Class 11 Geography - KERALA
Composition and Structure of Atmosphere
This chapter explores the composition and vertical structure of Earth's atmosphere, which is essential for life. Students will learn about the proportions of permanent and variable gases like nitrogen, oxygen, carbon dioxide, and water vapor, as well as dust particles. The chapter details the five distinct atmospheric layers—troposphere, stratosphere, mesosphere, thermosphere, and exosphere—based on temperature variations. Understanding these concepts is crucial for Kerala SCERT Class 11 board exams as questions frequently test the role of greenhouse gases, the significance of the ozone layer, and temperature changes with altitude.
Start Learning FreeKey Concepts
Permanent Gases of Atmosphere
Nitrogen (78%) and Oxygen (21%) make up the bulk of the atmosphere and remain in relatively constant proportions globally.
Variable Gases and Aerosols
Gases like carbon dioxide, water vapor, and dust particles fluctuate in amount and play a vital role in weather processes and absorbing terrestrial radiation.
Troposphere
The lowest layer of the atmosphere where all weather phenomena occur, characterized by a decrease in temperature with increasing height at the normal lapse rate.
Stratosphere
The layer above the troposphere that contains the ozone layer, which absorbs harmful ultraviolet rays and causes temperatures to increase with altitude.
Inversion of Temperature
A rare meteorological condition where temperature increases with altitude instead of decreasing, often observed during long winter nights.
Important Formulas
Board Exam Info
In the Kerala SCERT Class 11 Geography examinations, this chapter typically carries around 4 to 6 marks. Common question types include direct definitions of atmospheric layers, drawing and labeling the structure of the atmosphere, and reasoning questions about the normal lapse rate or the importance of the ozone layer.
Frequently Asked Questions
Why does temperature decrease with height in the troposphere?
The troposphere is heated from below by the Earth's surface (terrestrial radiation) rather than directly by the sun, so the air gets colder the further it is from the heat source.
What is the significance of the ozonosphere?
Located in the stratosphere, the ozonosphere absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth from skin cancer and other biological damages.
Why is carbon dioxide considered meteorologically very important?
Even though it is present in a small quantity, carbon dioxide is transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, making it a key greenhouse gas responsible for trapping heat.
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