- 1 What are mountain waves?
- 2 How are mountain waves caused?
- 3 How high is a mountain wave?
- 4 What are mountain wave winds?
- 5 What is a mountain wave cloud?
- 6 How are clouds divided into four families?
- 7 Can you fly through lenticular clouds?
- 8 What causes mountain wave turbulence?
- 9 What is the lee of a mountain?
- 10 Are rotor clouds dangerous?
- 11 What is Lee effect lifting?
- 12 How does a trapped lee wave change with height?
- 13 What is severe mountain wave?
- 14 What is mechanical turbulence?
- 15 What is convective turbulence?
What are mountain waves?
Mountain Waves is defined as oscillations to the lee side (downwind) of high ground resulting from the disturbance in the horizontal air flow caused by the high ground.
How are mountain waves caused?
Mountain wave forms when strong winds blow across a mountain range, causing a wave-like pattern and extending for up to hundreds of miles downwind of the mountain range.
How high is a mountain wave?
Most often it extends anywhere from ground level to mountaintop level, but is frequently observed up to 35,000 feet. Destructive turbulence from the rotor rarely exists more than 2,000-3,000 feet above mountaintop level.
What are mountain wave winds?
Mountain waves are typically observed near large mountain ranges around the world when the large-scale winds are perpendicular to the mountain ranges. These mountain waves can produce very strong wind gusts in a narrow area along the foothills, and can also create strong turbulence which adversely affects aviation.
What is a mountain wave cloud?
An atmospheric gravity wave, formed when stable air flow passes over a mountain or mountain barrier. When sufficient moisture is present in the upstream flow, vertically propagating mountain waves produce interesting cloud forms, including altocumulus standing lenticular (ACSL) and other foehn clouds.
How are clouds divided into four families?
Clouds are divided into four families according to their height range: low, middle, high, and clouds with extensive vertical development. Clouds formed by vertical currents (unstable) are cumulus (heap) and are billowy in appearance.
Can you fly through lenticular clouds?
Atmospheric waves generate turbulence, so pilots avoid flying near lenticular clouds.
What causes mountain wave turbulence?
These waves are generated when strong winds flowing toward mountains in a generally perpendicular fashion are raised up over the mountains. As the winds rise, they may encounter a strong inversion or stable air barrier over the mountains that causes the winds to be redirected toward the surface.
What is the lee of a mountain?
The term leeward, or lee, refers to slopes that are oriented away from the wind. If winds are strong enough, snow from windward slopes can be redistributed or blown to leeward areas, causing them to become loaded. Wind slabs often form on lee aspects as a result of this wind transport.
Are rotor clouds dangerous?
They are associated with violent turbulence that can break wings off of aircraft, and their strong up- and down-drafts can cause pilots of small aircraft to crash while attempting to land and take off.
What is Lee effect lifting?
In meteorology, lee waves are atmospheric stationary waves. They are periodic changes of atmospheric pressure, temperature and orthometric height in a current of air caused by vertical displacement, for example orographic lift when the wind blows over a mountain or mountain range.
How does a trapped lee wave change with height?
Trapped And Vertically Propagating Lee Waves Trapped waves occur when wind speed above the mountain increases sharply with height and when stability decreases in the layer just above the mountain top. As the wave energy is trapped within the stable layer, these waves can propagate far downwind of the mountain crest.
What is severe mountain wave?
Mountain waves are defined as ‘ severe ‘ when the associated downdrafts exceed 600 ft/min and/or severe turbulence is observed or forecast. ‘Breaking waves ‘ and ‘rotors’ associated with mountain waves are among the more hazardous phenomenon that pilots can experience.
What is mechanical turbulence?
Mechanical Turbulence – LLT that results when airflow is hindered by surface friction or an obstruction. It occurs because friction slows the wind in the lowest layers causing the air to turn over in turbulent eddies which can cause fluctuations in winds and vertical velocities.
What is convective turbulence?
Turbulence occurring in convective storms, particularly thunderstorms, that is felt by aircraft. The turbulence is caused by strong updrafts and downdrafts.