Lesson 6: Lenticular Clouds
 

Lenticular clouds seem to be the most popular ones people like to view so thought I would discuss what they are and how they form...

What are Lenticular clouds? They are the 'almond' shaped, 'UFO shaped', 'lens shaped' or 'Accordion shaped' clouds that sometimes form over mountainous or hilly areas…they are always a sign of wind shear at one or more elevations as the cloud is being 'sculpted' by the winds instead of developing into a 'standard' Altocumulus cloud.

Two useful links to supplement this info are:

Wiki Page for Lenticular clouds:

http://en.wikipedia.org/wiki/Lenticular_cloud

A second page with lots of good images of Lenticular Clouds:

Page with Great photos of Lenticular clouds

The way that they are formed is the same as for 'normal' clouds…the parcel of air is pushed up a geographic obstacle (also known as orographic lift) and as the air parcel is lifted it cools, expands and condenses…if this process is sufficient then it will form cloud…however, instead of just stopping there…the difference is that the winds are sufficiently high at one or more levels in the horizontal 'stream' to cause convergence and 'speed' the air flow up…thereby causing the shape of the cloud to become sculpted at that height to reflect the amount of wind compared to other heights…

I'm no artist (as you can plainly see) but I hope this helps to visualise what I am on about…trying to write freehand on a tablet is not my thing…

for example if the wind is very strong on the surface and at height but the middle region is 'normal' or slower then you get shearing of the cloud at the top and at the bottom (visualised below):

http://farm8.staticflickr.com/7126/7...8484516312.jpg
stronger flow at top and bottom creating almond shape by BA_pics, on Flickr

…if you have varying shear at different vertical heights you get the zig zag look that many associate with Lenticular clouds

http://farm8.staticflickr.com/7126/7...cb7009ca45.jpg
Varying Shear creating accordian shape by BA_pics, on Flickr

…and finally if you get the hollow bottom UFO look then this is a fairly uniform shear occurring from the converging flow over the mountain…and it sculpts the bottom of the cloud in an arc that follows the ridge of the mountain as well as shearing the top in a similar fashion but just allowing enough cloud development to look like a UFO…

http://farm8.staticflickr.com/7133/7...898c9b4834.jpg
Uniform Shear creating UFO cloud by BA_pics, on Flickr

What all of this means is that the way the cloud is sheared will tell you how strong the winds are aloft and where they are particularly strong compared to the remaining 'ambient' flow…

The shear can be dangerous if not detected by small or large aircraft as the winds could go from say x knots to y knots over a very short vertical space which would cause some or great stress and turbulence, which is why pilots will fly around or higher / lower if they can when they know and see such areas of wind shear over mountains...

Effectively the winds over such terrain act as local, isolated jets.

So the next time you see some Lenticular clouds you can point out the way the shear is happening and explain why this cloud looks the way it does…(if that person is still listening to you and hasn't simply walked off :eek:

Hope this is of interest, as always please do let me know if there are any questions.@:-):)

We have one that definitely needs explaining. Found it on a friend's FB page.

https://fbcdn-sphotos-a.akamaihd.net...66320644_n.jpg

Although, even though it look ominous it probably is simply a wall cloud like in this video.

EDIT: A Google picture search led me to the photographer's site. Some nice stuff there! http://bigstormpicture.com/

http://cdn.c.photoshelter.com/img-ge...0/IMG-8179.jpg

http://cdn.c.photoshelter.com/img-ge...0/IMG-9231.jpg

Great picture HB ^

"Simply a wall cloud" :eek::eek:

Wall clouds are ominous! Shelf Clouds as well...

It is indeed a wall or shelf cloud under the base of a massive Cumulonimbus...

