6.1.1—Atmosphere boundary

The atmosphere is a gaseous boundary coupled to Earth’s surface, not a solid lid; it supplies gases, pressure, energy regulation and radiation filtering.

Focus on exchanges with biosphere, hydrosphere and lithosphere: gases, particles, water and energy cross the boundary. Most weather and water vapour are in lower layers.

Evaporation moves water from ocean to atmosphere; precipitation returns it to the hydrosphere.

The atmosphere is coupled through ongoing flows and has no sharp solid edge.

Do not list functions without naming the exchange that supports life.