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XWuffo

Wave lift visible in clouds ?

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I took these pictures near Lanseria Airport (FALA) this past Saturday. The temperature was 30deg C
and the wind was gusting in excess of 50Km/hour.
(That's 86F and 31mph for you Poms & Yankee's) This is the only time I have ever "seen" what appears to be wave lift displayed in the cumulus formations. Any weather/cloud experts out there care to comment ? The formation was visible right across the sky and quite awsome I might addB|

Oh yes, I was sure glad not to be up there with anything above me that represented a canopy/wing of any sortB|

As we in Africa know - "If you're going to be dumb - you'd better be tough."
- Tonto

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I am a meteorologist... Nice pics!!!!

I have never heard the term wave lift before, but I will explain what it appears to be.

It does appear to be a small scale gravity wave affecting the LCF (lifted condensation level). This is quite common when there is an inversion in the atmoshpere. Consider the top of the inversion like the surface of water. It will "wave" as these pictures suggest any time there is a disturbance in the stable layer below the inversion. Typically you will see this happen in the winter, but on occassions turbulence enduced convection (Cumulis clouds) may cause waves in the stable layer. It is fairly rare however, because it is difficult for convection to occur in a stable atmosphere.

There must have been some VERY cold air aloft above the stable layer inorder to cause the Cum clouds to form.

I have seen this before, but like I said it is not very common except in mountainous areas where orographic lifting forces leewaves/gravity waves.

Chris

-----------------------------------------------------
Sometimes it is more important to protect LIFE than Liberty

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> I took these pictures near Lanseria Airport . . .

Is that airport near any mountains? Mountain waves are often indicated by lenticular or 'wave' clouds, and can be very dangerous for pilots. This month's AOPA-pilot has an incident report concerning inadvertent entry into a lenticular cloud and the resulting damage to the aircraft (he landed safely, fortunately.)

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Google and you shall receive.;)

http://azworldairports.com/airports/p2480hla.htm

Lanseria Airport, South Africa,



http://www.witsflyingclub.co.za/lanseria.htm
Quote

Lanseria International Airport, the home of Wits Flying Club, is located some 15 kms North of Johannesburg. The airport is located under the Johannesburg (ICAO designation: FAJS) TMA, South Africa's busiest airspace.

The major details of the airport are as follow:

* ICAO designation: FALA
* Variation: 17° W
* Elevation: 4517 feet
* Reference point: S25 56.4 E025 55.5


--"When I die, may I be surrounded by scattered chrome and burning gasoline."

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Is that airport near any mountains?
Quote

Yes, in fact, the wind would have come directly over the Magaliesburg Range, some 20 miles away, and then again over a secondary range of foothills, called Skurveberg (skew mountain) All those rolling hills must surely have contributed to this wave effect.

From what I learned in Paragliding, 'wave lift' is regularly used by glider pilots, to ride 100's of miles, by following this mostly invisible band of lift, just behind mountain ranges. The wind speed has to be rather strong for this effect to happen.

As we in Africa know - "If you're going to be dumb - you'd better be tough."
- Tonto

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Could someone please explain what I am supposed to see in the pictures? Maybe even draw some arrows like "Cold air here", "Wave propagating in this direction"? Sure, I see some big wavy thing, but can't quite connect it to the LCF or whatever.

Is a "gravity wave" like a wave in the ocean, or what is it?

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Wave lift is quite common down wind of large hills, mountain ranges, etc.
With the perfect combination of wind, humidity and temperature, you can see wave clouds, lenticular clouds or even roll clouds indicating the locations of wave lift.
Glider pilots love to fly in wave lift.
My experience with wave lift occurred 10 miles downwind of the Tehachapi Mountians, over the Mojave Desert, near California City. I flew too close to a cloud and got "stuck" in a 1,000 feet per minute up draft! The only way to get my clunky tandem canopy out of the wave lift was to spiral until my student vomited!
A few miles (kilometers) North of the Mojave Desert - in the Owens Valley - glider pilots have set world altitude records (better than 30,000 feet) riding the Tehachapi Wave.

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