Some great stuff to talk about with this one but not enough time given that I need to get a generous dose of Red into me before my flight in an hour or so...so will come back to this picture and theme tomorrow. ^ :D

Cloud Trip Report LHR - BOS BA 239 7th July 2012
 

Thought I would use my BA flight yesterday to post quite a few cloud photos of my own…Not nearly as exotic as many of the previous ones everyone else has posted, however, I hope they are still get the imagination going:

So starting at the CCR terrace I took a few pictures of the clouds and aircraft:

http://farm9.staticflickr.com/8162/7...28601568_c.jpg
CU with SC or AC at LHR by BA_pics, on Flickr

http://farm8.staticflickr.com/7264/7...033dcba4_z.jpg
Custard Comet by BA_pics, on Flickr

http://farm9.staticflickr.com/8014/7...25aa223c_z.jpg
Doves everywhere by BA_pics, on Flickr

Then all to quickly it was time to make my way to B35 for my departure...

As luck would have it my 777 dorm hell in CW and an aisle seat to boot turned out to be 3K in NF on G-VIIL with some smart tactics….

http://farm9.staticflickr.com/8290/7...0065c656_z.jpg
GVIIL with NF as my ride today by BA_pics, on Flickr

Down back there was a big school class and the flight was rammed…so very pleased with myself indeed and celebrating the great start to my trip with a glass of bubbly while a rain shower (aren't they rare lately :( ) comes down...

http://farm9.staticflickr.com/8426/7...404aa22d_z.jpg
Every good cloud report starts with fizz and RASH by BA_pics, on Flickr

The condition of the cabin was great, afterwards looked at the 777 thread guide and noticed she was only refitted this Spring...

http://farm8.staticflickr.com/7277/7...84b884c4_z.jpg
Proof of GVIIL above all that clutter by BA_pics, on Flickr

During taxiing, three BA flights were ahead of us and depending on how you looked out the window…looked like they were heading for each other :)

http://farm9.staticflickr.com/8156/7...7300b96e_z.jpg
Three tail fins on taxi by BA_pics, on Flickr

Okay, to the cloud report LHR - BOS BA 239 7th July 2012:

As we took off, there were rain showers from the Cumulus or Stratocumulus based clouds and light levels were quite poor...

http://farm9.staticflickr.com/8430/7...08a1b925_z.jpg
Climbing but not at base level yet SC by BA_pics, on Flickr

One that I never see people post as it is quite boring but still worthwhile…everything looks like fog when you are in cloud...

ihttp://farm8.staticflickr.com/7108/7...46b4d9e8_z.jpg
In Cloud so looks like fog by BA_pics, on Flickr

As we started to break through the cloud deck I love the feeling of going in and out of the cloud and the play of light and shadow on the tops...

http://farm8.staticflickr.com/7130/7...b57aa0f1_b.jpg
love the colour shading in this break in cloud by BA_pics, on Flickr

http://farm9.staticflickr.com/8157/7...9a425b36_b.jpg
breaks in Cloud show great SC tops by BA_pics, on Flickr

It may just be me but I think the CW or OF 3 windows set-up were better for viewing clouds when you were sat back in your seat…(still I am starting to become a fan of NF and am willing to use 'only' 1 window to look at clouds if need be ;)

http://farm8.staticflickr.com/7250/7...fc567608_z.jpg
NF 2 windows is just too wide to see in stereo by BA_pics, on Flickr

Some more cloud top photos...

http://farm9.staticflickr.com/8007/7...f67b72ef_c.jpg
lovely tops to deck of cloud by BA_pics, on Flickr

http://farm8.staticflickr.com/7256/7...bcba812c_b.jpg
such a turbulent world viewed from the tops by BA_pics, on Flickr

This one shows how the warmer air parcels are still expanding above the area where the tops of cloud are typically but also shows how the layer above the tops is less uniform and starts to make the cloud fibrous and spread out instead of being the nice cauliflower type Cumulus heads we expect...

http://farm8.staticflickr.com/7279/7...bf508a8a_b.jpg
expanding but not enough potential by BA_pics, on Flickr

For the life of me…I can't explain it…but when I saw this cloud shape with the hole in the middle I thought of Dr. Who stories….

http://farm8.staticflickr.com/7136/7...f960ef65_b.jpg
Dr Who cloud picture by BA_pics, on Flickr

And one for Prospero, showing the engine cowling….quite hard to do from 3K…but I made an effort and sat in the buddy seat to do this...

