Earth's Atmosphere: Composition and Layers

• The atmosphere is a mixture of gases that surrounds a planet (like Earth).

Composition of Earth's Atmosphere

• Earth's atmosphere is primarily composed of nitrogen (about 78%) and oxygen (about 21%).
• Other gases, including argon, carbon dioxide, neon, helium, hydrogen, and ozone, make up a small percentage.
• Water vapor is also present in varying amounts.

Layers of the Atmosphere

• The atmosphere is divided into distinct layers based on temperature variations.
• The main layers, from lowest to highest altitude, are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.

Troposphere

• The troposphere is the lowest layer, extending from the surface up to about 7-20 km.
• It contains most of the atmosphere's mass and water vapor.
• Temperature decreases with altitude in the troposphere.
• This is where almost all weather phenomena occur.

Stratosphere

• The stratosphere extends from the top of the troposphere to about 50 km altitude.
• Temperature increases with altitude due to the absorption of ultraviolet (UV) radiation by the ozone layer.
• The ozone layer is located in the stratosphere and is crucial for absorbing harmful UV radiation from the sun.

Mesosphere

• The mesosphere extends from the top of the stratosphere to about 85 km altitude.
• Temperature decreases with altitude, making it the coldest layer.
• Meteors burn up in the mesosphere.

Thermosphere

• The thermosphere extends from the top of the mesosphere to about 500-1000 km altitude.
• Temperature increases with altitude due to absorption of high-energy solar radiation.
• The International Space Station orbits in the thermosphere.

Exosphere

• The exosphere is the outermost layer of the atmosphere, gradually fading into space.
• It extends from the top of the thermosphere outwards.
• Gases are very sparse in this layer.

Atmospheric Pressure

• Atmospheric pressure is the force exerted by the weight of the air above a given point.
• Pressure decreases with altitude.
• It's measured using a barometer.

Atmospheric Temperature

• Temperature variations within the atmosphere are caused by differences in solar absorption.
• Temperature changes with altitude in each layer of the atmosphere.

Greenhouse Effect

• The greenhouse effect is the process by which certain gases in the atmosphere trap heat and warm the planet.
• Greenhouse gases include carbon dioxide, methane, and water vapor.

Importance of the Atmosphere

• The atmosphere provides breathable air for living organisms.
• It protects the Earth from harmful solar radiation.
• It helps regulate Earth's temperature.
• It is essential for the water cycle and weather patterns.

Explore Earth's atmosphere, its composition of nitrogen, oxygen, and other gases, and its division into layers like the troposphere and stratosphere. Understand temperature variations and weather phenomena within these layers. Learn about the characteristics of each layer.