| Book Name | : School Geography |
| Subject | : Geography |
| Class | : 10 (Madhyamik) |
| Publisher | : Bengal Book Syndicate Pvt. Ltd |
| Chapter Name | : Atmosphere |
Identify the correct answers
Question 1
The percentage of oxygen in the atmosphere is :
- 80.5%
- 20.9%
- 29.9%
- 40.9%
Answer
(b) 20.9%
Explanation :
The percentage of oxygen in the atmosphere is 20.9%.
Question 2
The layer of the atmosphere where changes in daily weather take place is called :
- Troposphere
- Stratosphere
- Exosphere
- lonosphere
Answer
(a) Troposphere
Explanation:
The layer of the atmosphere where changes in daily weather take place is called the Troposphere.
Question 3
- early in the morning
- at night
- at noon
- in the evening
Answer
(b) At noon
Explanation:
The strongest insolation of a day is received at noon.
Question 4
The loo is a
- periodical
- local
- permanent
- sudden wind
Answer
(b) local wind
Explanation:
The loo is a local wind.
Question 5
The temperature decreases at the rate of
- 6·4°C/1000 metres
- 6·06°C/1000 metres
- 0·06°C/1000 metres
- 16·06°C/1000 metres
Answer
(a) 6.4°C/1000 meters
Explanation:
The temperature decreases at the rate of 6.4°C/1000 meters.
Question 6
The subtropical High-pressure belt lies between :
- 25°-35° North and South
- 60°-70° North and South
- 0°-10° North and South
- 35°-65° North and South latitudes
Answer
25°-35° North and South latitudes
Explanation:
The subtropical High-pressure belt lies between 25°-35° North and South latitudes.
Question 7
The factor that increases changes of rainfall is
- increase in humidity
- decrease in humidity
- rise in air temperature
- none of these
Answer
(a) increase in humidity
Explanation:
The factor that increases the chances of rainfall is an increase in humidity. As the amount of water vapor in the air increases, the likelihood of precipitation also increases. Other factors such as air temperature, pressure, and atmospheric stability also play a role in determining the occurrence and intensity of rainfall.
Question 8
The slope of the Himalayas in India that is warmer is
- eastern slope
- northern slope
- southern slope
- western slope
Answer
(c) Southern slope
Explanation:
The slope of the Himalayas in India that is warmer is the southern slope.
If the sentence is true write T and if false write F against the following:
Question
- Two major constituent gases of air include nitrogen and xenon.
- Vertical rays of the sun are cooler than slanting rays.
- Conduction is the process by which heat is transferred by contact.
- The most abundant gas in the atmosphere is oxygen.
- The wind velocity is so high and roaring at 40°S latitude that it is called ‘Horse latitude.
- Convectional rainfall occurs in the equatorial region.
- Atmosphere of the earth is heated by 66% of incoming solar radiation.
- The uppermost layer of atmosphere is magnetosphere.
Answer
- False
Xenon is present in trace amounts in the atmosphere, with a concentration of only 0.000009%. Nitrogen, on the other hand, is the most abundant gas in the atmosphere, making up about 78% of it. - False
Vertical rays of the sun are more intense than slanting rays as they cover a smaller area of the earth’s surface, thus concentrating the sun’s energy on a smaller area. This results in more heating and higher temperatures. - True
- False
While oxygen is an important gas in the atmosphere and is necessary for the survival of many organisms, it is not the most abundant gas. Nitrogen is the most abundant gas in the atmosphere, making up about 78% of it. - False
The region around 30 degrees north and south of the equator is known as the horse latitudes. These regions are characterized by calm winds and high pressure. - True
- False
The atmosphere of the Earth is heated by only about 2% of incoming solar radiation. Most of the solar radiation is absorbed by the Earth’s surface, which then re-radiates it as heat. - False.