http://farm9.staticflickr.com/8293/7...b281c8ab_b.jpg
from 3k its hard to get the engines in a pic by BA_pics, on Flickr

Cloud report part 2:
 

As we continued to climb and get over Wales the SC/CU/AC deck became a more uniform AS cloud cover...

http://farm8.staticflickr.com/7257/7...8e617521_b.jpg
over Wales AS deck by BA_pics, on Flickr

Strangely I noticed the AS starting to break up and become convective broken CU...

http://farm9.staticflickr.com/8025/7...96e785a1_c.jpg
AS becomes scattered CU by BA_pics, on Flickr

I thought this must be related to geography and quickly turned on the AVOD and looked to see where we were…which seems to justify my thoughts as we were just leaving the Welsh coastline when the cloud cover broke up almost completely...

http://farm9.staticflickr.com/8431/7...c2613231_b.jpg
Cloud stops at coast line of wales by BA_pics, on Flickr

A span from the moving map to show where we were when I took the above pic.

http://farm8.staticflickr.com/7125/7...8b0a001b_z.jpg
moving map to show cloud change by BA_pics, on Flickr

Over Ireland the AC deck seemed to be back and very developed...

http://farm9.staticflickr.com/8021/7...6ae42297_b.jpg
AC Floccus from above by BA_pics, on Flickr

http://farm8.staticflickr.com/7126/7...459e09d2_b.jpg
large expanse of AC undulates from above by BA_pics, on Flickr

Then again, once we started to move back out over ocean…the cloud cover style changed…this time it was to a very large Cirrostratus over Altocumulus deck...

http://farm8.staticflickr.com/7258/7...72a700eb_b.jpg
start of CS at higher levels by BA_pics, on Flickr

I personally love the luminance of the clouds in the right light…this didn't come out very well in the photo but the CS at the top was almost mother of pearl looking at this time...

http://farm8.staticflickr.com/7251/7...c6f899a9_b.jpg
CS luminance above AC deck by BA_pics, on Flickr

Finally, my stomach got the better of me as well as a long day…so had some excellent food (see the Olympic thread for pics there) and grabbed about 3 hours of sleep...

When I lifted the blind on the window it was a very beautiful Sunset and there was nought a cloud in the sky except the distant high AC line in the distance...

http://farm8.staticflickr.com/7254/7...47b42b31_b.jpg
High AC in distance at sunset over BOS by BA_pics, on Flickr

We touched down about 7 hours after take off and I had to consciously try to wipe the smile off my face from an excellent flight and Cloudscape before approaching the US immigration officer…

Hope these pics bring some interest and intrigue you as much as they do me…

Let me know if there are any questions...:)

Good stuff BotB I especially liked the first cloud picture over Wales.

Day flights are great for gazing out of the window. ^

Pictures during climb, whatever next ;)

Lesson 7: Special Clouds, part I
 

So, time to come back to that great picture henkybaby posted a few weeks ago…

A great cloud picture indeed ^

So, what is this and how did it form?

Thanks to the link HB posted from the photographer…I see that the above picture is actually a close up of the panorama below:

http://farm8.staticflickr.com/7130/7...e4c5e022_b.jpg
Full shot of cloud Copyright Ryan McGinnis Bigstormpictures.com, on Flickr

Which helps us to see a few things (besides it being an awesome picture)…

The cloud is an almost circular or wedge shape in the horizontal plane and also that this cloud is at the leading edge of the storm itself (there is other cloud around that is also dark but the actual thunderstorm cell itself begins at around this point)…so this is a Shelf cloud and more generally known as an Arcus cloud.

What is a shelf or arcus cloud?

