Earth's Structures: Geosphere and Atmosphere

Introduction

Focus on two main structures:
- Geosphere: Geological layers of the Earth
- Atmosphere: Layers above the Earth
Aim: Describe the composition of these structures
Mention of four subsystems: Biosphere, Hydrosphere, Geosphere, Atmosphere

Troposphere:
- Lowest layer touching the Earth
- Most clouds and weather phenomena occur here
- Contains 75% of atmospheric mass and 99% of water
- Temperature decreases with altitude; tropopause is very cold (~-60°C)
- Extends about 11 miles from Earth’s surface
Stratosphere:
- Above the troposphere
- Temperature increases with altitude, hence 'stratified'
- Location for most commercial airplanes
- Contains the ozone layer, which protects from UV light
Mesosphere:
- Above stratosphere
- Temperature decreases with altitude, coldest atmospheric layer
- Where meteors burn up
Thermosphere:
- Above mesosphere
- Temperature increases, can reach 4500°C but feels cold due to low air density
- Home to the International Space Station
Exosphere:
- Outermost layer, merges with space
Bird Altitude:
- Most birds stay in the troposphere
- Rupel’s Griffon Vulture can reach into the stratosphere

Lithosphere:
- Includes crust and upper mantle
- Composed of tectonic plates (e.g., Pangaea)
Asthenosphere:
- Below lithosphere, rocks are soft but not liquid
- Acts as a lubricant for tectonic plates
Mantle:
- Mostly solid, very hot (up to 4000°C)
- High pressure prevents melting
Core:
- Outer Core: Liquid due to slightly lower pressure
- Inner Core: Solid, extreme pressure keeps it solid despite high temperatures
- The spinning of the inner core creates Earth’s magnetic field

Interface of troposphere (bottom of atmosphere) and lithosphere (top of geological layers)

Environmental Science: Understanding the environment
Environmental and Biodiversity Crises: Upcoming subject on issues facing the environment