Saturday, October 11, 2008

How Far Can You See?

Not without good cause most vis watchers that I know locally have an avid interest in the distant horizon. This can of course be for several reasons, two of which are:

A general interest in the topography and geography, or possibly more likely:

Familiarity through necessity, to be able to describe to others at the watch exactly where they are seeing a bird in the sky and also to be able to get onto the bird that someone else is trying to describe, i.e. over Buckden Pike doesn't mean that the bird is actually over Buckden Pike, some 44km distant, but just that, that's where to look to see the bird in the sky! And it nearly always works - especially with the scope sight in use. Another example would be "just going west past Bilsdale West Moor", this being the Tyne Tees TV transmitter mast, at some 80km distant!, or even over the Humber Bridge!!!

If you don't know the horizon topography, you would soon get to know it at one of our vis watches here as it is an absolute necessity, and one of the basic principals of inland vis watching, where there are more than one pair of eyes. Even the cloud types, formations and their edges are with experience becoming useful as guide pointers.

Following is a brief description of the topography and horizon as seen from our watchpoint at Oxenhope, both out of interest and to aid those who occasionally watch with us here, are yet to come, or follow on.

It should be noted that it has been found recently in exceptionally clear conditions that the following schedule is not fully complete as new wind turbines as well more distant church spires, chimneys and large buildings on the horizon all further away than described have been seen..... We are working on the location and identification of these!

Traversing clockwise and starting at WEST, all heights are in ft and distances in km. This might sound a comical combination of metric and imperial units butas cloud-base heights are recorded in feet it gives the following appraisal anadditional use. It is mainly the far distant horizon which is described:


Due west (the direction of the Ribble Estuary) is Cock Hill at 1425ft some 3.5km distant, where Nick did a few watches earlier in the season. This view is overNab Water col, which bottoms out at+++++++, a considerable north - south gapthrough the Aire-Calder watershed. Here, on the top, there is a disused radar tower and mobile phone mast. From here the Aire-Calder watershed traverses to the north-west, with a series of moorland tops (from at least one of which -Oxenhope Stoop, the Lakeland hills can be seen) gradually increasing in height until Jacksons Ridge (the Lancashire - Yorkshire border and east west watershed) is reached at Crow Hill (1501ft) beyond Haworth and Stanbury Moors, some 9.5 kmdistant. Prior to this the summit of Boulsworth Hill (Lad Law), 1700ft @ 12.5km again on the Lancashire - Yorkshire boundary, protrudes boldly above the nearer horizon. From Crow Hill, Jacksons Ridge drops north-eastwards into theWatersheddles col, a south-east to north-west gap across the South Pennine hills and into Lancashire. This col is almost due north-west from us at about 1100ftand 10km distant. Over the upper Worth basin and through the col we can see,firstly the Easington Fells at about 35km distant, over Stocks Reservoir (which cannot of course be seen) with the Bowland Fells in excess of 45km beyond. On this flight line lies Morecambe Bay with Walney Island beyond. In the neardistance and lower in the upper Worth basin lie the reservoirs of Leeming andLeeshaw.

NORTH-WEST to NORTH (two more distant hills yet to id)

Out of Watersheddles col, the ridge of Combe Hill, Ickornshaw Moor and KeighleyMoor rises in a north-easterly direction to the Wolf Stones summit at 1455ft, some 10km distant from us. From here (not from the watchpoint) on the Lancashire- Yorkshire border, the backbone of England, one can see out to the west coastand beyond, with the coastal view, starting on the Fylde, just north ofBlackpool, with the Tower sticking up like a match stalk, round and up the "V"of the Ribble Estuary, round the bulge of the Southport coast down southwards and on a very clear day across the sea to the Welsh mountains and Snowden. The flat summit of Keighley Moor extends a little way north-east before falling away a little down onto the lower Sutton Moor c1100ft at still c 10km distant. On Sutton Moor the Hitchin Stone, Salt and Pepper Pot monuments can be seen and they over look Airedale below. From here northward the view opens up into the Yorkshire Dales. Beyond Sutton Moor, lies Elslack Moor (1274ft), some 19km distant. Beyond Elslack and the most distant ridge to be seen in this direction lies the southerly extending arm of the Leck Fells at about 60km distant, beyond the south flank of Ingleborough. Just a little nearer than this and in the same direction, the flat topped mass of Ingleborough rises to 2373ft at some 53km distant. Again beyond Elslack but in front of Ingleborough lie the Settle scars, knots and Sugar Loafs, these are about 38km distant. From here rises the northerly extending Langcliffe ridge, with the progressively higher tops of Ryeloaf Hill, Great Scar, Fountains Fell and finally flat topped and southerly scared Penyghent at 2278ft high and 48km distant. When visibility is very clear both the tops of Malham Cove and the Gordale Scar can be seen as detail on the east flank of these hills. Beyond the Langcliffe ridge and between the summits of Ingleborough and Penyghent lies the summit of the third peak, Whernside at 2414ft high and 60km distant. Whernside is the highest hill that we can see fromthe watchpoint. In front of the Langcliffe Ridge and projecting above and beyond the flat top of Sutton Moor lie the two, peaked Flasby Fells. These are at about25km distance. Further round to the north and in the mid distance is the mass of Rylstone Fell and Barden Moor with summit of 1661ft and 29km distant. Beyond this lies the summit of Buckden Pike 2302ft at some 47km distant and on the Ure- Wharfe watershed. As the distant ridge progresses eastward Great Whernside,2310ft, 41km distant and on the Nidd - Wharfe watershed becomes prominent, followed by the progressivly lower Meugher and Stonebeck, being immediatelynorth of Grimwith Reservoir, the largest area of inland water in Yorkshire. The west end of the Grimwith embankment can be seen and lies 31km away, immediately beyond the Chelker wind turbines and to the due north of the watchpoint. Thereare large Gull roosts at both Chelker Reservoir (18km north) and Grimwith which are both due north from the watchpoint. In front (to the south of) of Rylstone Fell and much lower down lies Skipton Moor at 18km distant. This is the westernend of the north-west to south-east watershed that separates mid Airedale from mid Wharfedale. Cringles col at 16km distance splits this ridge between Addingham on the Wharfe and Silsden on the Aire and again this is almost due north from the watchpoint.