First, for all of these above cloud types we MUST have a Cumulonimbus as a starting point, although lightning and thunder are optional but usually also present. Precipitation will also definitely be occurring, but may only be limited to a specific area. A typical wind circulation for a CB cloud would look like this (assuming the CB is moving Left to Right in the diagram):

http://farm9.staticflickr.com/8143/7...26241c45d1.jpg
CB Wind Cycles by BA_pics, on Flickr

So, back to the original pictures, the clouds we see are ones that form below a thunderstorm (or convective clouds such as Cumulus). An Arcus cloud is simply a wedge shaped cloud that you see below a thunderstorm. A Shelf cloud is a type of Arcus cloud but is different to a Wall cloud…(a Roll cloud is also a type of Arcus cloud)

You can also see some other Arcus clouds on the wiki page here:

http://en.wikipedia.org/wiki/Arcus_cloud

Both a wall cloud and a shelf cloud can be signs of dangerous activity;

To elaborate, a bit about how they form and what they represent:

Shelf clouds: They form in the downdraft or outflow from a thunderstorm. The convective nature of the cloud means that while you have up and down drafts inside the cloud there is generally always a downdraft outflow at the leading edge of a thunderstorm …a simplified diagram is below:

http://farm8.staticflickr.com/7247/7...1fe7079c_z.jpg
Shelf Cloud diagram by BA_pics, on Flickr

So, in this case the outflow from the thunderstorm is very strong and called a gust front…it can produce its own clouds even a short distance from the storm but that is another story…so we get this very pronounced outflow of COLD air that proceeds the rainfall we associate with a thunderstorm and as this cold air moves over the surface it forces the (comparatively) warmer air it undercuts to rise and therefore cool slightly as well as mix with the cold air which saturates the area between the two and causes cloud…this cloud is attached to the base of the Cumulonimbus and can appear to be in 'bands' or 'rolls' looking like a wedge which indicate the varying wind speed at that height…although we are only talking about the area between the ground and the base of the CB cloud (roughly 800 m vertical usually) this can have strong wind shear as the flow direction and speed can vary significantly.

The top edge of the Shelf cloud is usually fairly smooth and uniform whereas the bottom can look very ragged and appear 'ripped' as we see in these photos…this indicates the very strong downdrafts that are blowing out from the storm and literally 'shearing' the cloud developing there…like a page being ripped in two…

The main difference between a Shelf and Wall cloud is that the Wall cloud is always at the back of the storm and indicates that a tornado or funnel cloud could form but is not associated with the gust front or leading edge of the storm and is not necessarily indicating a strong wind shear like a Shelf cloud.

Wall Clouds…

A Wall cloud forms (usually) near the back of the thunderstorm (and associated CB cloud)…this area is where a strong updraft occurs in the thunderstorm and represents one of my favourite meteorological terms (Entrainment)…

http://en.wikipedia.org/wiki/Entrainment_(meteorology)

Effectively, the rising warmer very moist air that is being sucked up into the thunderstorm mixes with the quite cool air inside the CB cloud and saturates this air as the temperature does not generally increase but the moisture content does causing cloud to form…The Wall cloud may or may not be attached to the base of the CB cloud but will always be below the CB cloud.

http://farm9.staticflickr.com/8145/7...bdf9f28a_z.jpg
Wall Cloud diagram by BA_pics, on Flickr

So, a Shelf cloud is seen at the front edge of a thunderstorm and is indicative of a very strong outflow wind and high wind shear at the base of the Cumulonimbus…

While a Wall Cloud is seen at the rear of the thunderstorm and usually means that a Tornado could form and that there is also some very serious winds and precipitation inside the Cumulonimbus.

Hope this is of interest…Thanks to henkybaby for posting the question. ^

Now, as it is the Summer break and many of you have flown off to different holiday destinations…I expect to see a few interesting cloud or weather pics posted soon from your travels! :)

P.S. I can't believe we let the BA Cloud thread slip to page 21 on the forum :eek:

Hope everyone has a great weekend. Off for a pint in the Sun now...

Thanks BotB! I am always torn between my desire to see severe weather for myself and common sense. :)

I have actually thought about going to tornado alley in the right season. Maybe we should organize a severe weather do.

^^^ It's something that I'd love to do, and is on my to-do-list. I wonder if any more here are willing to do it too? :)

I LOVE those hand-drawn diagrams, BotB! Keep them coming!

I saw an EK A380 turning over my house yesterday and it literally cut a cloud in 2 with an arc shaped cut and you could see blue sky where it has just been.
By the time I got my iPhone to take a photo it had merged back into 1 cloud again.