The magnetosphere is not a layer of the atmosphere, but rather the region surrounding the Earth that is influenced by the Earth’s magnetic field. The uppermost layer of the atmosphere is the exosphere, which gradually fades into the vacuum of space.
Fill in the blanks with appropriate words:
- The ____ layer absorbs the ultraviolet rays of the sun.
- ____ is the process by which heat waves are sent out by the earth’s surface.
- The difference between maximum and minimum temperatures is called the ____ of temperature.
- ____ facing slopes of the mountains are warmer.
- The ____ zone is the hottest part of the earth.
- ____ are imaginary lines that connect places having equal pressure reduced to sea level.
- The tropical cyclone has a ____ pressure centre.
Answer
- The ozone layer absorbs the ultraviolet rays of the sun.
- Radiation is the process by which heat waves are sent out by the earth’s surface.
- The difference between maximum and minimum temperatures is called the range of temperature.
- South-facing slopes of the mountains are warmer.
- The Torrid Zone is the hottest part of the earth.
- Isobars are imaginary lines that connect places having equal pressure reduced to sea level.
- The tropical cyclone has a low pressure center.
Answer in word or words:
Question 1
What is the imaginary line joining places having equal temperature called ?
Answer
The imaginary line joining places having equal temperature is called an isotherm.
Question 2
What is the warm, nutrient-poor water off Northern Peru called ?
Answer
The warm, nutrient-poor water off Northern Peru is called the “Humboldt Current” or the “Peruvian Current”.
Question 3
Name the instrument used to measure air pressure.
Answer
The instrument used to measure air pressure is called a barometer.
Question 4
What do we call the winds that blow from one direction throughout the year?
Answer
The winds that blow from one direction throughout the year are called “permanent winds” or “planetary winds”.
Question 5
What is the warm dry wind blowing along the leeward slope of the Alps called ?
Answer
The warm, dry wind blowing along the leeward slope of the Alps is called the foehn wind.
Question 6
Name the rainfall that occurs in the presence of a mountain or a plateau.
Answer
The rainfall that occurs in the presence of a mountain or a plateau is called orographic rainfall.
Match column A with column B:
| Column A | Column B |
| (1) Troposphere | (a) In the southern hemisphere an anti-cyclones moves |
| (2) Anti-clockwise | (b) Formation of Fog |
| (3) Condensation | (c) During Day |
| (4) Sea breeze | (d) Pressure at sea level |
| (5) 1013 mb | (e) Lower most layer of the atmosphere. |
Answer
(1) Troposphere (e) Lower most layer of the atmosphere.
(2) Anti-clockwise (a) In the southern hemisphere an anti-cyclones moves
(3) Condensation (b) Formation of Fog
(4) Sea breeze (c) During Day
(5) 1013 mb (d) Pressure at sea level
Short answer type questions
Question 1
What is Ionosphere?
Answer
The ionosphere is a layer of the Earth’s atmosphere located between 60 km and 1,000 km above the surface. It is named for its ionized gas, which is created by the Sun’s ultraviolet radiation. This layer is responsible for the reflection and refraction of radio waves, which enables long-distance radio communication.
Question 2
What do you mean by Inversion of temperature?
Answer
Inversion of temperature refers to a situation where the normal decrease in temperature with increasing altitude in the troposphere is reversed, and temperature instead increases with altitude. This usually occurs when a layer of warm air overlays a layer of cooler air near the surface, which traps pollutants and moisture, leading to reduced visibility and poor air quality.
Question 3
What is Doldrum?
Answer
The Doldrums is a region of the ocean near the equator that is characterized by calm or light variable winds. It is also known as the Intertropical Convergence Zone (ITCZ) where the trade winds of the northern hemisphere meet the southern hemisphere’s westerlies. The air at the Doldrums is humid and warm, and it is known for frequent thunderstorms and rain showers.
Question 4
What is meant by Chinook?
Answer
Chinook is a warm, dry wind that blows down the eastern slope of the Rocky Mountains. It is also known as a foehn wind.
