The BA Cloud!
 

As there appears to be some interest in the weather and clouds on the BA forum I thought I would start a dedicated thread (with some excellent ideas from as yet undisclosed sources, they know who they are ^) to this aspect of travelling with BA...

Here goes;

This is the BA cloud gallery thread - please post photos of quizzical/interesting cloud formations from your BA point of departure/en route/destination such as from the seat of your BA flight in this thread, together with Flight no, time and location. It is hoped that this will promote discussion and through this we can all gain greater knowledge of the cloud characteristics over our home towns or while travelling to places with BA.

To ensure we keep this relevant to BA...please include a recognisable feature - city, royal blue engine nacelle, or some other distinguishable UK/BA item.

In addition and interspersed with good measure, we can post information on;

-Why the UK (and specifically airports BA use) receives the weather it does and how could this affect your flights or any delays in travelling when we get specific types of weather (this can include destination weather for BA flights as well if desired)

-Post detailed METAR or TAF (and any other relevant weather) information during periods of weather delays or interruption at an airport BA use in the hope it helps those travelling in their plans

-Provide some background on why we have weather at all instead of clear blue skies all the time and how this could affect your BA plans for vacations (thinking Hurricane, Tornado, Monsoon, etc... locations and seasons here)

-Provide a nice diversion for people flying BA while in one of the lounges or sitting in an airport by having some nice pictures to look at!

-post links to relevant sources for more information or where to go if you really get the 'weather' bug!

-have some fun ;)

Of course, any other BA related weather or cloud questions can also be included…just post and we'll see where this goes….

Hope this thread is of interest and gets everyone thinking and talking about the weather on our favourite airline ^

So, look up or out your seat window instead of looking down...and take lots of pictures ^

...first post with clouds or covering one of the above topics coming soon to a screen near you….^ ;)

No clouds where I am.... Just full grey skies. Guess those are clouds.

20 May 2012: BA0233 LHR-DME
 

I recently found myself cloudstruck by these tower formations

https://lh3.googleusercontent.com/-V...0/IMG_1109.JPG
20.05.12 BA0233 East of Moscow

https://lh6.googleusercontent.com/-l...0/IMG_1110.JPG
20.05.12 BA0233 East of Moscow

23 May 2012: BA0232 DME-LHR
 

https://lh3.googleusercontent.com/--...0/IMG_1213.JPG
23.05.12 BA0232 Poland

https://lh6.googleusercontent.com/-f...0/IMG_1214.JPG
23.05.12 BA0232 German Coast

23 May 2012: BA1462 LHR-EDI
 

https://lh4.googleusercontent.com/-n...0/IMG_1232.JPG
23.05.12 BA1462 Lancashire

https://lh4.googleusercontent.com/-x...0/IMG_1226.JPG
23.05.12 BA1462 Lancashire

:D

That would be Stratus clouds then Yahillwe, coming soon...a pictorial guide to the different cloud types!

Excellent start to the thread Prospero ^^ Thanks!

In future, I won't comment on every picture people post but where there is something that hasn't been noted before or where there is something that is not obvious I'll hope comments will enhance the viewing!

In these photos we have really good examples of towering Cumulus...(in METAR and TAF they are abbreviated to TCU)...while we have had pictures of these before...here the reason they have formed is more important...We still need the isolated pockets of moisture and vertical motion from some lower level of convection....however, what is causing that convection is new...previously the TCU in pictures was from mid latitudes along the Equator...in these photos the location is the Russian landscape...which effectively acts as a big frying pan in hot Summer like conditions such as this week...(you can also get this over the Prairies of Canada or the US States East of the Rockies)...The Sun bakes down on the dark coloured soil and due to the warm temperatures of the late Spring acts as a hob for any air above this surface...creating the convective air cycles we need to develop this Cumulus to great vertical heights as we see here...the isolated pockets are where there is more moisture, likely from local sources of water such as rivers or lakes below...

More on landscape and moisture in the different types of air masses coming soon!