When looking down at the clouds, sometimes you can see criss-crosses in the clouds where planes have "ploughed" through them. They remind me of seismic lines.

This A380, literally hoovered up everything in it's path! :D

I suppose it probably related to Zol's re-blingerisation chamber thingygummy? Sucking up all those silver linings of the clouds...

I would be up for a severe weather DO if it was planned for next Summer?

I can't take any more vacation this year (besides what is already planned) but would be keen to do something like this and would be willing to arrange a visit to NCAR (US National Center for Atmospheric Research) where they also do storm watching if that would be of interest?

A few likely places one could go but might be best to consider flying BA into DEN and then visit NCAR and then head East to Kansas or other states where the weather shows are something else...

Are you both up for that? Other suggestions? Anyone else?

Thanks LTN Phobia ^ appreciate the feedback, hope it helps to explain some of the workings and provides some humour as well! ;)

Would like to have seen that ^

I'm guessing that the cloud formed elsewhere and was just going along minding its own business when this A380 plows through it and causes a change of state...in the sense that the air may have just been on the edge of saturation and when the plane went through it, it would cause it to temporarily warm up and not condense but then after the turbulence and heat was radiated up again the cloud comes back...sounds good in practise but haven't seen it in person...Keep that camera handy...;)

I wished I had my camera with me when landing on Thursday as the air was just on the point of saturation when we came into land at LHR...a slight wing angle change on approach was causing cloud to form instantaneously and then immediately dissipate again...fascinating how little lift is needed in some conditions...

I think we should call any cloud dissipation caused by EK the Zol effect ...all that Bling in the air causing the air to subside...:D

Count me in! ^ I'm most definitely up for it.

Like you it will be next year as well, especially if it coincide with the tornado season, hint hint!

Lesson 8: Weather Fronts (or the transition zones between air masses)
 

A Warm Front:

http://i20.photobucket.com/albums/b2...868800x531.jpg
Image borrowed from Heathrow Tower, who kindly posted this earlier in the thread…showing a great example of a Warm Front coming over the water with thickening cloud layer as it moves from right to left and with some Stratus below it…^

and a great fully matured Cumulonimbus cloud picture that could have been due to a Cold Front:

https://lh6.googleusercontent.com/-f...0/IMG_1214.JPG
…again, borrowed from Prospero from a great bunch of photos published at the beginning of this thread…^

So finally getting back to the long promised topic of weather fronts that are responsible for much of our weather in the UK and indeed around the world.

What is a weather front and why is it important?

Well, as previously mentioned, we have a variety of air masses continuously moving around the globe representing the temperature and moisture content of that area of air…

Of course, as with most things, when you have a border or transition zone between two air masses with different temperatures and moisture contents…they cause a conflict…this is what we mean by a weather front. The front is typically a short transition zone between the two air masses.

There are 4 weather fronts (that I can think of right now anyway);

-Cold Fronts
-Warm Fronts
-Quasi-Stationary Fronts
-Occluded Fronts

We'll deal with the first two for this post.

We define a front by the way the COLD air is moving…so if a cold air mass is moving in to replace a warmer air mass that was previously there…the transition zone and front would be called a Cold Front.

Conversely, if WARM air is moving in to replace cold air…the front is called a warm front.

Now, you may be thinking who cares? :eek: Well, as we have talked about in several posts and pictures, cloud or fog always form if we lift warm moist air upwards, causing it to condense and saturate…making cloud and potentially causing precipitation. So what you say?

The transition zone between the two air masses will cause the warm air to move up over the cold air of those conflicting air masses…and causes cloud and weather which can affect flying operations around the world, not just with our favourite airline ;)

The rate that the warm air is forced upwards is dependant on the type of front we have…if the warm air is climbing up over receding cold air, the warm front will typically have a very gradual slope of 1 / 200 (so for example lifting 1 m vertical per 200 m horizontal)…these fronts are typically very gradual and this is why the associated weather is typically very stable cloud types with associated steady drizzle or rain but not showers or any lightning.

