Alpenglow

26/11/2014 - 13:01

 

The Sunday afternoon had been spent bouldering (free climbing on boulders) at Combestone Tor with my two children and on a meandering journey back –near Hexworthy - we noticed some alpenglow emerging on the clouds to the east shortly after the sun had set. I saw a potential vantage point and stopped the car on a verge to see if I could make a photo.

 

 

The tiny promontory from which to photograph the vale and moors was a challenge indeed. It was a small tussocky knoll 2metres wide (with a wire fence at its front margin, dropping down into a steep bank) by one metre deep, with a 1.5m high drystone wall below. Two of the tripod legs had to be coaxed through the wire fence and the third managed just to fit on the tussocky grass before the void behind me (rather a steep angle between the tripod’s legs, which is not ideal for stability).

 

 

To accentuate the precarious nature of the situation, an inquisitive donkey had several attempts at nudging the tripod once I had set it at the appropriate angles for my intended composition. It seemed that the donkey had decided this was where the finest grass to eat in the entire rough-pasture had been coincidentally located!

 

 

 

 

 

 

How ungracious of me to turn up at dinner time! Eventually it moved on and I could fine tune my composition again.

 

 

 

Alpenglow lights the fringe of a weather front approaching from the east, above the flanks of Yartor Down and Combestone Tor. The wooded vale is that of the O Brook, a tributary of the West Dart River.

300 metres a.s.l. in Dartmoor National Park

 

 

 

Meanwhile my delightful 5 & 7 year old kids who had chosen wisely to stay in the car and “out of the cold breeze”, had put on the stereo, the headlights, interior lights and heater (I was lost in the moment, with my back to the car)… My reward for the colourful autumnal afterglow frames for the panorama was a flat battery. The next challenge was of  pushing the car’s nearside wheels out of the soft, wet sloping  verge and a further 20m of pushing to gain enough inclination & thus momentum to dive back in the driver’s seat and ‘bump-start’ the engine!

 

 

Ah, the things that go into making a ‘pretty picture’. Sometimes things are not so easily won, but the rewards of observing such beauty are worth it.

 

 

 

* The Science behind the light:

 

Alpenglow (from German: Alpenglühen) is an optical phenomenon in which a horizontal reddish to pink glowing band is observed on the horizon opposite to the sun. This effect occurs when the Sun is just below the horizon. Alpenglow is easiest to observe when mountains and high hills are illuminated but can also be observed when the sky is illuminated through backscattering.

 

Since the Sun is below the horizon, there is no direct path for the light to reach the mountain. Instead, light reflects off airborne snow, water, or ice particles low in the atmosphere. These conditions differentiate between a normal sunrise or sunset and alpenglow.

 

 In the absence of mountains or high hills, the aerosols in the eastern portion of the sky can be illuminated in the same way at sunset by the remaining red scattered light straddling the border of the Earth's own shadow (the ‘terminator’ - the line that separates the portions of the Earth experiencing daylight from the portion of the planet experiencing darkness.). This back-scattered light produces a reddish/ pink band opposite the Sun.

 

 

Technical info:

Pentax K-x

Pentax 18-55mm SMC/ DAL lens

Cromatek Circular Polarizer & 2-stop Neutral Density Graduated Filter

Manfrotto XProB Tripod & Ball Head 49RC4

Aperture = f/11

Exposure Duration = 1 second (per frame)

ISO = 200

Manual

This is a panoramic stitch of two individual frames.

 

 

Fine Art Panoramic Giclee Prints in museum grade mounts are available here

 

 

 

 

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