Meteorology 3000- Mountain Weather and Climate

Assignment 9. Due November 18. 10 points

These questions require you to review the material on the 3 COMET modules related to terrain forced circulations. I have indicated which module you are likely to find the question discussed (TFF, GAP, DOWN).

• 1. (TFF) 3 points. Choose all answers that apply. Air is most likely to be blocked by the topography when:
  • The stability is weak
  • The stability is strong
  • The wind speed is strong and the flow is directed towards the barrier
  • The wind speed is weak or the flow is directed parallel to the barrier
  • The terrain is high
  • The terrain is low
  • The Froude number is much less than 1
  • The Froude number is equal to 1
  • The Froude number is much greater than 1
  • The barrier is isolated
  • The barrier is elongated perpendicular to the flow direction
  • the kinetic energy of the flow approaching the obstacle is greater than its gravitational potential energy
  • the kinetic energy of the flow approaching the obstacle is less than its gravitational potential energy
  2. (GAP) With an idealized Venturi effect, where are winds typically strongest? Choose the best answer.
  • The gap entrance
  • The gap exit
  • The narrowest part of the gap
• 3. (GAP) Under typical gap flow conditions, where is low-level air the coolest? Choose the best answer.
  • Over the gap exit
  • Over the middle of the gap
  • Over the gap entrance
• 4. (GAP) Which of the following hazards may be associated with gap winds? Choose all that apply.
  • Freezing rain
  • Tornadoes
  • Wind shear
  • Flooding
  • High winds
  • Cold temperatures
• 5. (DOWN) Which of the following hazards are typically associated with mountain wave activity? Choose all that apply.
  • High winds
  • Heavy precipitation
  • Clear air turbulence
  • Fog / low stratus
• 6. (DOWN) The Chinook is a downslope wind that occurs at which of the following locations? Choose the best answer.
  • Austrian Alps
  • Croatia
  • Rocky Mountains
  • Southern California
• 7. (DOWN) Which of the following factors lead to warming caused by downslope winds? Choose all that apply.
  • Melting of frozen precipitation in the descending air
  • Dry adiabatic ascent and moist adiabatic descent
  • Moist adiabatic ascent and dry adiabatic descent
  • Disruption of the nighttime surface-based cold pool
  • Erosion and or displacement of an existing cold pool
  • Adiabatic compression of descending air
  • Upstream blocking of stable low-level flow
• 8. (DOWN) Answer the following using the Froude number calculator on page 3 of the Interactions page under Concepts. a. For the Rocky Mountains and a standard atmosphere, approximately what wind speed is required for a Froude number of 1? 15-20 m/s, 30-35 m/s or 45-50 m/s? b. For a U.S. standard atmosphere, a surface wind of 20 m/s will ascend a mountain of approximately what height? 1 km, 2 km, 3 km, 4km? c. If the atmosphere is isothermal, what wind speed is required to ascend the Appalchian Mountains? 15-20 m/s, 30-35 m/s, 45-50 m/s?