The rate that approaching cold air replaces receding warm air is much more abrupt and the height that this friction of the fast moving cold air over a surface happens is much higher due to the speed and therefore the transition zone has a much steeper slope of 1/50 (or for every 1 m vertical lift of the warm air that the cold air is pushing under the horizontal distance is only 50 m) this causes more dramatic lift and more volatile weather so we get unstable clouds and weather such as Cumulus / Cumulonimbus and the associated rain or snow showers with lightning and hail…but as it is faster moving…we also see it come and go much quicker than a warm front.

A cold front would typically move over a location within an hour for example whereas the warm front could take 6 hours to pass through that same site due to the gradual slope of the approaching warm air…

As we get a low pressure area moving in to any space this brings with it on the leading edge a slower moving (retreating) cold air mass with warm air behind (warm front) then we get a fast moving cold front passing through (so cold air coming in to replace the outgoing temporary warm air mass between the two fronts)

http://farm9.staticflickr.com/8153/7...f782c4e3_z.jpg
Air Masses around a Low Pressure System by BA_pics, on Flickr

The strength of these warm and cold fronts depends on the air masses that they are separating. For example if you have cold dry Arctic air replacing only slightly warmer and slightly more humid air then the associated weather between the two air masses will be fairly low key (so maybe some light snow showers at the most and some cloud)…whereas if you have very hot, very humid air being replaced by considerably colder air in the mid latitudes you can get some quite severe thunderstorms and flooding over a short sharp period of time.

The more gentle slope and upward forcing of the warm air in a warm front means that the cloud types are (in order of them appearing over a location…always assuming movement from left to right)

Visual diagram of a Warm Front:

http://farm9.staticflickr.com/8290/7...96f13bff_b.jpg
Warm Front diagram by BA_pics, on Flickr

CI = Cirrus
CS = Cirrostratus (Sunshine loses intensity but still visible through the cloud)
AS = Altostratus (can't see the Sun any longer but typically no precipitation yet)
NS or very thick AS = Nimbostratus or thick Altostratus causing light to moderate drizzle or rain that can last for a few hours or days…
And finally as the front passes through the rain is usually moderate and there is some ST = Stratus that forms below the NS or AS that is passing overhead.

Afterwards…the weather may clear up or remain cloudy in the warmer air.

Wiki page for Warm Front:

http://en.wikipedia.org/wiki/Warm_front

For the quicker moving and steeper sloped cold front the cloud types are convective in nature and therefore you would see in order of appearance:

Visual diagram of a Cold Front:

http://farm9.staticflickr.com/8023/7...b849a119_b.jpg
Cold Front diagram by BA_pics, on Flickr

CI = Cirrus from the tops of the CB (Cumulonimbus) cloud that is coming…
CS = Cirrostratus from the thickening of the Anvil top from the approaching CB cloud if it extends to the tropopause where the Jet Stream will be 'shearing' the tops of the CB cloud off and causing the CS and CI cloud to extend up to several hundred miles in front of the approaching cold front!

Then you get the TCU or CB clouds coming and the associated very sharp rain or snow showers and possibly some lightning and hail…

After the cold front passes, the cold air is generally 'cleaner' so has less cloud due to the lower amount of cloud nuclei for the precipitation or moisture to form around and lower concentration of pollution…but you may still see some CU = Cumulus clouds that develop from what is known as daytime heating…

Wiki page for Cold Front:

http://en.wikipedia.org/wiki/Cold_front

Apropos:

Warm air masses tend to keep lots of pollution and trap particles that moisture for cloud or precipitation can form around, so usually the conditions where you see haze or pollution…Cold air masses tend to be like opening the windows in a house to air the place out…it brings in nice clean but cooler air in that tends not to have the same visibility reductions.

Due to our location in the UK…we get quite frequent frontal passages from the storm tracks that systems take across the Atlantic on their way around the globe so we get frequent changes but don't really suffer from poor visibility or pollution and any associated heath or flying problems like you would see in Greece for example or Beijing. (due in part to the warmer air masses they get and the availability of moisture there as well).