Question 5
What is insolation?
Answer
Insolation refers to the amount of solar radiation that reaches the Earth’s surface. It is affected by various factors such as the angle of incidence, atmospheric conditions, and the distance between the Earth and the Sun. Insolation plays a crucial role in regulating the Earth’s climate and driving weather patterns.
Question 6
How does rainfall take place?
Answer
Rainfall takes place through the process of condensation and precipitation. Water vapour in the atmosphere cools and condenses into tiny droplets or ice crystals, forming clouds. When the droplets or ice crystals become too heavy to be suspended in the air, they fall to the ground as precipitation in the form of rain, snow, sleet, or hail. The amount and type of precipitation depend on various factors such as temperature, humidity, and air pressure.
Question 7
Why is fog not considered as precipitation?
Answer
Fog is not considered as precipitation because it does not fall to the ground like rain, snow, sleet, or hail. Precipitation is defined as any form of water that falls from the atmosphere and reaches the ground. Fog is a type of cloud that forms when the air is cooled to its dew point, causing water vapor to condense into tiny droplets. While these droplets may reduce visibility and can settle on surfaces, they do not fall to the ground as precipitation.
Question 8
What is relative humidity?
Answer
Relative humidity is the amount of water vapor present in the air, expressed as a percentage of the maximum amount that the air could hold at that temperature and pressure. It is a measure of how close the air is to being saturated with water vapor.
Answer the following questions
Question 1
What is the composition of the atmosphere?
Answer
The Earth’s atmosphere is primarily composed of nitrogen (78%) and oxygen (21%) along with small amounts of other gases such as argon, carbon dioxide, neon, helium, and hydrogen. There are also trace amounts of water vapor, ozone, and other gases. The exact composition can vary depending on factors such as location and altitude.
Question 2
What are isobar and isotherms?
Answer
Isobars are imaginary lines on a weather map that connect areas of equal atmospheric pressure. These lines help meteorologists analyze and forecast weather patterns.
Isotherms are imaginary lines on a weather map that connect areas of equal temperature. These lines help meteorologists identify areas of warm or cold air and track changes in temperature over time.
Question 3
Why vertical rays of the sun are hotter than slanting rays?
Answer
Vertical rays of the sun are hotter than slanting rays because when the sun’s rays fall vertically, the same amount of solar energy is concentrated on a smaller surface area compared to when the rays fall at an angle. As a result, the same amount of solar energy is spread over a larger surface area, reducing the intensity of the heat. This is why the temperature is higher at the equator, where the sun’s rays fall almost vertically, than at the poles, where the rays fall at an angle.
Question 4
What is Ferrel’s law?
Answer
Ferrel’s law is a concept in atmospheric science that explains the behavior of prevailing winds in the mid-latitudes. It states that in the middle latitudes, air moving towards the poles from the subtropics is deflected by the Coriolis effect and turns to the east. At the same time, air moving towards the equator from the higher latitudes is also deflected to the east.
Question 5
Distinguish between weather and climate?
Answer
| Weather | Climate |
|---|---|
| Refers to atmospheric conditions in a shorter span of time (hours, days, weeks) | Refers to long-term atmospheric conditions in a particular region (decades, centuries, millennia) |
| Constantly changing and varies from day to day and season to season | Remains relatively constant and predictable over a long period of time |
| Describes the state of the atmosphere at a specific place and time | Describes the average weather pattern of a region over a long period of time |
| Is affected by local factors like temperature, pressure, humidity, and precipitation | Is influenced by regional factors such as latitude, altitude, ocean currents, and prevailing winds |
Question 6
What are the characteristics of troposphere?
Answer
The troposphere is the lowest layer of the Earth’s atmosphere, extending up to 7-20 km from the Earth’s surface depending on the location. Some of its key characteristics include:
- Temperature: Temperature decreases with increasing altitude at an average rate of 6.5°C per km.
