1 / 11

Thermodynamics of the Atmosphere

Physics. Meterology. R varies with gas. Thermodynamics of the Atmosphere. Atmosphere contains N 2 + O 2 + Ar + CO 2 ± H 2 O well mixed in turbosphere ideal gas (unless saturated). Ideal Gas. p. Ideal Gas. dz. p + dp. z=0. Hydrostatic Equation for an Isothermal Atmosphere.

zion
Télécharger la présentation

Thermodynamics of the Atmosphere

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Physics Meterology R varies with gas Thermodynamics of the Atmosphere • Atmosphere contains N2 + O2 + Ar + CO2 ± H2O • well mixed in turbosphere • ideal gas (unless saturated) Ideal Gas

  2. p Ideal Gas dz p+dp z=0 Hydrostatic Equation for an Isothermal Atmosphere

  3. p0/e p0/10 H10 H Scale Height H = RT/gis the (exponential) scale height Decade scale height H10= ln10 RT/g at 250 K H10=16.8 km at 280 K H10=18.9 km Scale height ~ thickness of troposphere  thicker troposphere at low latitudes, where air is warmer

  4. Atmospheric pressure profile

  5. Atmospheric layers • Troposphere • pressure drops from 1000 mbar to ~200 mbar,contains 80% mass • thickness 10 – 15 km • temperature drops with height by ~6.5 ºC/km,unstable as hot air rises! • well mixed: molecules travel up and down in few days • most weather in this layer, i.e. most heat transport • Tropopause • region of stable, isothermal air ~ 200 mbar • division between troposphere and stratosphere • top of “weather”

  6. Stratosphere • pressure from ~200 mb to ~1 mb, height 10 – 50 km • temperature increases with height (due to heating in ozone layer) •  stable air, isothermal strata with little mixing • stops weather extending upwards, so keeps water in atmosphere • temperature reaches maximum at Stratopause • Mesosphere • “middle atmosphere”, pressure 1 mb to 10-2 mb • temperature drops to lowest values ~ -90ºC • Mesopause is top of well mixed region, 99.9% of atmosphere below • Thermosphere • temperature increases rapidly (due to molecular dissociation) • v.large KE/molecule, but few molecules!  Feels cold • mean free path so large that no longer well mixed

  7. 1st law of thermodynamics dq=0for adiabatic (fast) processes Dry Adiabatic Lapse Rate (DALR) Saturated Adiabatic Lapse Rate (SALR) SALR < DALR since latent heat is released by water vapour

  8. Atmospheric stability Unstable if Conditionally stable if Stable if

More Related