1 / 45

Homework Assignments for Atmospheric Science Course

This collection of homework assignments covers topics such as anelasticity, Boussinesq approximation, CAPE, Skew-T Diagrams, density currents, severe weather forecasting, and turbulent heat and moisture fluxes.

galbraith
Télécharger la présentation

Homework Assignments for Atmospheric Science Course

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. Homework 1.1 anelastic: …eliminates sound waves …eliminates prognostic P Boussinesque: …shallow flow …density perturbations are small but... retained

  2. Homework 1.2b Assume steady state, p’ small, u,v =0…

  3. Homework 1.2a CAPE=1000 j/kg Wmax=45 ms-1 CAPE=5000 j/kg Wmax=100 ms-1 Qr = 10 g/kg over 6 km Q-CAPE = 1200 j/kg

  4. Homework 1.2b Example Skew-T Diagrams Central U.S. Warm-Season Oceanic Tropical • Characteristics (CAPE=2750 J/kg, CIN=110 J/Kg): • Moderate PBL RH • Stable layer above PBL • Steep midtropospheric lapse rate (very unstable) • Characteristics (CAPE=1000 J/kg, CIN=10 J/Kg): • High PBL RH • No stable layer above PBL • Nearly moist-neutral lapse rate (slightly unstable) LIttle lifting required Deep lifting required

  5. Homework 1.3a Density Current Theoretical speed of propagation: 

  6. Homework 1.3a 2 hPa -4 K 1500 m 20 ms-1

  7. Homework 1.3b DCAPE Potentially coldest air in a cold pool descends from the level of minimum ThetaE

  8. Severe Weather Forecasting

  9. Severe Weather Forecasting S S T …Stability …Shear …Trigger

  10. "Low-level Jet"

  11. Source: Bluestein (1993)

  12. Severe Weather Composites

  13. Bluestein (1993)

  14. Sounding Types:

  15. Example Skew-T Diagrams Central U.S. Warm-Season Oceanic Tropical • Characteristics (CAPE=2750 J/kg, CIN=110 J/Kg): • Moderate PBL RH • Stable layer above PBL • Steep midtropospheric lapse rate (very unstable) • Characteristics (CAPE=1000 J/kg, CIN=10 J/Kg): • High PBL RH • No stable layer above PBL • Nearly moist-neutral lapse rate (slightly unstable) LIttle lifting required Deep lifting required

  16. Source: Bluestein (1993)

  17. Source: Bluestein (1993)

  18. Some Other Examples Western U.S. Warm Season Central U.S. “Elevated” Instability • Deep, dry PBL with moist midlevels • Strong downdraft, wind potential, little rain • Most unstable air with little CIN located above PBL • Common at night and north of warm/stationary fronts

  19. Sounding Evolution!!!!!!!!!!

  20. Lapse Rate Tendency Equation differential horizontal advection differential vertical motion differential diabatic forcing

  21. Turbulent Heat and Moisture Fluxes • PBL growth depends on several • factors including: • vigor of turbulent eddies • stability of air above PBL Daytime heating results in increase of PBL depth and potential temperature

  22. Turbulent Heat and Moisture Fluxes (Cont.) • In quiescent conditions the vertical moisture flux convergence < 0 • term can be critical • Unlike q, qv decreases above PBL • When not balanced by surface • evaporation or moisture advection, • as PBL grows qv can decrease • significantly due to vertical flux term • Large temporal decreases most • common when dry air exists above • PBL and inversion is not too strong In this example vertical heat flux convergence > 0 in PBL helps eliminate CIN but the strong drying from vertical moisture flux reduces PBL CAPE

  23. Turbulent Heat and Moisture Fluxes (Cont.) • Different Example (Day Before, Same Location and Quiescent Synoptic Condition) • Stronger initial inversion and moister • conditions above the PBL than • previous example • No temporal drop in PBL qv In this example, the heating/vertical mixing process also reduces CIN but this time results in increased PBL CAPE

  24. Effects of Layer Lifting on Potentially Unstable Sounding • Initial Sounding: • No CAPE for any parcels • Final Sounding: • Deep Moist Absolutely • Unstable Layer (MAUL) • Positive CAPE w/ no CIN Layer Lifting From Bryan and Fritsch (2000, BAMS)

  25. Moisture Tendency Equation mean advection eddy flux convergence diabatic sources

More Related