Great pics...^

A fantastic example of the striated 'anvil' formation of a mature Cumulonimbus (CB) cloud which probably is 35,000 feet thick vertically from base to that flat top...The top of the cloud is flat and 'sheared' due to the jet stream coming along on top of this cloud and the change in speed simply 'shear' the cloud cauliflower tops off causing the anvil shape with a bit of time. This cloud is likely 25 miles or more wide at the base and would be absolutely chucking it down with heavy showery rain (+RASH) and possibly lightning as well. The height that a CB can 'grow' to depends on where the cloud is formed and what season it happens in...in Summer and over locations like the US/Canada/Russia you can get tops at 65,000 feet, whereas in Winter and over Europe the tops are much more modest at around 30,000 feet. This is generally a reflection of the height of the Tropopause at that location and season.

A really good picture of AC floccus from above...below this would look very flat and just like cotton balls scattered in 2D on a blue background...but here you can see the 3 dimensional aspect of the cloud which again shows the instability at that height and the convective cycles where the upward vertical motion is where the white cloud bits are and the warmer air which can hold more moisture is subsiding where there is no cloud. (think of mini vertical circles with the direction being upward where there is cloud and downward where there is no cloud...this is why you get a 'patchwork' field of the clouds...the downward flows can be thought of as punching downward holes in the cloud deck...:D

One for the cloud atlas I would like to display on here, if you are in agreement Prospero to help ID different clouds, types and heights?;)

Oh I thought you were talking about the BA Cloud Kinetic Sculpture at T5 :D Ooh and I need to send you a PM. ;)

BotB YG cloud badge related PM. ;)

I've taken a couple of photos ... I'll post when I get back home to an iMac instead of an iPod. ;)

Great descriptions BotB

I definitely have too many. I will try to spread the love over a couple of days...

Easter Island
http://pic40.picturetrail.com/VOL359.../348940173.jpg

Approaching SYD from LAX
http://pic40.picturetrail.com/VOL359.../349755517.jpg

Somewhere in New Zealand
http://pic40.picturetrail.com/VOL359.../350178809.jpg

Between SYD and CHC (2x)
http://pic40.picturetrail.com/VOL359.../350178732.jpg

http://pic40.picturetrail.com/VOL359.../350178739.jpg

New option for Cloud Club design
 

Jimmy76 has been busy...what do you think?

http://farm8.staticflickr.com/7072/7...aa655b0311.jpg
cloudbadge2100 by Jimmy76, on Flickr

Great colours here and a real feeling of being about mid level of the TCU clouds which are scattered around...not exactly sure why the very isolated small Cumulus clouds can develop into really skinny TCU here with the Cirrus (CI) cloud above but a nice picture and again a great perspective. ^

I just really like this one...a great perspective henkybaby ^ , you seem to have a way of portraying being on the plane as it is climbing or descending through the cloud layers...brilliant.

I particularly like the very strong deep blues at the top and the varying shades of white and grey of the clouds...looks like some fairly stable Altocumulus below and a layer of Cirrostratus above.

My favourite cloud, and on-topic for this board too!

http://www.youtube.com/watch?v=42hgPLL8IrA

A provocative first class...
 

Why do we have weather? Why is it not 25 degrees C and sunny blue skies everywhere? How is this related to BA and my flights?

I'll try to keep things very simple, interesting and fairly short in each of these...hope they are of interest and do not upset too many if I simplify the physics involved!

Effectively it all comes down to temperature.

http://farm8.staticflickr.com/7092/7...54ac028458.jpg
thermometer by BA_pics, on Flickr

Yes, temperature. If we had a 'closed' system (there was no Sunshine heating us unequally from above and the world was flat and heated equally throughout the air with no change or difference in absorption we would indeed have no weather! (don't worry, not going to happen!)

Because we get the Sun heating the atmosphere and the Earth's surface unequally around the world...this causes a difference in temperature both vertically and horizontally...between the air at the surface and the air at the higher levels in our atmosphere...as well as the temperature of the water in the ocean and the soil on land...and in the process of trying to balance out the temperature over both horizontal and vertical distance we get wind.

We would have no wind if the temperature was uniform in our atmosphere. However, luckily for us, there is a strong difference in temperature both in the vertical and horizontal scales...the stronger the difference in temperature, the stronger the wind from the need to try to balance out this difference (A jet stream is nothing more than an extreme difference in temperature between two air masses.)

