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Thread: War-time Bombing Weather

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    Default War-time Bombing Weather

    What was the ideal weather for night bombing please. For long I have been thinking that bright moon lit nights were the ideal but now I'm not so sure as these conditions would have highlighted the aircraft at least. I can understand the effects of tail, head and cross winds but do not understand the effects of moon and cloud apart from low cloud but with radar.............

    I am assuming the night and day bombers flew VFR when in cloud and apart from the early war years, would have used radar for target location. Could the resident experts please enlighten me. My simple head is starting to fill with contradictions and needs urgent attention. Thank you
    Norman

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    Norman,
    It is hellishly difficult to give a definitive answer to this one. So many factors were involved with each set of weather conditions.
    In the early years bright moonlight gave good visibility to aid navigation and target identification, but later, moonlit nights brought nightfighters and accurate flak. Dark winter nights meant less chance of visual "fixes" for navigators on deeper penetrations into enemy territory, but did not favour the nightfighter so much since, on both sides, the final moments of an interception relied on the pilot of the fighter gaining visual contact with his victim. Thick cloud had obvious drawbacks for both bomber and fighter
    whilst thin overcast with searchlights playing on its underside would silhouette the bombers to high flying fighters. There then comes problems such as icing, turbulence, headwinds interfering with carefully worked out timings, unexpected crosswinds causing excessive drift off track, condensation levels etc etc.
    During the war, radar was not as reliable or efficient as that of to-day. Allied H2S whilst it helped, was frequently unreliable in function and rarely gave a good clear picture of the ground below except perhaps over large stretches of water (coastlines, rivers, large lakes etc.) Built up areas were often poorly defined, making identification of a town difficult. Over the Ruhr for instance, where one large town was close to or connected to another, H2S was rarely up to the job. Even towards the end of the war when Oboe, H2S and other nav aids had improved markedly, the standard issue Mark One Eyeball was still probably the most reliable means of seeing where you were, the old law of physics that says you cannot see in the dark notwithstanding.
    Other forumites better qualified than me may be able to offer more definitive answers but aircrew I have spoken to on this subject have generally always replied along the lines I have stated above.
    Regards,
    Bill.

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    1) Clear and benign conditiions over Britain during take-off and landing.
    2) No icing, or storm conditions.
    3) No moon.
    4) No snow on ground. Snow on the ground scared the hell out of my dad on the Pforzheim trip as he felt every fighter in Germany could see him from above against the backdrop of snow on the ground. Coincidently the moon was near full, according to historical records.
    http://tycho.usno.navy.mil/vphase.html
    5) Some cloud over the continent for cover against fighters.
    6) Good wind forecasting
    7) Clear over target providing good visibility to bomb aimers and markers.
    8) Low humidty for several days in the target area prior to attack to facilitate fires.

    Put simply weather favourable for survival of aircraft throughout the trip, good visibility during takeoffs and landing, some cloud cover on route to target but allowing for good visibility over target. Low humidity to facilitate fire storms.

    All this presumes good navigation, which was normally routine late in the war, but then you asked about weather so...

    Jim
    Last edited by JDCAVE; 28th January 2009 at 03:58. Reason: Clarity, more information

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    My father was an AG from 1938 on, full moons in our house were always known as a "Bomber's Moon"

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    Norman,

    I think Bill and Jim have provided sensible resumes but I'd like to make a few comments on Jim's list:

    Item 1. It's a bit vague, I think that what is meant is no very low cloud, fog or snow - and then mostly for the return rather than departure. An aircraft could take off in pretty rotten conditions, but putting it back on the ground again was another matter.

    Item 2. Again vague; I think what is meant is severe icing and thunderstorms. The two usually go together, although severe icing can be found in cloud associated with active fronts.

    Item 4. I've never heard of that one before and doubt it came into consideration when planning an operation. The effect would be no different for aircraft flying on top of cloud layers so it's difficult to see why this particular concern.

    Item 7. Not sure what's meant by this. Why 'good wind forecasting' and no similar comment about 'good cloud forecasting'? I suspect what is meant is favourable winds that facilitated a rapid transit across enemy territory with a minimum of navigation problems.

    Item 8. So far as I'm aware that's incorrect. My understanding is that raids which resulted in 'firestorms' (thinking particularly of Hamburg and Dresden) were never planned but developed as a result of unusual circumstances.

    Brian
    Last edited by Lyffe; 28th January 2009 at 12:32.

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    Re item 8 - brain's just clicked into gear, although I don't think the following refers to 'firestorms'. One of the Air Ministry's pre-war War Plans was to burn German forests (on the assumption they could be used to hide supply and ammunition dumps) and cornfields), and to this end small incendiary devices known as 'Razzles' (for the forests) and 'Deckers' (for the crops) were devised (these are mentioned in the 'Bomber Command War Diaries).

