Thinning Air

Exponential pressure

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Pressure is the weight of the air above.
• It falls exponentially: $P = P_0 e^{-h/H}$, with $H \approx 8$ km.
• Pressure halves roughly every 5.5 km.

Steps

1. A pile of air
2. Half an atmosphere
3. The top of the world
4. Ninety per cent below
5. At cruising altitude
6. Tea on Everest