Jet Stream description on Wikipedia

Once we have some temperature gradient and therefore some wind...we have weather...as once you move a 'cube' of air from one place to another, vertically or horizontally, it changes accordingly to the conditions...it may either contract or expand due to temperature and the fixed amount of moisture in that 'cube' will reflect the change in temperature of that cube, creating clouds, precipitation or dissipating cloud at the other extreme...

The good news is that without these temperature differences we would have a much harder time trying to get from one place to another...as we would have no wind to flow over an airplane wing and no jet streams to help speed us on our way across larger distances making fuel consumption and times much higher (forgetting the fact that life may not exist in a closed system...however, I will simply ignore that fact for this discussion!)

So the next time it is raining or cloudy in the UK or your BA flight is a bit bumpy...remember that this is actually very important and good at the end of the day as otherwise BA would not be flying you to your destination!

On the next episode of weather....

Air Masses...they are massive but there are not masses of them :)

Cambodia

http://pic40.picturetrail.com/VOL359.../364745837.jpg

http://pic40.picturetrail.com/VOL359.../364745845.jpg

South China Sea

http://pic40.picturetrail.com/VOL359.../366641920.jpg

http://farm5.staticflickr.com/4114/4...f95bde00_m.jpg
Dawn finals into Hong Kong by steve_w, on Flickr

^^^

Nice one.

I thought they were supposed to be BA related?

Ah, missed that. Well, in most cases BA got me to the region. Will that suffice? :cool:


Taken from Comair (JNB-CPT)

http://pic40.picturetrail.com/VOL359.../394607820.jpg

Oh well then I'll start looking out my selection of cloud pictures from the top of Ben Dorain.

Funnt that, I was looking at some old photos for clouds with different formations too!. Some cracking pics so far. Well done BotB for starting this ^

Part of my job is looking at clouds (from above, with satellites) and so this thread seems pretty interesting. Keep it up, guys!^

This one reminds me of an Edvard Munch picture.


Great explanation, BotB. I've always wondered why the weather doesn't just reach an equilibrium - now I know why. :cool:

I think I have learnt something about myself. I went "ohhh, a rude cloud"! :eek:

Okay, these two photos show the difference between a text book Cumulus cloud (from henkybaby ^) with very sharp, well defined edges to the cloud (see how the cauliflower bumps have very good contrast to the air and you feel you 'know' exactly where the cloud starts and ends) to the very different Cumulus fractus sub species in steve_w's picture...the edges of the clouds in the foreground are much less precise around the edges and seem to gradually 'fade' into the air (also the colour tends to be a gradient from the brilliant white through a number of shades of grey to almost transparent)...this 'blurry' edging tends to be what is called either Stratus cloud or a fractus sub species of a cloud...depending on how it was formed...Here (still talking about steve_w's clouds in the foreground) it is Cumulus fractus as the type of cloud in the air is a convective cloud formed from the heating of the atmosphere and hot air rising to cool off and then subsiding after it becomes quite cool and sinks to warm up again...The fractus clouds here are different to the background well defined Cumulus or TCU because there is less heating here in the foreground as the Sun is behind cloud or is not heating this air as much as the air in the background and these CU fractus are effectively only small isolated pockets where there is still some convection and a small amount of remaining super saturation that forms the fractions of cloud at that height...effectively trying to balance out the temperature and moisture in the air parcels here...in the background the much more well developed TCU are still being heated from the Sun on top as well as the rising warm air from below and probably some sea breezes from the land to water exchange as well...These TCU will develop even further and quicker in such warm, moist locations when the Sun is setting or just rising as the atmosphere is effectively experiencing a very abrupt and strong 'flipping' of the hot / cold air...during the day the lower surfaces are warmer and try to rise and the upper heights are colder and try to sink...but when the Sun is strong or it is Summer (in the Northern Hemisphere at least) then when the Sun goes down or is just rising the air at the upper heights is actually heated more than the lower regions (in morning) or the air at height is cooling far quicker than it was previously and therefore sinks quicker causing the convection to seem to be on 'boil' setting for about 20 - 30 minutes until some equilibrium is reached and things balance out again...for this reason we get more showers of rain and cloud development around mid morning and just after the Sun is setting in the evening! It is also why some clouds that previously only gave rain showers in the afternoon or early morning then suddenly give lightning and thunder as they get that little bit extra 'kick' from the atmosphere to become a full CB cloud and have the energy to produce the extra 'effects'...

