This picture was taken during a period when Anomalous Propagation (Anaprop) was affecting the Watchman radar.  Atmospheric conditions, probably high air pressure, were refracting the radar signals over their normal horizon, producing 'clutter' on the radar display.  This was in 2010 and the then quite small Walney Wind Farm can clearly be seen as a big 'paint' between the 40 and 50 mile range rings.  In 2017 the wind farm extends to around 25 miles from the Isle of Man and has much larger wind turbines.  Also showing up are the Morecambe Bay gas rigs.
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An Island Images picture © Jon Wornham