenhouse Effect:

Conversion of forest land into agricultural land cause global warming in the following ways:

1. Reduction of Carbon Dioxide Absorption: Forests absorb carbon dioxide (CO₂) from the atmosphere in large amount. When forests are cut down to create agricultural land, this ability to absorb CO₂ is reduced. As a result, more carbon dioxide remains in the atmosphere, which contributes to global warming.

2. Release of Stored Carbon: When trees are cut and often burned to clear the land, the carbon stored in trees is released into the atmosphere in the form of carbon dioxide, further increasing the concentration of greenhouse gases. This extra CO₂ traps more heat and raises the Earth's average temperature.

Thus, deforestation for agriculture both reduces CO₂ absorption and increases CO₂ emission, making it a major cause of global warming.

Construction of high rise buildings cause global warming in the following ways:

1. It increases energy consumption as high-rise buildings require large amounts of electricity for lighting, heating, cooling, and operating elevators. Much of this energy is often generated from burning fossil fuels, which releases carbon dioxide (CO₂) into the atmosphere.

2. The construction process itself (manufacturing cement, steel, etc.) releases a significant amount of greenhouse gases, further adding to global warming.

Fossil fuel production cause global warming in the following ways:

1. Burning fossil fuels like coal, oil, and natural gas releases large amounts of carbon dioxide (CO₂) and other greenhouse gases into the atmosphere.

2. These gases trap heat from the sun, leading to a rise in the Earth's temperature, which is the main cause of global warming.

Transportation industry cause global warming in the following ways:

1. Vehicles like cars, trucks, ships, and airplanes burn fossil fuels (petrol, diesel, aviation fuel), releasing large amounts of carbon dioxide (CO₂) and other greenhouse gases into the atmosphere.

2. These gases trap heat and lead to a rise in the Earth's temperature, contributing to global warming.

No single layer of the atmosphere can be considered more significant than the others. Each layer plays a unique and important role in the functioning of the Earth's atmosphere.

All the layers of the atmosphere are interconnected and work together to create a balanced and supportive environment for life on Earth. The layers include the troposphere, stratosphere, mesosphere, thermosphere, and exosphere, each with distinct characteristics and functions.

The troposphere, closest to the Earth's surface, is crucial for weather patterns and the sustenance of life. The stratosphere contains the ozone layer, which protects against harmful ultraviolet radiation. The mesosphere helps protect the Earth from meteoroids. The thermosphere is responsible for the absorption of solar radiation. The exosphere extends into space and allows gases to gradually dissipate.

Therefore, all layers of the atmosphere are essential for maintaining a stable climate, protecting life from harmful radiation, facilitating weather patterns, and supporting the overall functioning of the Earth's ecosystem.

The atmosphere plays a significant role in global warming due to the greenhouse effect. Certain gases in the atmosphere, such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), trap heat from the sun, leading to an increase in the Earth's temperature.

To preserve the atmosphere and mitigate global warming, humans can make the following lifestyle changes:

1. Reduce Carbon Footprint — Minimize the use of fossil fuels by opting for sustainable transportation. Choosing energy-efficient appliances and renewable energy sources like solar or wind power will also help.
2. Conserve Energy — Practice energy-saving habits such as turning off lights and appliances when not in use, using natural lighting, and optimizing heating and cooling systems.
3. Promote Sustainable Agriculture — Support local and organic farming practices that minimize the use of chemical fertilizers and pesticides, reduce food waste, and prioritize sustainable food choices.
4. Conserve Water — Use water efficiently by fixing leaks, employing water-saving devices, and practicing responsible water consumption habits.
5. Adopt Waste Management Practices — Reduce, reuse, and recycle materials to minimize waste generation. Properly dispose of hazardous materials and support recycling initiatives.

One significant effect of climate change that affects me is the increased frequency and intensity of extreme weather events. This includes events such as hurricanes, cyclones, floods, heatwaves, and droughts. These extreme weather events can cause significant damage to infrastructure, disrupt livelihoods, lead to loss of life, and result in economic hardships for affected communities.