Sorry, get a bit excited about the power and forces at action from mother nature in these pics and tend to go off on one...hope it is still of interest and makes sense? Let me know if something is not clear and I'll try to do better next time...promise!

Excellent Pictures everyone, thanks for contributing...keep them coming please! ^^^

It is desired that the pictures are indeed taken from BA aircraft (hence the blue engine cowls showing in Prospero's pics ^ ) or a UK location or at least have some tie to BA or UK city, etc...I am certain the MOD's will forgive the odd excursion into foreign parts or transgression...but to keep this thread here we do need to keep this BA relevant please where possible!^

LHR-HKG

http://pic40.picturetrail.com/VOL359.../364486977.jpg

http://pic40.picturetrail.com/VOL359.../364486992.jpg

http://pic40.picturetrail.com/VOL359.../364486966.jpg

AMS-JFK on OpenSkies

http://pic40.picturetrail.com/VOL359.../368605673.jpg

Somewhere in Kenya

http://pic40.picturetrail.com/VOL359.../373407231.jpg

ActuallyLTN Phobia, you raise (no pun intended :)) a very good point...

People ask 'why is it so hard to forecast the weather?'...

https://lh3.googleusercontent.com/-V...0/IMG_1109.JPG
20.05.12 BA0233 East of Moscow from Prospero

This picture illustrates the problem perfectly....why in a fairly small patch of Cumulus cloud is there all of a sudden this fantastic and aggressive growth occurring? What perfect conditions exist in that one place at this moment in time to allow such development of the cloud here but no where else?...The answer is we don't know exactly but are trying to find out...So how do we do this...

We find special cases like this particular situation and then try to get as much data as possible about what the conditions were like...This equates to collecting (where possible) up to 100 variables such as temperature at the surface, at 10m, at 100m, etc..., humidity at the same levels, pressure, wind, cloud cover, solar heating at several bandwidths (short, long, total, direct, indirect), aerosol particle counts, gas constituents, etc...then we look at the geography at this spot and try to then put the specific lifting, heating, cooling convergence, divergence, etc....actions into the computer given this landscape and then run one simulation against all other variations (adjusting the weighing of each parameter against the others) to find what scenario creates this development that nature has made...then we try to repeat this on other similar areas of landscape and heating, season, moisture, etc...to see if they do repeat predictably...if they do we create what is known as a 'local model' that we apply to the super computer when it is running the various scenarios for the weather in the UK...taking into account (where possible and known) all of the 100 variables and all of the local geographic variations and the effects these variations will have on the weather to become modified....You can imagine the amount of 'runs' of the simulations that are needed to figure out which scenarios are most likely and seem to repeat (giving a greater probability)...

So we are effectively trying to understand the very small scale, small scale, mid size scale and large scale effects and how they all interact together with the various 100 or so 'modifiers' such as temperature at a specific height, solar radiation at a specific location at a specific season or day...to see what the best 'gamble' is...due to percentages as we don't yet know all of the interactions and outcomes for each specific scenario...but we are learning them more and more quickly and able to forecast them better with more and more computing power...

To give you an idea...we are now able to run 'local scale' grids for the computer models down to roughly 1.5 Km cubed...Given the diameter of the Earth that is staggering really...of course we don't run the whole Earth model at this fine scale all at once...but we do for the UK for example and that as often as possible to keep up with the current conditions that we have measured and try to ensure we are weighing the correct parameters with the correct scores...

It all boggles the mind really...

So, very isolated, extreme events such as this one TCU cloud in an otherwise very normal CU cloud deck does make for some interesting science ^ :D

However, you are correct...it would indeed be quite 'rude' to fly through that cloud at that particular time as the updraft would be quite decent I think...again the popcorn analogy works well here...just on a bigger scale...:)

Sorry, gone off on another one! :eek: Right off to dreamland then...

