Mountain Waves Clouds .


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Mountain Waves & Clouds. Investigating the occurrence of cloud-producing mountain waves. Alistair Reid. What is a mountain wave?. Mountain (or Lee) Waves are formed by wind flowing over the ridge of a mountain: May extend for many km downwind May extend high into the atmosphere (60,000ft)
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Slide 1

´╗┐Mountain Waves & Clouds Investigating the event of cloud-creating mountain waves. Alistair Reid

Slide 2

What is a mountain wave? Mountain (or Lee) Waves are shaped by twist streaming over the edge of a mountain: May reach out for some km downwind May expand high into the environment (60,000ft) Vertically transverse waves: wavelength 4-20km.

Slide 3

Observation of Mountain Waves Fly an airplane into one! - in 1966 a mountain wave tore separated a Boeing 707 close Mt. Fuji in Japan. Take a gander at the cloud developments: Lenticular mists Rotor mists Pilatus "top" mists

Slide 4

New Zealand\'s Mountain Ranges Landcare Research pictures 4 times day by day from NOAA Satellite : http://satellite.landcareresearch.co.nz/noaa/I have hunt the documented pictures down mountain wave mists. They most usually happen at: Ruahine ranges Tararua ranges Southern Alps

Slide 5

Cap Clouds Willowy pilatus mists are frequently observed coming up the windward face of a mountain. Air is cooled as it is lifted up the mountain confront, more often than not at around 6 o Celsius for each km. At the point when the air cools to its dew point, the top cloud frames. ? Why don\'t we see ceaseless pilatus mists downwind of the mountain?

Slide 6

The Foehn Effect The foehn impact regularly makes mists suddenly stop after achieving the summit. every now and again showed by the Southern Alps: the Nor-West Arch. Air on the lee side of a mountain is: Warm The idle warmth from the buildup of air dampness makes the air hotter downwind (for similar elevation). Dry Condensation has effectively expelled a portion of the air\'s water.

Slide 7

What causes a mountain wave? 1. A wind is pushed up the substance of the mountain Must be inside 30 degrees of opposite to the mountain edge The wind must be solid: no less than 20-25 hitches (11-14ms - 1 ) In New Zealand, the winds are transcendently nor-westers. Thus we discover mountain wave mists from North-South edges.

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Buoyancy Waves Once the air is dislodged upwards, it will sway around its underlying height. A vertical air wave is known as a gravity wave. The temperature-height slope: The temperature of the air in the troposphere diminishes with elevation. Air temperature diminishes when air is dislodged upwards adiabatically (no warmth included). The nearby air must be steady to stand waves to happen.

Slide 9

Stability The troposphere is steady if: Adiabatic Lapse Rate Troposphere Temperature Gradient > In a steady air: When air is lifted adiabatically, it is cooler than the environment and sinks When air is brought down adiabatically, it is hotter than the environment and rises Each peak of a standing wave might be joined by a Lenticular Cloud .

Slide 10

Amplitude & Wavelength Observed wavelengths (from satellite information) extend from 4 to 20km - reliably around 15km over the Tararua ranges Main Wavelength elements: wind speed and environmental soundness A wavelength of 15km suggests a twist speed of approximately 30m/s (Beer\'s "Barometrical Waves") Main Amplitude variables: geography Wave plentifulness depends for the most part on the width of the edge, furthermore on tallness, height and wind speed (Scorer). Mountain waves can have reverberation with mountains put a whole number of wavelengths downwind from the source. (California)

Slide 11

Rotors If the adequacy of the mountain wave is sufficiently incredible, rotors may frame. A rotor is a discrete vortex. Rotor mists are not noticeable from satellite photos, as they happen underneath the lenticular mists over the gravity wave peaks. Rotor Clouds may frame at the rotor if the air is sufficiently damp.

Slide 12

Requirements The perceptions of mountain wave mists over New Zealand are predictable with the hypothetical conduct of wind current over a mountain. Expect mountain waves when: Wind is a solid breeze: 11-14 ms - 1 or more noteworthy The wind is blowing into the substance of a reasonable mountain edge The environment has a steady temperature slope Or a low flying machine breaks into little pieces Mountain wave mists will happen when the air is adequately damp.

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