- Weather phenomenon: The weather phenomenon like clouds, precipitation, thunderstorms, etc., occur in this layer.
Question 7
Why is the lonosphere beneficial to the planet earth?
Answer
The ionosphere is beneficial to the planet Earth because it absorbs the harmful and highly energetic radiation from the sun, such as X-rays, gamma rays, and ultraviolet (UV) radiation. The ionosphere is composed of ions and free electrons, which are produced by the ionization of atmospheric gases due to the absorption of solar radiation.
Question 8
How does the difference of latitude affect the temperature condition of the atmosphere?
Answer
The temperature condition of the atmosphere is affected by the difference of latitude in the following ways:
- Temperature decreases towards the poles: As we move away from the equator towards the poles, the temperature decreases due to the decrease in the intensity of solar radiation.
- Unequal heating of land and water: The temperature of the air is also affected by the unequal heating of land and water. Land heats up and cools down faster than water, so areas near the coast tend to have a more moderate climate than areas inland.
Question 9
Discuss the effects of altitude on the temperature condition of a region.
Answer
Altitude, or the height above sea level, has a significant effect on the temperature condition of a region. As one goes higher in the atmosphere, the atmospheric pressure decreases and the air becomes less dense. This leads to a decrease in temperature, which is known as the lapse rate.
Question 10
How do you consider the distance from the sea as a factor of the temperature variation of the atmosphere?
Answer
The distance from the sea is an important factor that influences the temperature variation of the atmosphere. Generally, the temperature of places located near the sea is milder compared to those located inland. This is because the sea moderates the temperature by absorbing and releasing heat slower than the land.
Question 11
Explain why the monsoon is a periodical wind?
Answer
The monsoon is a periodical wind because it undergoes a seasonal reversal in direction. During summer, the landmass gets heated more than the surrounding water bodies, causing the low-pressure area over the land. This causes the wind to blow from the ocean towards the land, bringing moisture and resulting in the rainy season. In winter, the landmass cools down faster than the surrounding water bodies, resulting in a high-pressure area over the land. This causes the wind to blow from the land towards the ocean, resulting in a dry season.
Question 12
Mention three different characteristics of the stratosphere.
Answer
Three different characteristics of stratosphere are:
- Temperature: The temperature of the stratosphere increases with altitude due to the absorption of ultraviolet radiation by ozone.
- Ozone Layer: The stratosphere contains a high concentration of ozone, which absorbs harmful ultraviolet radiation from the sun, protecting life on Earth.
- Airplane flight: The stratosphere is the layer in which airplanes fly. This is because it is stable and free of weather disturbances, and its low air density reduces drag on the aircraft.
Question 13
Which type of rainfall is common in the equatorial regions? Explain its origin.
Answer
Convective rainfall is common in the equatorial region. It is caused by the intense heating of the earth’s surface due to the direct overhead sun, leading to the formation of low-pressure zones. The moist air rises rapidly, cools, and forms cumulonimbus clouds, resulting in heavy rainfall. The rainfall is often intense, brief, and occurs mostly in the afternoon.
Question 14
Compare sea breeze and land breeze.
Answer
| Sea Breeze | Land Breeze |
|---|---|
| Wind blows from sea towards land | Wind blows from land towards sea |
| Occurs during the day | Occurs during the night |
| Caused due to temperature differences between land and sea | Caused due to temperature differences between land and sea |
| Cool and refreshing | Warm and dry |
Question 15
How is planetary wind different from periodic wind?
Answer
| Planetary Wind | Periodic Wind |
|---|---|
| These are the global winds that blow throughout the year in a particular direction. | These winds are seasonal, and they change their direction with the change in seasons. |
| The direction of planetary winds is influenced by the earth’s rotation, and they are driven by pressure differences. | The direction of periodic winds is influenced by the differential heating of land and water, and they are driven by local pressure differences. |
| Examples of planetary winds are trade winds, westerlies, and polar easterlies. | Examples of periodic winds are monsoons, sea and land breezes, and mountain and valley winds. |
Question 16
Write the differences between cyclones and anticyclones.