Well any of mine will be BA related....Buenos Aires. :p

Now that you mention it I can see that too...^

Thanks, you have made me realise that I missed an important point above in my 'temperature' notes though...so will try to correct that here:

There is a 'balance' globally and a finite amount of energy as well as water, etc...we do not gain or lose anything forever (otherwise we would run out of water or energy!)...however, because of the unequal external influence of the Sun and the heating up of the air and surface (and therefore uptake of water from our oceans and production of cloud, etc...we get the balance of the energy by having it rain to give back the same amount of water to the oceans...or have cold air subsiding elsewhere to ensure that the energy is balanced...it is really a 'closed' system with nothing lost or gained on a global scale...but the system does not achieve a final state of balance because there is always some external influence like the warming or cooling going on (temperature change) which then causes the rest of the global weather to balance this out in terms of energy, water, etc...and this is why we never get a final completely rested, equal and balanced temperature state throughout our atmosphere and hence why there is always weather...

Hope this explains things a bit better (or more precisely)...;)

Great pics henkybaby ^

I love that although there are only two cloud levels in this photos (some Cumulus at the lower level with the 'embedded' TCU in the background and the upper Cirrostratus (CS))...it appears there are many more due to the light filtering through the CS cloud and the background shades of blue in the middle of the picture...was that from rain back there or was the Sun just rising or setting when you took this picture?

I find this picture reminds me of a science fiction scene! ^ Beautiful.

AMS-JFK on OpenSkies

A perfect example of the sub species 'undulates' in a cloud. Here in what looks like some quite thin Altostratus ^

http://en.wikipedia.org/wiki/Altostr...ndulatus_cloud

Ah...was wondering when we would get a nice picture showing 'Virga'...^

I am going to let everyone Google that one to find out what Virga is....I'm such a tease aren't I? :D

I can't speak for everyone, but I find your explanations interesting BotB. My experience is restricted to the very practical use of visual local observation or drawing synoptic charts. So to hear the proper explanation, rather than the rules of thumb I know, is very useful.

A trip in the Clouds on BA and AY (codeshare)
 

BA/AY codeshares LHR -HEL -LHR 22 May out, 25 May back…with some nice sunset pictures first...

http://farm8.staticflickr.com/7244/7...d4466510_z.jpg
High AC at HEL by BA_pics, on Flickr

Had some brilliant Sunny weather in HEL this week and in the land of the midnight Sun (not quite there yet as the sunset pictures were taken at 23:30ish) I couldn't resist some pictures of this good weather. Above, some high (I am guessing around 14,000 feet) Altocumulus wisps with a really nice sunset in the background.

A close up:

http://farm8.staticflickr.com/7085/7...9e095891_z.jpg
AC Castellanus HEL by BA_pics, on Flickr

Showing some ACC (that's Altocumulus Castellanus) developing as the Sun goes down…not enough moisture to develop further but still interesting.

Then the night before heading back to the UK…we had some nice friendly CI (Cirrus) come South…Also some AC in the background (bottom right darker clouds)…sorry for the UFO like light reflection from the room lighting in the hotel. :(

http://farm9.staticflickr.com/8151/7...317f6704_z.jpg
HEL 24 May near midnight by BA_pics, on Flickr

Now….on to the trip back by the clouds I encountered…

http://farm9.staticflickr.com/8154/7...13070a58_z.jpg
HEL Finnair Lounge Cloud TV by BA_pics, on Flickr

My colleague and I had a few hours before the flight so we settled in to the window seats of the Finnair Lounge at HEL and watched Cloud TV…better than any daytime soap I can assure you ;)

As many of these things do…everything started out innocent enough….a nice blue sky with some Altocumulus and a smattering of Cumulus fractus…

http://farm8.staticflickr.com/7099/7...00e78920_z.jpg
HEL CU Fractus by BA_pics, on Flickr

However, to my pleasure…The sky was constantly changing….It started to change from some AC undulates to some AC floccus to Altostratus with some Lenticular clouds forming! All this indicating that the mid level atmosphere was becoming more stable but the winds were developing enormously at that level as well…due to some convergence I am guessing but will have to look into the mountain and topography around Southern Finland more to be sure…

