GeographyClass 11CLIMATE

CLIMATE | Class 11 Geography Notes

By ConceptScroll Team · Published on 17 July 2026 · 4 min read

CLIMATE – this guide gives you a concise, exam-ready overview of CLIMATE from Class 11 Geography, written by ConceptScroll editors and reviewed against the latest NCERT textbook.

Gases

The atmosphere consists of several gases, each playing a specific role. Nitrogen is the most abundant gas, making up about 78% of the atmosphere, and is largely inert. Oxygen, about 21%, is vital for respiration in animals and humans. Argon and other inert gases constitute about 1%. Carbon dioxide, though only about 0.03%, is crucial for the greenhouse effect. It allows incoming solar radiation to pass through but absorbs and re-radiates terrestrial radiation emitted by the Earth, thus warming the atmosphere. The concentration of carbon dioxide has been increasing due to human activities such as burning fossil fuels and deforestation, leading to global warming and climate change. Ozone is another important gas found mainly between 10 and 50 km altitude in the stratosphere. It absorbs harmful ultraviolet radiation from the sun, preventing it from reaching the Earth's surface and protecting living organisms from its damaging effects. Without ozone, life on Earth would be severely affected by increased ultraviolet radiation. The volume of other gases remains relatively constant with altitude, but oxygen becomes negligible at about 120 km. Carbon dioxide and water vapour are found only up to about 90 km. These gases collectively maintain the Earth's temperature and support life.

📊 Diagram: Figure 7.1 depicts the ozone layer within the stratosphere and shows the variation of gases with altitude.

🧪 Activity: No specific activity in this section.

🔗 Connection: This section connects to the next on water vapour and dust particles, completing the understanding of atmospheric composition.

Frequently asked questions

1. Multiple choice questions. (i) Which one of the following gases constitutes the major portion of the atmosphere? (a) Oxygen (c) Argon (b) Nitrogen (d) Carbon dioxide (ii) Atmospheric layer important for human beings is: (a) Stratosphere (c) Troposphere (b) Mesosphere (d) Ionosphere (iii) Sea salt, pollen, ash, smoke soot, fine soil — these are associated with: (a) Gases (c) Water vapour (b) Dust particles (d) Meteors (iv) Oxygen gas is in negligible quantity at the height of atmosphere: (a) 90 km (c) 100 km (b) 120 km (d) 150 km (v) Which one of the following gases is transparent to incoming solar radiation and opaque to outgoing terrestrial radiation? (a) Oxygen (c) Helium (b) Nitrogen (d) Carbon dioxide

(i) (b) Nitrogen: Nitrogen constitutes about 78% of the atmosphere, making it the major component.

(ii) (c) Troposphere: This is the lowest layer of the atmosphere where weather phenomena occur and humans live.

(iii) (b) Dust particles: Sea salt, pollen, ash, smoke soot, and fine soil are types of dust particles suspended in the atmosphere.

(iv) (d) 150 km: Oxygen gas becomes negligible at heights around 150 km in the atmosphere.

(v) (d) Carbon dioxide: CO2 is transparent to incoming solar r

2. Answer the following questions in about 30 words. (i) What do you understand by atmosphere? (ii) What are the elements of weather and climate? (iii) Describe the composition of atmosphere. (iv) Why is troposphere the most important of all the layers of the atmosphere?

(i) Atmosphere is the layer of gases surrounding the Earth, held by gravity, essential for life and climate.

(ii) Elements of weather and climate include temperature, humidity, precipitation, wind, pressure, and cloudiness.

(iii) The atmosphere is composed mainly of nitrogen (78%), oxygen (21%), argon, carbon dioxide, water vapour, and trace gases.

(iv) Troposphere is important because it contains most of the atmospheric mass, weather phenomena occur here, and it supports life.

3. Answer the following questions in about 150 words. (i) Describe the composition of the atmosphere. (ii) Draw a suitable diagram for the structure of the atmosphere and label it and describe it.

(i) The atmosphere is a mixture of gases surrounding the Earth. It mainly consists of nitrogen (78%), oxygen (21%), argon (0.93%), carbon dioxide (0.03%), and trace gases. Water vapour varies from 0 to 4% depending on location and weather. These gases are essential for life, weather, and climate. Nitrogen is inert and provides bulk, oxygen supports respiration, carbon dioxide is important for photosynthesis and greenhouse effect, and water vapour influences weather and temperature.

(ii) [Diagra

Which one of the following gases constitutes the major portion of the Earth's atmosphere?

Nitrogen