What Is Earth’s Atmosphere?
Earth’s atmosphere is a thin layer of gases held in place by gravity. Although it extends hundreds of kilometres into space, 99% of it lies within 30 km of Earth’s surface.
Without the atmosphere:
Liquid water would evaporate
Harmful radiation would reach the surface
Temperatures would swing wildly
The Layers of the Atmosphere
The atmosphere is divided into distinct layers:
Troposphere
Where weather occurs
Contains most air and water vapour
Stratosphere
Contains the ozone layer
Protects life from UV radiation
Mesosphere
Meteors burn up here
Thermosphere
Extremely hot but very thin
Home to the ISS
Exosphere
Gradual transition into space
Why the Atmosphere Is Vital
The atmosphere:
Blocks harmful radiation
Regulates climate
Enables flight and sound
Protects against meteoroid impacts
It is Earth’s primary defence against the harshness of space.
Key Takeaways
The atmosphere is thin but powerful
It protects life and enables spaceflight
Space begins where air becomes negligible