Answer
| Cyclones | Anticyclones |
|---|---|
| A region of low atmospheric pressure | A region of high atmospheric pressure |
| Air moves towards the center in a counterclockwise direction (northern hemisphere) and clockwise direction (southern hemisphere) | Air moves away from the center in a clockwise direction (northern hemisphere) and counterclockwise direction (southern hemisphere) |
| Winds blow inwards towards the center | Winds blow outwards away from the center |
Solve the puzzle from the clues given
Clues-
Across
(1) The layer of air through which jet planes fly.
(2) In lonosphere this takes place.
(3) The temperature at which an airmass gets saturated.
Down
(4) In this region temperature is high throughout the year (hottest region).
(5) An important factor affecting temperature variation.
(6) The layer of air that absorbs sun’s ultra violate rays.
Answer
Across (1) Stratosphere (2) Ionization (3) Dew
Down (4) Tropics (5) Land distance (6) Ozone
Long answer or essay-type questions
Question 1
Account for the differences in temperature and pressure conditions in the atmosphere.
Answer
The differences in temperature and pressure conditions in the atmosphere can be attributed to various factors including latitude, altitude, distance from the sea, topography, and air masses.
- Latitude: Temperature and pressure vary with latitude due to the difference in the angle at which the sun’s rays strike the earth’s surface. This results in a variation of temperature and pressure from the equator towards the poles.
- Altitude: As we move higher in the atmosphere, the pressure decreases and temperature decreases with height. This is because there are fewer air molecules in the higher atmosphere.
Question 2
How many pressure belts are there on the surface of the earth? Discuss them, in brief.
Answer
There are three pressure belts on the surface of the earth – the Equatorial Low Pressure Belt, the Subtropical High Pressure Belts, and the Polar High Pressure Belts.
- Equatorial Low Pressure Belt: It is also known as the Doldrums. This belt is characterized by low pressure, convergence of trade winds, and ascending air. The intense heating of the equator results in warm air rising and spreading towards the poles.
- Subtropical High Pressure Belts: These belts are also known as the Horse Latitudes. They are characterized by high pressure, descending air, and dry weather conditions. These belts are located around 30 degrees north and south of the equator.
- Polar High Pressure Belts: These belts are characterized by high pressure, descending air, and extremely cold weather conditions. These belts are located around the poles.
Question 3
Describe the layers of atmosphere with sketch.
Answer
The atmosphere is typically divided into five layers based on temperature changes with altitude. These layers, starting from the surface of the Earth, are:
- The Troposphere – the lowest layer where we live and where weather occurs. It extends up to about 12 km (7.5 miles) in altitude.
- The Stratosphere – contains the ozone layer which absorbs harmful UV radiation. It extends from the top of the troposphere to about 50 km (31 miles) in altitude.
- The Mesosphere – the coldest layer of the atmosphere where temperatures can drop below -100°C (-148°F). It extends from the top of the stratosphere to about 85 km (53 miles) in altitude.
- The Thermosphere – the layer where the auroras occur, and where the temperature can reach over 1000°C (1832°F) due to the absorption of solar radiation. It extends from about 85 km (53 miles) to 600 km (373 miles) in altitude.
- The Exosphere – the outermost layer of the atmosphere where the air is very thin and gradually merges with the vacuum of space. It extends from about 600 km (373 miles) to 10,000 km (6,200 miles) in altitude.
Question 4
Discuss about the importance of air temperature as an element of weather.
Answer
Air temperature is one of the essential elements of weather that has significant importance in determining the weather conditions of a region. The following are the importance of air temperature:
- Weather prediction: Air temperature is a crucial element in predicting weather conditions. Meteorologists use temperature data to make forecasts about future weather patterns, including precipitation, wind patterns, and cloud cover.
