3: Thermodynamics
- Page ID
- 9546
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Recall from physics that kinetic energy relates to the motion of objects, while potential energy relates to the attraction between objects. These energies can apply on the macroscale — to large-scale objects consisting of many molecules. They can also apply on the microscale — to individual molecules, atoms, and subatomic particles. Energy on the microscale is known as internal energy, and a portion of internal energy is what we call heat.
Energy can change forms between kinetic, potential, and other energy types. It can also change scale. The conversion between microscale and macroscale energies was studied extensively during the industrial revolution to design better engines. This study is called thermodynamics. The field of thermodynamics also applies to the atmosphere. The microscale energy of heat can cause the macroscale motions we call winds. Microscale attractions enable water-vapor molecules to condense into macroscale cloud drops and rain. In this chapter, we will investigate the interplay between internal energy and macroscale effects in the atmosphere. First, focus on internal energy.
- 3.0: Homework Exercises
- This page provides an in-depth exploration of atmospheric thermodynamics and upper-air weather observations, encompassing exercises related to temperature profiles, heat calculations, and environmental effects on storm dynamics. It highlights key concepts such as temperature gradients, heat fluxes, and the impact of moisture on atmospheric stability.
- 3.1: Internal Energy
- This page explains internal energy in thermodynamics, focusing on microscopic kinetic and potential energies. It covers sensible energy related to temperature and latent energy during phase changes. The text discusses energy transfer when heating water without temperature change and introduces key concepts like latent heat and specific heat, which are essential for understanding energy changes in materials.
- 3.2: First Law of Thermodynamics
- This page covers the principles of thermal energy transfer in air, linking it to the First Law of Thermodynamics, and differentiates specific heat concepts (Cp and Cv). It explains how thermal energy affects temperature and pressure under fixed volume and constant pressure conditions, highlighting Cp's role in atmospheric scenarios. Key equations for energy changes concerning temperature and pressure are provided, along with practical applications for heat transfer calculations in air systems.
- 3.3: Frameworks
- This page explores two thermodynamic frameworks: Eulerian, focused on fixed locations for analyzing wind effects, and Lagrangian, which moves with air parcels to study dynamics like temperature and moisture changes. It highlights the challenges posed by turbulence affecting air parcel mixing and underscores the significance of these frameworks in analyzing atmospheric processes and constructing budget equations.
- 3.4: Heat Budget of an Unsaturated Air Parcel
- This chapter covers the thermal processes of dry, unsaturated air parcels, outlining the Lagrangian form of the First Law of Thermodynamics and discussing lapse rates. It introduces the dry adiabatic lapse rate and examines heat transfer processes affecting buoyancy and storm development. Further, it explores the ideal gas law's application in deriving pressure and temperature relationships in adiabatic processes, emphasizing potential temperature for evaluating stability.
- 3.5: Heat Budget at a Fixed Location
- This page covers the Eulerian form of the First Law of Thermodynamics, focusing on heat flux impacts on temperature changes within a fixed volume of air. It explains various heat transfer mechanisms including conduction, advection, and turbulence, with equations for analyzing temperature changes. The pages also discuss the role of atmospheric turbulence in distributing heat, the dynamics of thunderstorms affecting heat flux, and the Eulerian net heat budget for forecasting temperature variations.
- 3.6: Heat Budget at Earth's Surface
- This page explains the heat budget at the Earth's surface, emphasizing the balance of heat fluxes (net radiation, sensible heat, latent heat, and conductive heat). It introduces the Bowen ratio to relate sensible and latent heat, with variations by climate. Additionally, it details calculations for surface fluxes, including turning latent heat into water-vapor fluxes and using field data to illustrate the determination of dynamic fluxes.
- 3.7: Apparent Temperature Indices
- This page explains how warm-blooded animals, including humans, maintain a core temperature of about 37°C through metabolism and environmental heat transfer. It discusses apparent temperatures, including the wind-chill index and the humidex/heat index, which evaluate perceived temperature based on wind and humidity.
- 3.8: Temperature Sensors
- This page covers various temperature sensors, including traditional liquid-in-glass thermometers (mercury and alcohol), bimetallic strips, wax-based systems, and electronic sensors such as thermistors and thermocouples. It also highlights advanced technologies like sonic thermometers and infrared sensors, which utilize sound speed and radiation emission for temperature measurement, along with satellite remote sensors that assess atmospheric temperatures through radiation emissions.
- 3.9: Review
- This page explains three heat budget types: a surface heat balance focusing on equating sunlight and radiation fluxes; an Eulerian budget assessing heat storage in fixed air volumes with influences from advection and turbulence; and a Lagrangian budget tracking temperature changes in air parcels, highlighting adiabatic cooling during ascent. Mastery of these concepts is essential for understanding atmospheric phenomena, including turbulence and storms.
Thumbnail: A constant pressure balloon stays aloft for weeks at an altitude of 100,000 ft so that the instruments in the attached gondola can make long-term measurements. Credit: National Scientific Balloon Facility, Palestine TX.