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CLIMATE/EARTH 401�Geophysical Fluid Dynamics�Dynamical Meteorology

Richard B. Rood

rbrood@umich.edu

https://clasp.engin.umich.edu/people/richard-b-rood/

https://openclimate.org/

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Conservation of thermodynamic energy

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Heat and work

Thermodynamics connects heat and work.

Heat and work are both forms of energy.
Heat is related to temperature, and can be thought of as the energy transfer associated with temperature change.

Temperature is related to motion of the molecules that make up a substance.

Work is “mechanical,” related to an object moving some distance.

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Conservation of Energy: The thermodynamic equation

First law of thermodynamics:

Change in internal energy is equal to the difference between the heat added to the system and the work done by the system.
Internal energy is due to the kinetic energy of the molecules (temperature)

Total thermodynamic energy is the internal energy plus the energy due to the parcel moving

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Mathematical Form

The mathematical representation follows from the first law of thermodynamics which is stated as: The increase in internal energy of a closed system is equal to the difference of the heat supplied to the system and the work done by it.

Many meteorological texts start with the enthalpy form of the first law of thermodynamics, where enthalpy is the total energy of a thermodynamic system. For a closed system this is written as

Where h is enthalpy, s is entropy.

T is temperature, p is pressure, α is specific volume