So we went from this:

http://farm8.staticflickr.com/7239/7...a3ffbf60_z.jpg
HEL AC Undulates by BA_pics, on Flickr

To this:

http://farm9.staticflickr.com/8149/7...905ecaf4_z.jpg
HEL AC Floccus detail2 by BA_pics, on Flickr

To this (much more surreal and exciting!):

http://farm8.staticflickr.com/7096/7...f03322f5_z.jpg
AC Lenticularis by BA_pics, on Flickr

http://farm8.staticflickr.com/7243/7...2e8442b6_z.jpg
HEL AC Lenticularis by BA_pics, on Flickr

At which time, it was naturally time to board our flight to experience that turbulence first hand…

Unfortunately, I was seated at what looked like the dirtiest window in the fleet and on the wrong side of the aircraft for pictures when heading back to LHR…however, I hope they still provide some detail and are of interest…

Didn't take any pictures for the first few minutes but as we were ascending and heading South we were coming up to the AC bases at around 7000 feet (according to the moving map):

http://farm8.staticflickr.com/7090/7...901e8442_z.jpg
HEL LHR ascending to AC deck bases 070 by BA_pics, on Flickr

I did try to get some good pictures when we were just around the tops of the AC but the Sun was shining through the CS/CI cloud higher up by then and foiled this quite a bit…

http://farm8.staticflickr.com/7096/7...6379703f_z.jpg
HEL LHR AC tops ascending through dirty window by BA_pics, on Flickr

http://farm8.staticflickr.com/7078/7...6704a128_z.jpg
HEL LHR AC deck by BA_pics, on Flickr

http://farm8.staticflickr.com/7220/7...3c37de99_z.jpg
HEL LHR AC Floccus2 by BA_pics, on Flickr

Then as we got up to cruising altitude, the Sun made most pictures unusable…but I will post one or two anyway…

http://farm9.staticflickr.com/8154/7...052b2dda_z.jpg
HEL LHR CI and AC through dirty window by BA_pics, on Flickr

http://farm8.staticflickr.com/7079/7...8fbc239e_z.jpg
HEL LHR CS and CI by BA_pics, on Flickr

http://farm8.staticflickr.com/7245/7...ce98d55c_z.jpg
HEL LHR CI by BA_pics, on Flickr

So we went from the high level AC and CS to no AC at all then to the CS thinning out to become CI only and then nearly nothing at all…

I wonder if this is the first cloud report on FT? (I didn't take one picture of the inside of the plane or food, etc.. and the people around me definitely thought I was nuts snapping pics and oohing and ahhhh'ing while cursing the Sun….:D

Hope these are interesting and if there are any questions please do ask! ^

A while back on 28th April doing the MEL-PER run, at cruise level over the Great Australian Bight, we were in still very thick hazy clouds. There wasn't much of a break in between clouds as we descended into PER, the lowest layer was clearly nimbostratus with the associated rain.

But what sort of clouds would it be at quite high altitude that is quite thick and uniform? Is it possible to have a nimbostratus at such high altitudes?

It is vaguely BA related because I redeemed Avios on this flight. ;)

Lesson 2: Clouds
 

Okay, I lied...I was going to talk about air masses but...as the question came up first...here is the revised lesson 2! Again, some things may be simplified to keep this to a chapter of war and peace!

Getting to grips with the various clouds is quite easy really…once you know the rules ;)

We name the cloud by the height the base of that cloud starts at. We only really have two cloud types and we put 'Alto' in front if it is mid level based or 'Cirro' if it is high level based cloud.

So that gives us:

Cloud types: Cumulus and Stratus

or Altostratus, Cirrostratus and Altocumulus, Cirrocumulus.

