American Meteorological Society Certification Atmospheric Dynamics 2 — Questions and Answers
Question 1: What is the thermal wind relationship?
- Wind speed at the surface equals wind speed aloft
- Vertical wind shear is related to horizontal temperature gradients (Correct answer)
- Temperature increases with height in the stratosphere
- Wind direction rotates clockwise with height in all situations
Correct answer: Vertical wind shear is related to horizontal temperature gradients
The thermal wind relationship states that vertical wind shear in geostrophic flow is proportional to horizontal temperature gradients.
Question 2: Which flow regime is characterized by a small Rossby number and quasi-geostrophic balance?
- Microscale turbulence
- Synoptic-scale flow (Correct answer)
- Thunderstorm updrafts
- Sea breezes
Correct answer: Synoptic-scale flow
Synoptic-scale systems have small Rossby numbers, making quasi-geostrophic balance a good approximation.
Question 3: What does divergence in the upper atmosphere typically indicate at the surface?
- Surface high pressure
- Surface low pressure and rising motion (Correct answer)
- No surface weather
- Stable air mass
Correct answer: Surface low pressure and rising motion
Upper-level divergence removes mass from a column, lowering surface pressure and promoting rising motion.
Question 4: What is the primary driving mechanism for the jet stream?
- Ocean currents
- Horizontal temperature gradients in the troposphere (Correct answer)
- Stratospheric ozone heating
- Surface friction
Correct answer: Horizontal temperature gradients in the troposphere
The jet stream is driven by strong horizontal temperature gradients, particularly between polar and tropical air masses.
Question 5: In ageostrophic wind theory, what causes air to deviate from pure geostrophic flow?
- Constant pressure gradient
- Acceleration, friction, and curvature effects (Correct answer)
- Constant Coriolis parameter
- No temperature gradients
Correct answer: Acceleration, friction, and curvature effects
Ageostrophic motions arise from accelerations, friction, and curvature terms not captured by pure geostrophic balance.
Question 6: The omega equation in quasi-geostrophic theory diagnoses which atmospheric variable?
- Surface temperature
- Vertical motion (pressure velocity) (Correct answer)
- Specific humidity
- Potential vorticity
Correct answer: Vertical motion (pressure velocity)
The omega equation relates vertical motion (ω = dp/dt) to vorticity advection and temperature advection.
American Meteorological Society Certification Atmospheric Dynamics 2
What is the thermal wind relationship?