1. AIR MASS SOURCE REGIONS
Form in Areas with light or no winds
Quantico USMC 1

2. Conceptual Model 2

4. Midlatitude Cyclone Circulations: Patterns and Processes
Figure from Global Atmospheric Circulations, by R. Grotjahn
Note rotation about horizontal axis. Cold (warm) air sinking (rising) along isentropic surfaces  thermally direct circulation ( From Prof. Murphree Modern Climatology MR 3610) 4

5. (temperature advection occuring)
Baroclinic Flow
(temperature advection occuring)
and
Barotropic Flow
(no temperature advection occuring)
Baroclinic Flow
alters height field at top of page 5

6. Veering and Backing Winds
Thermal wind always points parallel to lines of constant thickness with lower thicknesses to the left
Thermal wind always has the colder air to the left
Veering winds turn clockwise with height and are associated with warm air advection (WAA)
Backing winds turn counterclockwise with height and are associated with cold air advection (CAA)
CAA
WAA

8. 8

9. 9

10. May 15,2008
Jet Max Wind
04W Tropical Depression Matmo 10

11. Ageostrophic Winds wrt Curvature
Supergeostrtophic Subgeostrophic Supergeostrophic
The along-stream component of the ageostrophic wind produces patterns of divergence and convergence due to curvature in the flow. Thus, a short wavelength between an amplified trough and downstream ridge usually results in strong upper-level divergence and vertical motion.
WFO SOO T. Funk

12. With Jets and Curvature
Ageostrophic, Divergent, and Vertical Motions Associated
With Jets and Curvature

13. From Jet and curvature ageostrophic flows
Low level convergence leads to upper level vorticity &
Positive vorticity advection (PVA) 13

14. Developing Wave Cyclone
Mid-latitude cyclones are "deep" pressure systems extending from the surface to tropopause level
recall that they are an example of a "cold core low“
For the storm to develop and grow, it can NOT be vertically "stacked"

15. 15

16. Life Cycle Birth Growth Mature Decay Examples
Open Wave Occluded Cut-off and fill
Examples 16

17. Recommended reading http://www. wpc. ncep. noaa

18. 8. Look at low level (1000mb) relative vorticity to view the wind directional/speed change at a front. 18

19. 19

20. typically less stable air warm front
Forced Lifting – Frontal
cold front
steeper slope
typically less stable air
warm front
more gradual slope typically more stable air
DLA Fig. 5.23

21. 0 C Conduction Convection Temperature Advection Latent Heating
Adiabatic (heating-cooling)
Radiative Heat Transfer
0 C 21

22. thermally direct circulation:  warm air rising/cold air sinking
Ageostrophic, Divergent, and Vertical Motions Associated With Jets
at jet entrance
at jet exit
thermally direct circulation:
 warm air rising/cold air sinking
 conversion of APE to KE
thermally indirect circulation:
 warm air sinking/cold air rising
 conversion of KE to APE

23. vertical motion & diabatic processes
layer
perspective
parcel
perspective

24. Parcel does not exchange heat with its surroundings
Conduction
Convection
Temperature Advection
Latent Heating
Adiabatic (heating-cooling)
Radiative Heat Transfer
Latent Heat release
Atm Avg Lapse rate ~6.5 °C/km
Expansion cooling  Compression warming
Parcel does not exchange heat with its surroundings 24

25. change in mass distribution
Big Six Equations of Atmospheric Dynamics
These figures, which I call triangle diagrams, show schematically the highly complex, nonlinear relationships between energy, mass, and momentum in the climate system that are described by the big six equations.
We usually think of these relationships in terms of T changes causing changes in mass distributions, which then cause changes in the winds. But the changes can also go in the other direction due to nonlinear feedbacks. For example, mass redistributions can cause T changes. And wind changes can advect mass and T, and thereby lead to T and mass changes.
change in mass distribution
= change in , p
change in T
change in wind
= change in V T
, p V
(1-3) x, y, & z Momentum equations (parcels u,v,w)
( 4 ) Continuity equation (parcels Density)
( 5 ) Thermodynamic Energy Equation (parcels Temperature)
( 6 ) Equation of State (relates parcels T, Density, and Pressure)
Slide From Prof Tom Murphree’s MR3610 Modern Climatology Course 25

26. 26

27. http://www. newmediastudio 27

28. Thickness (ΔZ) of a layer between 2 pressure surfaces is also proportional to the mean virtual temperature of that layer
Cold air is more dense, therefore thinner
Warm air is less dense, therefore thicker
Temperature is the only factor that changes the thickness of a layer
When you have a temperature contrast, you create height variations for a layer
Height variation create a pressure gradient
Pressure gradient creates a PGF
The change in the Geostrophic Wind with height is directly proportional to the horizontal temperature gradient
This is the Thermal (temperature) Wind relationship

29. Hypsometric Equation Derived from the hydrostatic equation
Implies that the thickness of a layer is directly proportional to the mean virtual temperature of the layer
Write up hydrostatic equation and hypsometric equation. Discuss. Derivation below (DO NOT DERIVE in class, just for Ref.)
Thickness calculation in most Met tools (eg. GARP) 29

30. Why Jet Streams Exist
We have already qualitatively discussed how T / density / pressure /wind relationships can explain the presence of a jet stream  large horizontal temperature / density gradients produce large height and pressure gradients and, thus strong winds. We now have the tools to do so quantitatively:
Hyspometric Equation: relates the mean T of a layer to the thickness and GPE. Helps to explain the creation of large height/pressure gradients in the upper-troposphere
Thermal Wind Equation: relates the horizontal T structure to the vertical wind shear of the geostrophic wind. Helps to explain the increase in wind speed with height in the troposphere, the jet max at the tropopause, and the subsequent decrease above the tropopause
Geostrophic Balance: relates the PGF to wind speed and direction. Helps to explain the jet max at tropopause level and the tendency for westerlies in the midlatitudes

31. Vg L H Hypsometric Eq. PGF T  Δp Thermal Wind Eq. Δp
Why Jet Streams Exist Vg
Hypsometric Eq.
T  Δp
PGF L H
Thermal Wind Eq. Δp
Geostrophic Balance
PGF  Vg Δp Vg

32. Move into colder surface temperatures Shear off upper warm core
Tropical Cyclone
Cold Core Low
Div
Jet H
Warm Core Low
Move into colder surface temperatures
Shear off upper warm core
Halby Hints 32

33. Ageostrophic Winds wrt Jet Streaks
---300mb heights
- - Isotachs
The cross-stream component of the ageostrophic wind produces patterns of divergence and convergence due to accelerations (jet entrance regions) and decelerations (jet exit regions) in the flow. The stronger the along-stream wind variation in the flow, the greater the upper-level divergence due to this component. Superimposing jet streaks and curvature enhances upper-level divergence in right entrance and left exit regions. WFO SOO T. Funk

34. Backing Cold advection
Veering Warm Advection O O
WAA
CAA
850mb T