Level 8: Winds of a planet

Air and fluids · level 8 of 8 · rough age 17 and beyond (a guide for parents; anyone can start anywhere)

The last level scales up from a rotor blade to a whole planet. You start with the Reynolds number, which says when viscosity matters and when flow turns turbulent, and find that Ingenuity's blades flew in air that behaves like syrup. Then you build up the physics of weather: winds driven by pressure differences, turned by the planet's spin, carried round in great circulations, and on Mars, whipped into dust storms that can cover the planet.

Lesson	You will be able to
The Reynolds number	Use \(Re = \rho v L/\mu\) to compare flows on Mars and on Earth
Laminar and turbulent	Use the Reynolds number to say whether a flow is smooth or turbulent
Pressure gradients	Find how fast a pressure difference speeds up the air
The Coriolis effect	Use \(f = 2\Omega \sin\varphi\) and find the geostrophic wind
Global winds	Explain the Hadley circulation and Mars's carbon dioxide flow
How dust storms grow	Explain the feedback that grows a dust storm, with a heating estimate

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