Some special names for variations on these clouds are:

Fog (which is Stratus cloud that is touching the ground) and Cirrus (not quite Cirrostratus nor Cirrocumulus but we'll leave that for another day)…

So what is the difference between Cumulus and Stratus? Cumulus is formed from convection and turbulence type movement and generally is more isolated (each individual cloud is typically no bigger than 25 miles for example (that would be the biggest, a Cumulonimbus cloud) and many are much smaller at only a few hundred meters wide or a Mile…Cumulus clouds have the well known 'cauliflower' type bumps on the top and have well defined cloud edges with grey or darker bottoms. The Cumulus clouds produce intermittent showery rainfall and do not rain for hours on end…(there has to be breaks between and showers from Cumulus tend to last 15 -40 minutes from one cloud).

http://upload.wikimedia.org/wikipedi...ldenMedows.jpg

Stratus is generally formed by a large amount of warm moist air along a warm front or some other occasion that pushes a large 'sheet' of warm air aloft….but is not formed by convection or daytime heating of the Earth. You do not tend to get an isolated Stratus cloud, rather the Stratus tends to be several 10's if not 100's of Miles long (and can cover the whole sky). Stratus clouds are usually opaque or at their thinnest are at least transparent. These clouds are associated with stable atmospheric conditions and have continuous rain rather than showers.

http://upload.wikimedia.org/wikipedi...-Uniformis.jpg

so starting from the bottom (ground level) we have the following stable type clouds:

Fog
Stratus
Nimbostratus
Altostratus
Cirrostratus

And the following convective type clouds, again from the ground up:

Cumulus
Cumulonimbus
Altocumulus
Cirrocumulus

Wait just a minute…what's with these 'Nimbus and Nimbo' clouds I hear you say? ;)

Well, we above stated that we name a cloud for the height that the bases of that cloud start at…

Usually a cloud is a few thousand feet thick and then there is a break in the cloud and if there is anymore moisture at a higher level we name that cloud after the base it would start at…or:

some stratus at say 1000 feet and then clear air and then some Altostratus at say 8000 feet.

But what happens when we have cloud that starts at one height and continues in one continuous layer up to a height n?

We name it after the first base layer..but most clouds don't extend more than say 4-6,000 feet in thickness so we have made two cloud types (one for each type of process)….or Nimbostratus for a very low very thick Stratus cloud that extends several 10's of thousands of feet and Cumulonimbus for a convective cloud that extends from the lower levels up to 65,000 feet at the highest!

EDIT: So starting from the ground and not separating the types of cloud we now have (including abbreviations used in METAR or TAF information):

Fog (FG)
Stratus (ST) / Cumulus (CU) (including Towering Cumulus (TCU))
NimboStratus (NS) / Cumulonimbus (CB)
Altostratus (AS) / Altocumulus (AC) (including Altocumulus Castellanus (ACC) a mid level equivalent to TCU)
Cirrostratus (CS) / Cirrocumulus (CC) / Cirrus (CI)


And how do we know when to start calling a cloud Altostratus instead of Stratus for example?

Internationally we have agreed to use guidelines for the heights that each cloud can be based at:

Well, Fog is easy! Its based on the ground and can extend up several hundred meters.

Stratus and Cumulus can start at 100 feet above ground and we stop calling them that when they have bases above 6,500 feet (above ground level which is used internationally).

Altocumulus and Altostratus are based at heights from 6,000 feet up to 18,000 feet.

Cirrostratus and Cirrocumulus are based at any height above 18,000 feet.

There are some variations to this such as the very dry, hot, plains in North America and Russia…we can see reports there of Cumulus at heights of 8,000 feet for example as the conditions allow it…but this is rare.

Nimbostratus has a special clause that generally suggests you may not call a cloud Nimbostratus unless it:

-has a very black base that is hard to see what height it actually is based at…
-has been raining for several hours or days continuously
-is based below 1000 feet (this varies by country…like currency…with some common values held in some countries!)

Cumulonimbus is different to a Cumulus cloud in that it can produce (which Cumulus cannot):

-lightning
-hail
-if the cloud has an anvil form on top it must be Cumulonimbus
-there is no height limit for CB clouds like Nimbostratus has…typically a Cumulus cloud base will get higher as the day progresses or as the cloud develops…so it could start out at 2,000 feet above ground and later that day be the same clouds but based at 4,000 feet with the rising air temperature.

We also have mentioned Towering Cumulus…this is the name we give to Cumulus when it starts to develop into a narrow but thick finger of Cumulus type cloud…it is also the beginning of any Cumulonimbus cloud…so you have to have Cumulus then Towering Cumulus before you can have Cumulonimbus develop in front of you…obviously any cloud can 'move' into your area but to develop it must follow that development first.