The view in this direction looks out over the lower Worth valley and mid-Airedale, with the towns of Keighley (due north) and Bingley (north-east) both in the bottom of Airedale and both lying at about 8km distant. In the very near distance lies Sentry Hill, only 600m away to the north. Between Sentry Hilland the watchpoint lies a shallow col between the Stubden Beck valley and the upper Worth basin. Further north in this direction and on the watershed between the Worth and Harden Beck vallies, lie Black Moor and then Harden Moor, 879ft and 7km distant. On the north flank of mid Airedale lies Rombalds Moor which forms the north-west to south-east watershed that separates mid Airedale from mid Wharfedale. The full length of this moor between Cringles col to the north and Glovershaw Gap to the north-east is visible, with ridge at between c1000 -1323ft and 14km distant. Towards the eastern end of this ridge the Bilsdale West Moor, Tyne Tees television transmitter mast can be seen projecting considerably above the horizon, from the south flank of the Cleveland Hills, beyond the Vale of Pickering at about 81km distant. As the ridge of Rombalds Moor begins to fall away to the south-east at its eastern end, the Cleveland Hills, actually become visible and Bransdale and the Westerdale Moors can be seen at 1422ft and 90 -95km distance (only 20 - 25km from Teesmouth beyond). The view of the North YorkMoors is then broken by Lindley Moor, some 1000ft high at 25km distance and on the north flank of the Washburn valley. This is topped by a considerable andprominent transmissions tower at Norwood Edge.


Immediately to the east of Lindley Moor and slightly lower lie Sandwith and Stainburn Moors. Beyond these the view again opens out into the North York Moors, with Sutton Bank and the White Horse of Kilburn showing well at 981ft and 70km distant. Year by year as the conifer plantation grows on the nearer horizon, less and less of the White Horse beyond can be seen and the fifteen years since I started to watch from this watchpoint has made a big difference. To the east of Glovershaw Gap, a considerable north -east to south-west col, from Wharfedale into Airedale is Baildon Moor (or Hope Hill) at just over 900ft highand 11km distant. A little more distant lies Otley Chevin 841ft and 20km distant, again on the Wharfe - Aire watershed. The Chevin ridge continues to the south-east and reduces to c680ft, where Leeds and Bradford International Airport is found some 19km distant at Yeadon on the high land, north of both Leeds and Bradford. Beyond the southern end of the airport and Cookridge Tower lies Eccup Reservoir, where there is an other large gull roost. Also beyond the south end of the airport at 58km distant lies York, where the tower of the Minster can be clearly seen. Further beyond this at 600 -700ft, 88 - 100km distant lies the scarp of the north end of the Yorkshire Wolds, with Scarborough being only c20km distant. From the north of this, the ridge of the more distant North York Moors runs into the ridge of the Yorkshire Wolds and this can be followed across and beyond the Plain of York and seen in detail when visibility is good right the way down to the south extent and their scarp down to the north bank of the Humber at Brantingham. As a generalisation the ridge of the Wolds is between 90-100km distant and max 808ft high. In clear conditions the towers of both Beverly Minster and Selby Abbey can be easily seen. Due east of the watchpointlies the centre of Bradford in its basin at 11km, the Pudsey ridge, 602ft, 18km (the high land between Bradford and Leeds), the centre of Leeds at 25km and beyond that the higher land at the eastern extent of the Pennine foothills around Garforth and Kippax at c250ft high and 35km distant. Beyond that the flatland stretches far out to the Humber estuary.


