Dartmoor Gliding News-Sunday 11th December 2016

On arrival today the club was buzzing with activity (not all of it productive – about which more later…) as we made arrangements to change ends for the light westerly wind that was forecast. The sun beamed down on the gliders laden with dew which appeared more like golden champagne bubbles than water.

K-13: During tow-out the conditions were champagne sparkling...
As we made the long walk to the other end we could see the fingers of mist clinging to the river valleys that would shortly be ‘burned off’ by the winter sun. And then something happened which no-one predicted. Cloud. Lots of it. First, at the launchpoint, then over the winch and west end. Then, it cleared … and then returned. And so we waited for the sun to do its work. And waited. Until as the long tall tales and jokes began to peter out, we began to wonder why. Until, at CFI Don Puttock’s prompting, we began to look at RASP and the dew point. The weather station in the launchpoint gave the outside air temperature as being 11oC. Now you normally expect the dew point to be something most people would recognise as ‘cold’. Today, RASP forecast a dew point at 1200 to be 8.5oC – yes 8.5oC! Almost tropical… Allow a little room for error (both on the reading in the launchpoint and the forecast), plus the usual dry adiabatic lapse rate, and you could see that cloud could most possibly form at a little over 200ft above the airfield, particularly as the air was being pushed inland and uphill by a southerly breeze.

Church and windsock: And the reverse angle reveals a similar situation to the west.
Orographics, then. And with the Met Office saying “‘TIL 13Z”, surely there was time to retire to the clubhouse to enjoy Roger Appleboom’s stollen cake (sadly no photo) before returning to fly in the afternoon. Except ‘TIL 13Z’ meant that a moderate blue hole would appear at about 14Z, only to be swamped by yet more orographics as they swept up the hill. So no flying today.

 Zugvogel:...and then the orographic rolled up from the south.
To turn the unproductive activity mentioned earlier: those of you with (not necessarily all that) long memories will recall that is was quite usual to turn up at any gliding club to find people, not busily pulling out the gliders, but poring over some piece of heavy machinery that either refused to work, had started but now stopped or was flat or was otherwise u/s. Well today the machinery in question was one of the Land Dover Discoveries, which wouldn’t start. So a battery was despatched from the red Discovery, which did the trick. But upon returning said battery to the gold Discovery, then wouldn’t turn the engine over! So the question in our ‘And finally ‘push me/pull you photo is: Which Disco is pulling which? (Answers on a postcard please).

A typical gliding club scene: but which Land Rover's pulling which?

Martin Cropper

1 comment:

Rich Roberts said...

Not sure what way the land rovers are pulling. My main question is does Heather know someone else is driving her discovery!!!