There are some very nice better quality graphics for the weather/temperatures/winds associated with fronts at this location:

Warm Fronts:

http://apollo.lsc.vsc.edu/classes/me.../wf_xsect.html

Cold Fronts:

http://apollo.lsc.vsc.edu/classes/me.../cf_xsect.html

…coming later to a thread near you…Occluded weather fronts and quasi-stationary fronts…

Hope this is also of use and interest.:)

It looked to me like it was quite a thin layer of fairly dense cloud which was just at the exact height of the plane when it passed through.

The 2 1/2's seemed to attract each other which I thought might be due to them having their own gravity and attracting each other that way.

Well no clouds in the sky today, but did spot a few planes above South kensington, one just before wheels down, the other with the moon just after wheels down:

http://farm9.staticflickr.com/8154/7...cd126ced_b.jpg
BA-airbus-before-wheels-down by itsnotmeyouknow1, on Flickr

http://farm9.staticflickr.com/8021/7...d8e26f6b_b.jpg
BA-airbus-and-the-moon by itsnotmeyouknow1, on Flickr

Vain attempts to document the Zol Effect, aka messing around with Google image searches :)

I particularly like the last one !

http://farm9.staticflickr.com/8150/7...0dbe6c0dcf.jpg

http://t2.gstatic.com/images?q=tbn:A...e3aDaOFNXpIBQw

http://farm5.staticflickr.com/4093/4...951f69f491.jpg

http://farm3.staticflickr.com/2143/2...178e23be3c.jpg

Nice pics itsmeitisss and dunk ^

The last few days here (at least Southern England) were indeed extremely cloud free so good to see some nice plane pics in this clear weather as well :)

The third picture of the cloud instantaneously forming from the extra lift of the wing surface causing the air to saturate is a good example of an artificially induced lifting condensation level:

http://en.wikipedia.org/wiki/Lifted_condensation_level

Thanks to both of you for posting them. ^

Not quite cloud free. This high pressure set up a really clear inversion layer at the end of the isle of wight and running out to the nab yesterday evening. Unfortunately I didn't have my camera with me :(

I'll be up for that too I guess... Also next year.

Meanwhile in France...

https://fbcdn-sphotos-a.akamaihd.net...43839377_n.jpg

Wanted to come back to these pictures...

First one: a great picture of wing tip vortices...I don't think Zol would want to produce those! (even for other sections of FT forums ;))

http://en.wikipedia.org/wiki/Wingtip_vortices

This is a great visualisation of why we have stack distances and times on airports...especially with the new A380 I believe the stack time is longer afterwards to ensure that no planes gets caught in one from the previously landed A380 or other aircraft...

The main problem as I understand it is that we do not have a good way to know if the wake turbulence (as it is also known as) will dissipate quickly or if it will 'move' vertically so as not to be a problem...the worry being that the turbulence continues, more or less, in the same path the following plane is taking due to the turbulence being trapped in a 'layer' from temperature variations such as you get with sonar or radar sometimes...maybe someone else better informed can comment further or correct my points here like Heathrow Tower? :)

The cake is great ^ I like the Contrails that are being formed behind the engines! ^:) (A true cake for a flying meteorologist...just need to get a BA logo on the plane and I would be set!)

Oops...You sure that wasn't 'drinking fog' you were seeing? :D

Anyway, I stand corrected...was it some Cumulus, Stratocumulus or something else you saw out of curiosity?

Excellent. I'll start to do some research and post a separate thread regarding the Extreme Weather DO shortly...^

Nice picture of Cirrus there henkybaby ^, I might be imagining it but looks like they were created from Condensation trails left by aircraft? (from the linear tracks and spacing suggesting it is dispersing in a fairly short time as each jet passes by as the air moves across your horizon...

Now for bonus points...is that Cirrus caused by an A380 Contrail or another Airbus Contrail? :D

Thanks for the posts everyone. Keep the pictures coming!

It is aircraft central above my house. Sometime you can see as much as 15 aircraft at the same time creating a chessboard. They fly at high altitude mostly.

Thoughts on StormChasing FT DO...
 