Just south of east lies the Humber Bridge at 102km distance, on the middle Humber. The north tower can be seen in isolation and when the visibility is clear, both cateneries and suspensions can be seen. When dark, if you know where to look, even the warning lanterns on the bridge can be made out. The south tower is seen amongst and beyond the cooling towers of Drax power station at Goole some 65km distant. The cranes and lifting gear at Goole docks are very prominent. Slightly further round to the south than this, but nearer, lie the cooling towers of Eggborough power station at 53km and further south of this again and progressively nearer is the Ferrybridge power station, again with its cooling towers at 45km distant and almost adjacent to the RSPB Fairburn Ings nature reserve to the east of Leeds. All of the fore going power stations are coal fired. In the Far distance, to the south of the Humber, probably beyond Scunthorpe, 86km, and into the foothills of the north Lincolnshire Wolds lie two very considerable box like structures. These are thought to be the Keadby, Brigg or South Humber Bank CCGT power stations but further research is needed to confirm!! To the south of these the Ridge of the north Lincolnshire Wolds extends southwards until it is lost behind the nearer horizon of the hills on the Aire-Calder watershed which rise to the south of Bradford. Just briefly to the south of this can the Lincolnshire Wolds be seen again through a col just tothe north of Back Lane, Clayton, at c950ft and 7km distant and over the Horton Bank Top reservoir. At this point the Lincolnshire Wolds are some 145km distant(108deg without magnetic variation) ESE and the Belmont, the ex Anglia television transmitter mast here, just north of Donnington on Bain can be seen well projecting above the horizon of the Wolds when the visibility is clear.This, at 145km, is the most distant known point that can be seen from thewatchpoint. The near horizon south of here quickly rises to the summit ofQueensbury Mountain, on the Aire-Calder watershed, 1207ft at 5km distant SE.


If one goes south-east to ultimatum in the UK, the Wash is reached. The south-east view here is directly down the line of the reservoir embankment, some 900m long, across the in-bye of Black Edge, Foreside and the Causeway Foot col, towards Soil Hill, 1320ft high at 3.5km distant. The Causeway Foot col is a very considerable gap through the Aire-Calder watershed, from north to south. It bottoms out at c1150ft and is between Soil Hill to the south-east and the Moor to the north-west. It appears as a very considerable gap in the watershed when viewed from many miles to the north. The entire view over this sector lies beyond the water of the reservoir in the foreground. Looking south of south-eastand through the Causeway Foot col the Yorkshire Television transmitter mast at Emley Moor is prominent as it rises up considerably over and above the south-east end of the reservoir. Emley Moor is 32.5km distant. Further found to the south, the in-bye rises gradually along the Foreside ridge at c1.5 to 1.1km distant and obscures any view to the south. The ridge of Thornton Moor continuesto rise and at due south it has reached 1372ft at 900m distant.


Just west of south lies Hambleton Top at some 1400ft and 600m distant. Beyond here, over the other side of Ovenden Moor 4km distant lie the Cold Edge Dams where Brian was based this year. The ridge of the Moor continues to rise as it progresses round to the south-west, past the flat top of Sawood Moss and nearby redundant quarry delvings, until it reaches the multi cairned top of Oxenhope Nab, this is at 1480ft and 1.8km distant and lies just west of south-west. Beyond Sawood Moss is the Ovenden Moor wind farm which holds 23 turbines, the nearest of which is c1900m distant. Only the tips of the nearest turbine can be seen rotating over the top of the hill and beyond the Moss.


At Oxenhope Nab the ridge of Thornton and Oxenhope Moor (East) comes to an abrupt halt as the land plunges down into Nab Water col, another very considerable col, N - S through the Aire-Calder watershed, again visible from many miles to the north. The col bottons out at ++++++. South-west beyond theNab lies Fly Flatts reservoir, some 2.6km distant. This reservoir has only limited interest to a birder owing to 100% use by a sailing club. Towards the west Oxenhope Moor (West) rises gradually towards Cock and Stake hills and this is where we came in.

JUST OUT OF INTEREST and to help with further study....

Here are some links which will help one to identify and locate some of the man made structures which can (must be able to) be seen from virtually every vis watchpoint. These as well as the known hills and mountains can be used as very accurate visibility distance markers. The distance to be recorded in viswatching should be the maximum to be recorded at which you can see /differentiate an object, ie just as the birds can see it and wayfind? By it.

Please note whilst using the following links that I have found whilst using them that not only some of the wind Farm locations are incorrect but that the television and terrain mapping programmes are only approximate ie Belmont TV transmitter mast is from us 144.36km distant at 108.15 deg (calculated by me), the programme gives results of 126.5 km and 112deg, this worried me when first using it as I knew what I was looking at and that it was at c108deg. This by calculation I proved to be correct. An inaccurate result is also given for the Emley Moor mast, but the Bilsdale West Moor mast is ok...... So use with caution and do calculate the critical distances your self.

Try the terrain mapper (megalithia), its great!!
Here are the links. If anyone knows more do please post as I havent put a lot oftime into finding these.



and for a map:


UK Newclear Power Stations:





And for a suite of old programs that can draw terrain maps and horizon views andthings like that try



LIGHTHOUSES (there must be more links than these which give the technical info,does anyone know?)





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