    Razzles were small pellets of phoshorus inserted between pieces of celluloid, whilst Deckers were impregnated pieces of cloth. They were transported in water containers for release over the target areas. As they dried out they were supposed to burst into flame and start fires.

    Well, that was the idea. Unfortunately the little blighters had this nasty habit of getting caught in an aircraft's tail after release and more damage appears to have been done to the attackers rather than the targets. Amongst the units involved were 10 and 77 Sqns.

    There were a small number of operations using these devices between July and November 1940, but they were never a scuccess.

    Which brings me to the meteorology. AP1134 (The Second World War 1939-1945; Meteorology) includes the following when describing the work of the Central Forecast Office:

    'Cliquot' forecasts; were supplied to Bomber Command and B. Ops. 1 in connection with a project to set fire to the forests of Germany by means of incendiary weapons. They involved estimates of past weather, including rainfall, and future weather and winds. They were begun in July 1940 and discontinued in October 1941.

    And before anyone says anything - it's true I promise you.

    However, there is no direct reference to humidity.

    Brian
    Last edited by Lyffe; 28th January 2009 at 12:33.

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    Brian: I quite agree that my comments were vague as pertains to meterology, per se. Also, some of the generalities I identied may not have been routinely considered by meterologists and planners. What I have provided is more a summary from the perspective of the aircrew.

    Humidity may not have been taken into account during the planning of bombing operations, but it certainly had a profound effect on the success of certain raids, such as Dresden, Hamburg, and Pforzheim, from what we understand after these events. Many people don't realize that often the driest conditions occur during very cold weather in the winter. I find that my firewood outside (even the well seasoned stuff) is much drier at this time of year than in the fall after a hot summer.

    We have discussed the "rotten" conditions encountered by many crews during takeoff during the March '45 Chemnitz operation so it is a factor. Surely the success of bombing operations should be evaluated in part on whether crews are lost during take-off and landing?

    As pertains to wind finding: It would seem to me that strong and highly variable winds would be problematic for wind finding, ultimatly navigation and "Time-over-Target". Any such errors in this would ultimately cause greater deviation in ToT's, something that crews were evaluated on during the later stages of the war. I have been reviewing 6-Group records for fall-winter'44-winter spring '45 and there is considerable review in the records pertaining to the problems of wind finding and broadcasting winds. The 6-Group records are highly critical of navigators during this period and notices were constantly sent to the squadrons within the group to tighten up on navigation procedures, in particular maintaining on track, turning points and ToT's.

    The issues dad indicated with the snow on the ground may not have been encountered often and I am certain that Command didn't consider the problem, but it certainly frightened Dad. It is different than being spotted against layers of cloud, because you can dive into cloud to hide or adjust height to minimize the chance of being visually identified, but you cannot dive into the snow on the ground and come out alive! Dad indicated that he was jumped twice by single engine fighters. As these aircraft did not have radar or ground controllers to vector them onto aircraft, the conditions that night certainly would have aided in the success of these fighters.

    Jim

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    Jim,
    What you are effectively saying in your last paragraph is that German nightfighter pilots were a canny lot and would take advantage of any prevailing conditions at the time. That they did so with such marked success only illustrates how hazardous an existence our night bomber crews led.
    Bill

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    Quote Originally Posted by Lyffe View Post
    Norman,

    Item 8. So far as I'm aware that's incorrect. My understanding is that raids which resulted in 'firestorms' (thinking particularly of Hamburg and Dresden) were never planned but developed as a result of unusual circumstances.

    Brian
    Wasn't the "fire storm" trialled at Luebeck some months earlier- a port, old buildings and warehouses densly packed? Much like Hamburg, just smaller

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    The Lubeck raid took place shortly after Harris' arrival at HQ Bomber Command and resulted from a directive to focus on the morale of the civilian population. Lubeck was chosen as many of its buildings were of timbered construction and the Air Staff were keen to see the effect of using large quantities of incendiaries. To that extent the raid was a trial, but I suggest it would be wrong to say the intention was to create a firestorm - I believe the term was created after the Hamburg raid. Huge numbers of incendiaries were used in that raid as well, and concentrated on a small area. It was the extremely high temperatures resulting from the initial fire that resulted in the firestorm. Basically if there is a source of very high temperatures the air in that spot is carried aloft, resulting in air being dragged in from surrounding parts to replace the air that's lost. In this case because of exceptional circumstances these winds are estimated to have reached speeds of 150 mph. Once that starts the effect is self perpetuating until there's nothing left to burn.

    Also, as Jim suggested earlier, in the case of Hamburg the humidity had low for sometime, but that was not a consideration for the raid.

    The same thing happens all the time in nature - cumulus clouds are formed above columns of air rising above heat sources (thermals), and you will find there is often a temporary increase in the surface wind in the vicinity of these heat sources - or as a cloud drifts over.

    Brian

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