How are lee waves formed?

How are lee waves formed?

Lee waves are standing waves in the air that form downwind of a hill or mountain range as winds pass over them.

How do mountain lee waves form?

Lee waves occur most often when a deep airstream with stronger winds in the higher levels and stably stratified air in the lower levels flows across a long ridge having a steep lee slope. The strongest up current then occurs not over the wind-facing slope but at the front of the first lee wave.

How far can mountain wave turbulence go?

Strong lift and Clear Air Turbulence may extend up to 100,000 ft. Vertically-propagating waves with sufficient amplitude may break, and result in severe Clear Air Turbulence between 20,000 and 40,000 feet.

What is a mountain lee?

The leeward—or “lee”—side is the one sheltered from the wind by the reference point. Windward and leeward aren’t frivolous terms. When applied to mountains, they are important factors in weather and climate—one is responsible for enhancing precipitation in the vicinity of mountain ranges, while the other withholds it.

What is a lee cloud?

Lee Wave Clouds, which are characterised by narrow middle level cloud bands perpendicular to the wind direction and parallel to the mountain chain. The length of the wave varies in range from about 3 – 40 km.

How are rotors formed?

Rotor clouds form at lowest levels and are a form of lee eddy. The air in the cloud rotates around an axis parallel to the mountain range. These clouds are associated with severe turbulence and strong vertical motions. At the bottom of the rotor cloud the wind direction is opposite to the gradient wind.

Which type of cloud would indicate mountain lee wave turbulence?

lenticular cloud
The most distinctive characteristic of the mountain wave is the lenticular cloud. This is a “signpost in the sky” indicating that mountain wave activity is present.

Where is the most severe turbulence in a thunderstorm?

Maximum turbulence usually occurs near the mid-level of the storm, between 12,000 and 20,000 feet and is most severe in clouds of the greatest vertical development. Severe turbulence is present not just within the cloud.

What side of the mountain is the leeward?

The leeward side is the side of the mountain that is downwind. There is less wind on this side because it is blocked by the mountain on the other side. The leeward side of a mountain is usually dry compared to the windward side.

What is a mountain wave in aviation?

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.

What are rotors winds?

A rotor (cloud) is a closed, vertical circulation that develops in the lee of high mountain barriers, or in the valley between two mountain ranges, when conditions are appropriate. The rotor is a form of lee eddy. At the surface the wind is in the opposite direction to the gradient wind.

How does a rotor work?

Rotors work hand-in-hand with brake pads to stop your vehicle. When you step on your brake pedal, your vehicle’s brake pads are compressed against the rotor creating friction. This friction enables your vehicle to stop while also creating a tremendous amount of heat. Rotors consist of two iron discs connected by ribs.

What clouds have the greatest turbulence?

Although towering cumulus clouds are indications of great turbulence, the greatest turbulence is created by cumulonimbus clouds. Thunderstorms are produced from the development of cumulonimbus clouds through stages. The first stage is the cumulus stage, characterized by continuous updrafts.

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.

Why is it called leeward?

Origin of the name The name of this island group, Leeward Islands, dates from previous centuries, when sailing ships were the sole form of transportation across the Atlantic Ocean. In sailing terminology, ‘windward’ means towards the source of the wind (upwind), while ‘leeward’ is the opposite direction (downwind).

Is leeward east or west?

In general, the north and/or east sides of each Hawaiian Island tend to have the windward climate. In contrast, the south and/or west sides of the islands are leeward.

Where is clear air turbulence strongest?

Any CAT is strongest on the cold side of the jet stream where the wind shear is greatest. In the vicinity of a jet stream, CAT can be encountered anywhere from 7,000 feet below to about 3,000 feet above the tropopause.