- Human comfort: Air temperature affects human comfort and health. Excessively high or low temperatures can cause heatstroke, hypothermia, and other health problems. Therefore, it is important to regulate indoor temperature to maintain a comfortable living and working environment.
- Agriculture: Air temperature is essential in agriculture. Plants require specific temperature ranges to grow and produce, and the timing of planting and harvesting is often based on temperature patterns.
Question 5
Discuss the three major factors which affect the temperature condition of a region.
Answer
The three major factors that affect the temperature condition of a region are:
- Latitude: The latitude of a place is the distance of that place from the equator. As the distance from the equator increases, the temperature decreases. This is because the sun’s rays are more direct near the equator and become more slanted as they move towards the poles.
- Altitude: Altitude is the height of a place above sea level. As we go higher in altitude, the temperature decreases. This is because the air becomes less dense and can hold less heat.
- Distance from the sea: The temperature condition of a region is also influenced by its distance from the sea.
Question 6
What are the factors responsible for the variation air pressure of a region?
Answer
There are several factors that can cause variations in air pressure of a region, including:
- Altitude: As we move higher up in the atmosphere, the air pressure decreases because the weight of the air above becomes less.
- Temperature: When air is heated, it expands and becomes lighter, resulting in lower air pressure. Conversely, when air is cooled, it contracts and becomes denser, resulting in higher air pressure.
- Humidity: Water vapor is lighter than dry air, which means that an increase in humidity can result in a decrease in air pressure. This is because the water vapor takes up space that would otherwise be occupied by dry air.
Question 7
Draw a diagram and describe the heat zones of the earth.
Answer
The Earth’s heat zones are based on the distribution of solar radiation across the planet. There are three main heat zones of the Earth, which are frigid, temperate, and torrid zones:
- Frigid Zone: This is the zone around the poles, from 66.5 to 90 degrees latitude. The temperature in this zone is generally very low, and the polar ice caps are located in this zone. The sun’s rays strike the earth at a very low angle, resulting in less heating.
- Temperate Zone: This zone lies between the frigid and torrid zones, from 23.5 to 66.5 degrees latitude. The temperature in this zone varies from season to season and is moderate, with four distinct seasons.
- Torrid Zone: This is the zone near the equator, from 23.5 degrees north to 23.5 degrees south. The temperature in this zone is generally high and the climate is tropical. The sun’s rays strike the earth directly, resulting in maximum heating.
Question 8
Explain why low-pressure belt prevails over the equatorial region?
Answer
The equatorial region receives intense heat from the sun throughout the year. As a result, the air in this region is heated, expands, and rises up, creating a region of low pressure. This low-pressure region is known as the Inter-Tropical Convergence Zone (ITCZ).
The ITCZ is formed by the convergence of the trade winds from the northern and southern hemispheres. As the warm, moist air rises and cools, it forms clouds and leads to heavy precipitation in the equatorial region. This results in a continuous cycle of warm air rising and cooler air descending, creating a region of low pressure.
Question 9
What do you mean by shifting of pressure belt? Explain how do they affect the global wind system.
Answer
Shifting of pressure belts refers to the movement of the high and low-pressure systems across the earth’s surface. These pressure systems move towards the poles during summer and towards the equator during winter due to the uneven heating of the earth’s surface.
The shifting of pressure belts affects the global wind system by causing changes in the direction, strength, and speed of the winds. For example, the equatorial low-pressure belt shifts towards the north during the summer months in the Northern Hemisphere, which causes the monsoon winds to blow from the Indian Ocean towards the Indian subcontinent.
Question 10
Describe the different local winds.
Answer
Local winds are the winds that blow over a small area or region and are influenced by the local factors like topography, temperature, and pressure. Some of the major local winds are:
- Sea Breeze: Sea breeze blows during the daytime from the sea towards the land. It occurs due to the temperature difference between the land and sea. The land heats up faster than the sea, causing the air above the land to rise, and the cool air from the sea flows in to replace it.
