Learn about the composition and structure of Earth's atmosphere. Discover the different layers, gases, and their importance in sustaining life.
Structure and Composition of Atmosphere
Atmosphere — compositions and structure; elements of weather and climate
Air and Its Importance
Air is essential for survival; humans cannot survive more than a few minutes without it.
Breathing occurs every few seconds, unlike eating or drinking, which are less frequent.
The atmosphere contains life-supporting gases:
Oxygen: For humans and animals.
Carbon Dioxide: For plants.
Atmospheric Composition: Illustration of the gases and trace elements that make up the Earth’s atmosphere, emphasizing their significance for life.
The Atmosphere
The atmosphere is a mixture of gases, water vapor, and dust particles enveloping the Earth.
Key Features:
Extends 32 km from Earth’s surface (99% of its mass).
Colorless, odorless, and tangible only when it moves as wind.
Composition of the Atmosphere
Gases:
Nitrogen (78%): The largest component.
Oxygen (21%): Supports life.
Argon (0.93%) and trace gases like Carbon Dioxide (0.03%).
Carbon Dioxide:
Transparent to solar radiation, opaque to terrestrial radiation.
Contributes to the greenhouse effect and global warming (due to fossil fuel burning).
Composition of Atmosphere (Percentage): Pie chart representing the percentages of nitrogen, oxygen, carbon dioxide, and other gases in Earth’s atmosphere.
Ozone:
Found between 10-50 km.
Absorbs harmful UV radiation.
Water Vapor:
Varies by region and altitude:
Up to 4% in warm, wet tropics.
Less than 1% in dry, cold deserts and polar regions.
Regulates Earth’s temperature, preventing extreme heat or cold.
Dust Particles:
Origin: Sea salts, soil, smoke, ash, pollen, and meteoric debris.
Found in lower layers but transported to great heights by air currents.
Act as condensation nuclei for cloud formation.
What Causes Weather: An explanation of the factors such as temperature, atmospheric pressure, and humidity that contribute to weather changes.
Structure of the Atmosphere
The atmosphere is divided into five layers based on temperature and density:
Troposphere (0–13 km):
Closest to Earth; contains 75% of the atmospheric mass.
Most weather phenomena occur here.
Temperature decreases by 1°C every 165 m.
Ends at the tropopause, where temperature stabilizes (-80°C at the equator, -45°C at poles).
Stratosphere (13–50 km):
Contains the ozone layer for UV protection.
Structure of the Atmosphere: Diagram illustrating the different atmospheric layers, including the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
Mesosphere (50–80 km):
Temperatures drop to -100°C.
Ends at the mesopause.
Thermosphere (80–400 km):
Contains ions; reflects radio waves.
Temperature increases with altitude.
Exosphere (>400 km):
The outermost layer, transitioning into space.
Role of the Atmosphere
Protects life from harmful UV radiation (ozone layer).
Maintains Earth's temperature balance (greenhouse effect).
Enables weather, climate, and life processes.
Elements of Weather and Climate
Temperature: Affects air density and circulation.
Pressure: Varies with altitude, influencing wind patterns.
Winds: Movement of air.
Humidity: Amount of water vapor in the air.
Clouds and Precipitation: Result from condensation.
Layers of the Atmosphere: A detailed depiction of atmospheric layers and their distinct properties, including temperature variation and gas composition.
Summary of Questions
Multiple Choice:
Major atmospheric gas: Nitrogen.
Most critical layer for humans: Troposphere.
Dust particle association: Dust particles.
Negligible oxygen at: 120 km.
Gas transparent to solar and opaque to terrestrial radiation: Carbon Dioxide.
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