Met 421 Exam 1 Flashcards
Scale Analysis
W = 10 ^-2 m/s U = 10 m/s L = 10 ^ 6 m F = 10 ^ -4
3 characteristics for Potential Temp
- Temp parcel would have if it was compressed or expanded to 1000mb
- Vertical temp profile related to static stability
- Helps locate fronts especially over uneven terrains
Potential Temp and Stability
Change in Pot. Temp over time
> 0 : Stable
= 0 : Neutral
< 0 : Unstable
Why does geostrophic veering wind require waa?
A veering geostrophic wind requires flow from warmer to colder thickness.
Veering
- Clockwise
- WAA
Backing
- Counter Clockwise
- CAA
Competing Effects of Rossby Waves
- Advection of relative vorticity moving system eastward
- Advection of planetary vorticity moving system westward.
What Causes Rossby Waves?
- Terrain
- Latent heat
- Advection
- Downstream development
Forecast Process
- Observe
- Analyze
- Diagnosis
- Prognosis
- Communicate
Why is subjective analysis important?
- Station data is very valuable in assessing current conditions
- Better locate locations of fronts and systems
Ingredient based forecasting for winter weather
- Forcing for ascent
- Moisture
- Instability
- Temperature
- Precipitation Efficiency
Methods of estimating vertical motion
- Divergence aloft
- Vertical temperature profile
What does QG theory do?
- Helps understand the 3-D synoptic scale weather systems
- Reveals how hydrostatic and geostrophic balance constrain and simplify atmospheric motions
- Physical insight into forcing of vertical motions
Assumptions for QG theory
- Rossby number less than 0.10
- Hydrostatic balance
- Horizaontally uniform static stability
Q-G Omega Equation Term A
- 3-D Laplacian of vertical motion
Q-G Omega Equation Term B
- Differential geostrophic vorticity advection by geostrophic wind
Q-G Omega Equation Term C
- Laplacian of temperature advection by geostrophic wind
What is the Q-G Omega equation telling us?
Vertical motion is a result of vorticity advection and thermal advection
Q-G Omega Upward Motion
Upward Motion
- Increasing PVA
- WAA
Q-G Omega Downward Motion
Downward Motion
- Increasing NVA
- CAA
Q-G Geopotential Tendency Equation: HEIGHT FALLS
Height Falls
- PVA
- Increasing WAA
Q-G Geopotential Tendency Equation HEIGHT RISES
Height Rises
- NVA
- Increasing CAA
Prognostic vs Diagnostic
Diagnostic
- Spatial distribution at a given time
- Vertical motion field
Prognostic
- Local rate of change with time
- Vorticity and Temperature advection
Vertical Motion (Rising air vs Sinking air)
Rising Air
- Clouds and Precip
Sinking Air
- Clear skies
Q Vectors
- Converging: Rising motion
- Diverging: Sinking motion
- Points toward warm air: Frontogenesis
- Parallel to isotherms/thickness: Thermal advection
