ATOC 4720: class 16ATOC 4720: class 16

Entropy Entropy Generalized statement of the Second Generalized statement of the Second

Law of thermodynamicLaw of thermodynamic Atmospheric aerosolAtmospheric aerosol Effects on atmospheric phenomenaEffects on atmospheric phenomena

Carnot cycle: 4 stepsCarnot cycle: 4 steps

Begins at A

Q1

Q2

Heat is transferred from warmer (H) to colder (c) body

Efficiency:

Hot to cold:Heat can not by itself transfer from cold to hot

EntropyEntropy

The ratio Stays the same no matter

Which isotherm is chosen in passing from one adiabat to anotoher. Therefore,

Is a measureof the difference between the two adiabats; It is called the difference in Entropy (S).

We define:

As the increase in entropy S.Unit mass:

The first law of thermodynamics:

We can derive that:

Transformations in which the entropy remains constant (and therefore potential Temperature remains constant) are called Isentropic.

T-entropy (S) diagram T-entropy (S) diagram

Work done

Generalized statement of the second Generalized statement of the second law of thermodynamicslaw of thermodynamics

Up to now: ideal reversible, equilibrium

1. There exists a function of state for a body called entropy s;

2. S may change (due to thermal conduction) Or as internal change

3.

4. For reversible process

For nonreversible:

Reversible:

Nonreversible:

3. Aerosols3. Aerosols

Total concentrationTotal concentration

Size spectraSize spectra