Okay, so have looked at some climate maps and seasonal info and it would appear that April in Oklahoma City area is quite good for storm watching...

I was thinking that we could arrange to meet in DEN (a good BA hub), visit the NCAR site where I hope I can get some friends working there to give us a tour the the public doesn't get (as long as there are not a hundred of us!) and then rent some vehicles to drive out East towards Kansas then down South to Oklahoma City (where we could visit the National Weather Centre and severe storm labs which are open to the public...)

http://www.nwc.ou.edu/tourdetails.php

About 700 miles from DEN to OKC by car...so a long day or reasonable two days if split up while trying to catch a good storm brewing en route...

Oklahoma City gets a hell of a lot of Tornado's each year starting in March and running through to August...late April/ beginning May seems to be the real peak...with 50 Tornado's last year in April...

What do you think about this idea? I think a few days end of April would be best but happy to hear what would be best for anyone interested before posting a new thread on it...

Obviously, not looking to do anything stupid but would be interested in seeing some good storms and just within sighting distance of any big super cells...

AA flies to OKC, BA to DEN, enough hotels in DEN, Kansas and OKC to satisfy most FT'ers for points...

Thanks.^

I think it sounds great, but unfortunately I don't think I'll be allowed to come and play :(

Edit: I just asked and her exact words were "eeeer, but you could die and not come back!" :eek:

I'm interested, and can commit if a date is posted early enough.

Only concern I'd have about driving around looking for storms in the Midwest in a rental vehicle is... hailstones!

I can do this trip, and I can then pop over to see a friend in rural Florida after this "Do".


And from somewhere in rural Queensland, not too far from Mackay:


https://lh3.googleusercontent.com/-Y...3/IMAG0806.jpg

I know that you will read this cloudman, and you have only 30 minutes to answer me before I make up my mind.

1st, you'll be very very proud of me, only and yes only 3 suitcases for a 2 months trip, not bad an improvement. (ok summer clothes, lighter and not bulky ;) :p)

Now the question, one bag is way too packed, should I lighten the load and get another medium sized bag? So it would total of 4 bags? Or should I just stay the way it is? What if I buy something at my destination?

Hope I answer in the time allotted! (see it is longer than 30 minutes but maybe you still have a chance to change...)

Good show, but do take 4 bags to spread the load better and allow for extras coming back...we'll let you off, given you are going for 2 months...have a good trip and take a picture of the clouds! :)

Well I managed with 3 bags, though one is pretty heavy. Oh well.


Am not sure if I can take a picture, I am heading east, so going into the night. I think...But I will try.

I'd be a possible for the trip BotB ^

Great idea and something I'd like to see (from a safe distance of course :D)

Back to Clouds and apparently if there is no actual rain theres going to be fake clouds hung over the stadium with Artificial rain tonight at the Olympic opening ceremony :confused:

Personally I think there may be just a few blokes standing on the roof with hoses :p:D

Pete

Cheers ^, I'll post a thread this weekend on the subject and see what kind of interest we get.

As to tonight: :eek: One hopes that if it is a bunch of blokes, that they will use hoses...:eek::eek::D

Do we really have to stay at a safe distance? :cool:

Well, how about we rent one vehicle from 'rent a wreck' to ride 'shotgun' position allowing those thrill seekers (henkybaby/eightblack...) to get their kicks? :eek:;)

http://farm9.staticflickr.com/8024/7...2b439c7e_z.jpg
li-tornado-damage-car-620-0 by BA_pics, on Flickr

(Picture Copyright: Sue Ogrock/Associated Press)

:D ... and yes, this was taken in Oklahoma....

Preferably on one of these Stormchasing vehicles :p

http://jalopnik.com/assets/resources...orm-Chaser.jpg

Wait a second, there is a cloud meet up and I wasn't informed? :mad: :mad: :mad:.

Just because I packed 3 bags I am banned????? Promise will do only one, if I am allowed to attend. Promise.:p

Well, there is that and there is seeing the storm front from a safe distance away. There must be some middle ground where you can feel the force of mother nature without being launched into space.