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CLIMATE/EARTH 401�Geophysical Fluid Dynamics�Dynamical Meteorology��Thermal low

Richard B. Rood

rbrood@umich.edu

https://openclimate.org/

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Thermal low / sea breeze exercise

  • This is an exercise on the formation of a thermal low. How can we get for a low-pressure system at the surface?

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Reference materials

  • Continuity equation
  • Pressure gradient
  • Convergence and divergence

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Equations of motion in pressure coordinates�(plus hydrostatic and equation of state)

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Pressure surfaces: Constant on height surface

Earth’s surface

pressure surfaces

Height

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Introduction of warming

Earth’s surface

pressure surfaces

warming

Height

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Guiding questions

Earth’s surface

pressure surfaces

warming

Questions for class

  1. What happens to the pressure surfaces?
  2. What happens to vertical velocity?
  3. What happens to horizontal divergence?
  4. What happens to the surface pressure?
  5. What happens to the surface winds?
  6. What happens to the wind at the top of figure?

Height

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Let’s think about growing and decaying disturbances.

Mass continuity equation.

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Mathematical analysis

  • Using the mass continuity equation can you derive an expression for the change of surface pressure.