Abstract
The impact of water vapor on the production of kinetic energy in the atmosphere is discussed here by comparing two idealized heat engines: the Carnot cycle and the steam cycle. A steam cycle transports water from a warm moist source to a colder dryer sink. It acts as a heat engine in which the energy source is the latent heat of evaporation. It is shown here that the amount of work produced by a steam cycle depends on relative humidity and is always less than that produced by the corresponding Carnot cycle. The Carnot and steam cycles can be combined into a mixed cycle that is forced by both sensible and latent heating at the warm source. The work performed depends on four parameters: the total energy transport; the temperature difference between the energy source and sink; the Bowen ratio, which measures the partitioning between the sensible and latent heat transports; and the relative humidity of the atmosphere. The role of relative humidity on the work produced by a steam cycle is discussed in terms of the Gibbs free energy and in terms of the internal entropy production.
Original language | English (US) |
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Pages (from-to) | 91-102 |
Number of pages | 12 |
Journal | Journal of the Atmospheric Sciences |
Volume | 68 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2011 |
Keywords
- Energy transport
- Hydrologic cycle
- Kinetic energy
- Latent heating/cooling
- Thermodynamics
- Water vapor
ASJC Scopus subject areas
- Atmospheric Science