- Land Breeze: Land breeze blows during the night from the land towards the sea. It occurs due to the temperature difference between the land and sea. The land cools down faster than the sea, causing the air above the sea to rise, and the cool air from the land flows in to replace it.
- Mountain and Valley Breeze: Mountain and valley breeze occur due to the temperature difference between the mountain and valley areas. During the day, the mountain areas heat up faster than the valley areas, and the warm air rises, causing the cool air from the valley to flow up the mountain.
Question 11
Give a short description of different types of rainfall.
Answer
There are three main types of rainfall:
- Convectional rainfall: This occurs in areas with high temperatures and humidity. The sun heats the ground, causing the air to rise and cool. As the air cools, water vapour condenses into clouds, and precipitation occurs.
- Orographic rainfall: This occurs when moist air is forced up over a mountain or other elevated landform. As the air rises, it cools and condenses, resulting in precipitation. The windward side of the mountain receives more rainfall than the leeward side.
- Frontal rainfall: This occurs when two air masses of different temperatures and humidity meet.
Question 12
Describe the origin and direction of the planetary winds on the earth.
Answer
Planetary winds are large-scale winds that blow steadily and constantly in a particular direction over a vast region. They are also known as the prevailing winds. The planetary winds on the earth are mainly classified into three types:
- Polar easterlies: These winds blow from the polar high-pressure belt towards the sub-polar low-pressure belt, from the east to the west.
- Westerlies: These winds blow from the sub-polar low-pressure belt towards the sub-tropical high-pressure belt, from the west to the east.
- Trade winds: These winds blow from the sub-tropical high-pressure belt towards the equatorial low-pressure belt, from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.
These winds are caused due to the differences in temperature and pressure across the globe. The rotation of the earth and the Coriolis effect also play a significant role in shaping the planetary wind patterns.
Question 13
What is the importance of ozone in the atmosphere? Discuss the factors responsible for its depletion.
Answer
Importance of Ozone in the atmosphere:
- The ozone layer present in the stratosphere protects the Earth from the harmful ultraviolet radiation of the sun.
- It helps in maintaining the temperature balance of the earth’s atmosphere.
- Ozone is also used in medical and industrial applications.
Factors responsible for the depletion of Ozone:
- Human-made chemicals such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are used in refrigeration, air conditioning, aerosol sprays, and foam blowing.
- Increased emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) from industrial activities and transportation.
- Natural phenomena such as volcanic eruptions and solar flares can also contribute to ozone depletion.
Question 14
Discuss the role of greenhouse gases in causing global warming. Write the effects of global warming.
Answer
Greenhouse gases are gases in the atmosphere that trap heat radiated from the Earth’s surface, resulting in an increase in the Earth’s temperature. Carbon dioxide, methane, water vapor, and nitrous oxide are some of the major greenhouse gases.
The effects of global warming are numerous and include:
- Rising global temperatures: The average global temperature has increased by about 1°C since the pre-industrial era, and this increase is projected to continue.
- Melting of polar ice caps: The melting of polar ice caps has led to rising sea levels, which could cause flooding and displacement of coastal populations.
- Extreme weather events: Global warming has led to an increase in extreme weather events such as heatwaves, droughts, and heavy rainfall.
Question 15
Describe the Jet streams and write about its relation with the monsoon.
Answer
Jet streams are fast-flowing, narrow air currents in the upper atmosphere, located at about 30,000-50,000 feet above the surface of the Earth. There are two primary jet streams in each hemisphere: the polar jet stream and the subtropical jet stream.
The jet stream affects the monsoon by bringing warm, moist air from the Indian Ocean. Its location and intensity affect the timing, duration, and amount of rainfall during the monsoon season. Climate change may alter the jet stream and have significant impacts on the monsoon and other weather patterns.
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