Atmosphere and Climate
Short Questions
1. Which two gases are most abundant in the atmosphere?
Answer: Nitrogen and oxygen are the most abundant gases in the atmosphere.
2. What is the role of water vapour in the atmosphere?
Answer: Water vapour helps in cloud formation and precipitation.
3. Which layer of the atmosphere contains the air we breathe?
Answer: The troposphere contains the air we breathe.
4. In which layer do most weather phenomena occur?
Answer: Most weather phenomena occur in the troposphere.
5. Why do aeroplanes fly in the stratosphere?
Answer: Aeroplanes fly in the stratosphere because it is free from clouds and weather disturbances.
6. What is the main function of the ozone layer?
Answer: The ozone layer protects the Earth by filtering the Sun’s harmful ultraviolet rays.
7. In which layer do most meteorites burn up?
Answer: Most meteorites burn up in the mesosphere.
8. Which layer reflects radio waves back to the Earth?
Answer: The thermosphere reflects radio waves back to the Earth.
9. What is the uppermost layer of the atmosphere?
Answer: The exosphere is the uppermost layer of the atmosphere.
10. What is weather?
Answer: Weather is the hour-to-hour and day-to-day condition of the atmosphere.
11. What is climate?
Answer: Climate is the average weather condition of a place over a long period, usually thirty years or more.
12. What is insolation?
Answer: Insolation is the incoming solar energy received by the Earth from the Sun.
13. Why does temperature decrease from the equator towards the poles?
Answer: Temperature decreases because the amount of insolation decreases from the equator towards the poles.
14. What is humidity?
Answer: Humidity is the amount of water vapour present in the air.
15. What is atmospheric pressure?
Answer: Atmospheric pressure is the pressure exerted by the weight of air on the Earth’s surface.
Long Questions
1. Explain the composition of the atmosphere.
Answer: The Earth’s atmosphere is made up of different gases. Nitrogen forms about 78% and oxygen about 21% of the atmosphere. Small amounts of argon, carbon dioxide, helium, neon, krypton, xenon, ozone, hydrogen, water vapour, and dust particles are also present. Water vapour helps in cloud formation and rainfall.
2. Describe the structure of the atmosphere.
Answer: The atmosphere has five main layers: the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. These layers are formed according to changes in temperature and air density with increasing altitude. Each layer has its own special features and functions.
3. Explain the importance of the thermosphere.
Answer: The thermosphere extends from about 80 km to 700 km above the Earth. It absorbs X-rays and ultraviolet rays from the Sun, reflects radio waves for communication, and is the layer where auroras are seen near the poles.
4. Explain how precipitation occurs.
Answer: Precipitation occurs when the atmosphere becomes saturated with water vapour. The water vapour condenses and falls to the Earth because of gravity. It may fall as drizzle, rain, snow, sleet, or hail. Rain is the most common form of precipitation.
5. Explain how atmospheric pressure affects weather.
Answer: Atmospheric pressure changes with temperature. Warm air rises and creates low-pressure areas, which usually bring cloudy and wet weather. Cold air sinks and forms high-pressure areas, which are generally associated with clear and sunny weather.
6. Explain land breeze and sea breeze.
Answer: A sea breeze blows from the sea to the land during the day because the land becomes hotter than the sea. A land breeze blows from the land to the sea during the night because the land cools faster than the sea. These local winds help moderate the climate in coastal areas.
7. Describe the four main seasons recognised by the Indian Meteorological Department.
Answer: The Indian Meteorological Department recognises four seasons: Winter (December to early April), Summer or Pre-monsoon (April to June), Monsoon or Rainy season (June to September), and Post-monsoon (October to December). Each season has its own weather conditions.
8. Explain the south-west monsoon.
Answer: The south-west monsoon occurs from June to September. During summer, the land heats faster than the sea, creating low pressure over land. Moist winds blow from the sea towards the land and bring most of India’s annual rainfall.
9. Explain the north-east monsoon.
Answer: The north-east monsoon occurs from October to February. During this period, the land cools faster than the sea. Cold and dry winds blow from land to sea. After passing over the Bay of Bengal, they bring rainfall mainly to Tamil Nadu, Andhra Pradesh, and parts of Karnataka.
10. What is climate change? How can it be reduced?
Answer: Climate change means long-term changes in weather patterns caused mainly by human activities such as burning fossil fuels, cutting forests, and industrial pollution. It can be reduced by lowering carbon emissions, using renewable energy, protecting forests, and following sustainable lifestyles.
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