Towering Cumulus cannot have:

-lightning
-anvil form on top

We have sub species of the clouds as well but I will leave that for another time…

So, we have still not talked about Cirrus…what's up?

Cirrus is very thin, hook like wispy cloud at heights above 18,000 feet which are neither Cirrostratus nor Cirrocumulus….and the water content is made up of ice crystals instead of being water or what is known as mixed phase cloud which has both.

You can find out more about each of these types of cloud by looking them up on Wikipedia or the Cloud Appreciation Society! (yes, one exists)

So to finally answer your question Stez …

lf the cloud was based below 6,000 feet and was continuous for several thousand feet or 10's of thousands of feet thick then it was definitely Nimbostratus (yes, that is one thick continuous cloud that can be 60,000 feet thick in some cases!). If the cloud was based at 6,000 feet or higher and extended continuously for several thousand feet then it was Altostratus and if the cloud was 'only' based at a height above 18,000 feet or higher (it could extend from here up to 60,000 feet) then it was Cirrostratus.

Likely Nimbostratus…if you have Nimbostratus it tends to extend for several hundreds of miles and be around for a good while (up to three days!)

And to keep this BA related...some clouds are more likely in the UK such as Stratus types and some Cumulus types...but although we get them...it is quite rare to have a Cumulonimbus in the UK...Equally, we don't tend to get Nimbostratus as we don't get the very strong clashes of air masses that can form this either...so much like our temperatures we tend to be very moderate and in the middle...with a few exceptions and extremes just to keep things honest...

Hope this is still interesting...please do keep giving feedback and let me know if these posts are turning into tedious unwanted noise or if you would like to see a different style, etc... I take criticism well, honest!

^:)

BotB a question....

Related to a flight I was on but can't find the pictures. It was an interesting flight between GRU and EZE. We were flying at around 33,000 feet and weaving our way through horrible looking storm clouds which towered even higher in the air than us. I reckon they must have reached 40,000 feet at least maybe more.

What's the maximum height clouds can reach?

Having just googled "maximum cloud height" (see what you've done, BotB) with a question along HIDDY's lines, one of the results was a paper on maximum likelihood estimation of cloud height. I'd never even have considered that MLE could be applied to clouds. Does your field require that sort of thing?



(Apologies for the economist-esque questions on why there's no equilibrium and now statistical techniques)

A (well worded) question with a few answers ^ What you were flying through were Cumulonimbus clouds without a doubt....

The highest height a 'normal' cloud can reach is the tropopause...which varies with the seasons and location on Earth...but is generally agreed to be around 65,000 feet above ground. (according to ICAO)

The second part to your question could be interpreted as how thick can a single cloud be? The answer would be generally be 63,000 feet thick! :eek: Why? Generally the only cloud that could be that thick is a Cumulonimbus cloud which to achieve this kind of thickness would definitely be based around 2000 feet simply because of the temperatures needed to get the convection to achieve a fully mature thunderstorm and CB. There are many examples of such clouds and I am sure you have had these in your location HIDDY, which would be interesting but also can be very scary and indeed life threatening!

The final answer to your question could be a trick question...although not considered part of our normal 'clouds' these Noctilucent Clouds are generally considered the highest clouds in our atmosphere at 53 miles above the surface!

:D

And if you really want to think outside the box...there is actually a science for 'planetary meteorology' in which 'clouds' are talked about on other planets but they are generally not included when answering your question...

Definitely no apology needed! Discussion and exchange are great ^...who knows what comes out of such discussions unless they are engaged...the equilibrium question is one that is addressed all the time...for example Kolmogorov’s -5/3 power law to close the energy balance...Meteorologists do all sorts of statistical analysis on micrometeorological data...

I personally do not know of the MLE but you have made me curious so I will be checking that out! ^

EDIT: having briefly looked at this, I certainly believe we would use this but can't give you an concrete examples. Thanks for making me aware of this. We do tend to use PDF (Probability Distribution) Function so many others that may be crossover concepts...

It is indeed interesting that quite a few mathematical concepts are defined for one area and then can be applied to something completely different!

Glad to hear I have made you curious and look forward to other questions! ^:)