Atmosphere Structure Key Concepts (Last-Minute Review)

Troposphere

  • Definition: Closest to Earth; highest air density; most weather (≈99%\approx 99\%);
  • Boundary: Tropopause.

Stratosphere

  • Location: Above troposphere.
  • Ozone layer: Shields life from ultraviolet (UV) radiation.
  • Temperature profile: Increases with altitude due to ozone absorbing UV energy.
  • Boundary: Stratopause.

Mesosphere

  • Density: Lower than troposphere/stratosphere.
  • Temperature profile: Decreases with altitude.
  • Boundary: Mesopause.

Thermosphere

  • Characteristics: Very low density; temperature rises with altitude.
  • Boundary: Thermopause.

Temperature structure across layers (summary)

  • Troposphere: Temperature decreases with height.
  • Stratosphere: Temperature increases with height.
  • Mesosphere: Temperature decreases with height.
  • Thermosphere: Temperature increases with height.

Layer suffixes and why layers exist

  • Suffix "-sphere" indicates a layered region.
  • Layers defined by changes in temperature with height.

Pauses (boundaries between layers)

  • Tropopause: Between troposphere and stratosphere.
  • Stratopause: Between stratosphere and mesosphere.
  • Mesopause: Between mesosphere and thermosphere.

Density and pressure with height

  • Atmospheric pressure decreases with altitude.
  • Heavier molecules dominate near surface; lighter gases at higher altitudes.

Ozone layer and UV protection

  • Located in the stratosphere.
  • Protects life by absorbing UV radiation.