Through the Solstice

The winter solstice is the period around the shortest day, 21 December [1]. It is a turning point in the annual solar calendar. In the tradition, the winter solstice is a time of renewal, the turning of the year.

Today in northern latitudes, midwinter is a time of family and festivals. Food is in the shops, much of it imported from a global food system. Yet midwinter was very different 5000 years ago in the late neolithic when the early settlers to these islands began to farm. They could not import: they had to grow their own or go hungry.

The arrival of the solstice reminded them how long they had to last on stored grain and livestock. They could add to their diet from wild harvesting and hunting, but once people had committed to a settled existence, they needed grain and grass to ensure their survival.

Three more months at least before the soil was warm enough to sprout fresh grazing and germinate sown seed to give next year’s grain. This lag between the annual cycles of solar radiation and temperature is a defining feature of agriculture in the north. Farming has to cope with it now, as then [2].

They first farmers built great stone monuments to help them follow the solar and lunar cycles. Some, such as at Maes Howe in Orkney and Balnuaran of Clava near Inverness, were designed to mark or to celebrate the winter solstice [3].

Fig. 1 Daylength at the winter solstice, 21 December, at a range of archaeological and historical sites. Hours:minutes shown are from sunrise and sunset tables for 2020, excluding twilight [4]

Daylight hours

When neolithic and bronze age people were making their way across Europe, they experienced the large change in the length of day and night from south to north (Fig. 1). For example, daylength at the neolithic site of Carnac in Brittany (8:26) is two hours longer than at Callanish on Lewis (6:24). At the northern tip of Shetland, it is 5:40 and much farther north in Iceland, around 4 hours.

The length of day determines what can be done outside without torches and street lights. The order reverses in summer – much more daylight in the north than south. The effect of the latitudinal change on life and lifestyle was (and is still) huge, but the early settlers balanced one thing against the other. They crossed dangerous seas to settle and survive throughout the range of daylength, including areas that even today seem remote to most city people.

The standing stones at Brodgar and Stenness, in the Heart of Neolithic Orkney, lie close to the Maes Howe chambered cairn, whose entrance passage is aligned with the setting sun at the winter solstice. [3]
Sunrise, sunset and the three twilights

It would be difficult in most years, even with the aid of aligned monuments, to tell exactly when the shortest day had arrived. Daylength changes very slowly in mid to late December, and the position of the sun is often obscured by cloud or mist. Two other factors make the estimation more difficult – twilight and the shortest day not coinciding with the latest sunrise or earliest sunset (Fig. 2).

Light from the sun is still visible even after it dips below the horizon. This is the time of twilight, of which there are three divisions – civil, nautical and astronomical. The boundary between them is defined by the angle the sun (below the horizon) makes with the earth’s surface [4]. Most people sense night has fallen near the end of civil twilight, but under a cloudless sky it is also possible to ‘see’ well into nautical twilight.

Fig. 2 Change in length of the day and types of twilight (civil, nautical and astronomical) for 40 days either side the shortest day (SD) on 21 December. The earliest sunset (e ss) is about seven days before SD and the latest sunrise (l sr) 7 days after SD. Location: Inverness, latitude 57.5 north.

Civil twilight at the winter solstice varies with latitude less than daylength. For example, it ranges from about 40 minutes at Silbury Hill in Wiltshire to about an hour at Funzie Girt in Shetland .

There is also the complication that the latest sunrise and earliest sunset do not coincide with the shortest day (Fig. 2). The reasons are complex and depend on the axial tilt of the earth and its elliptical (not circular) trajectory round the sun [5].

The photograph above shows two trees on the Hutton Farm near Dundee in 2010. It was taken after the end of civil twilight and well into nautical twilight. The original image was almost black, but shape and colour were revealed by digital processing.

Solar elevation and the sun’s intensity

The growth of crops and grass depends on the amount of solar energy reaching the earth’s surface rather than on the period of light. Daylength has an effect – it determines when some plants change their state, for example from vegetative to reproductive – but plants put on mass by capturing solar energy and using it to process carbon dioxide from the air into living matter.

The incoming solar energy increases from winter to summer solstices as a result of both increase in daylength and increase in the sun’s ‘height’ in the sky, defined as its elevation or altitude [Fig. 3]. Between winter and summer solstices, daylength increases about 2.6 times, while the sun’s elevation or altitude increases 5.6 times. (These values change with latitude – those cited are for Dundee near latitude 56N.)

The combination of longer days and rising altitude causes a 20-30 times increase in the incoming solar radiation reaching crops, grass and forest between the winter and summer solstices [6]. This, and the annual changes in temperature and rainfall, are the major factors that determine which types of crop and grass grow here, the times they can be planted and harvested and the yields they can attain.

Fig. 3 Diagram to show the changes through the year in the rising and setting of the sun and its elevation or altitude at latitude 56N. The horizontal axis shows the time of day, the vertical axis the elevation or altitude of the sun (90 degrees would be directly overhead). The lower curve is for the winter solstice, the upper for the the summer solstice and the middle for the equinoxes [6].

Sources / links

[1] The winter solstice is defined in astronomy as a particular time on usually 21 December, but it is also used widely to mean the period of several days around the shortest day.

[2] Living Field web pages on The Year describe the changing annual cycles and their importance for farming and food production.

[3] Maes Howe, Orkney: Orkneyjar; for archaeological detail, Canmore; to see the solstice, Maeshowe webcam site. Balnuaran of Clava: Historic Environment Scotland; Canmore. See also the Winter solstice on the Living Field site.

[4] Daylength, twilight times and solar elevation are available online for almost anywhere on earth. One of the easiest web sites to use, and the most informative, is timeanddate.com – insert a named place where indicated to see daily data tables; once there, you can use the map facility to find any place. Try also NOAA Solar Calculator provided by the US Global Monitoring Laboratory.

[5] For explanation of the earth’s tilt and solar trajectory, try: Articles about Sun at timeanddate.com; a BBC Weather page; the explainingscience blog. For a thorough and authoritative account: Szokolay S.V. 1996 (rev 2007). Solar geometry. Passive and Low Energy Architecture International (PLEA) and Department of Architecture, University of Queensland.

[6] The Living Field article No Life Without the Sun gives further explanation of the effects of daylength and solar elevation on the changes in incoming solar radiation throughout the year.

Common Grains | Seed Sovereignty

The Living Field has supported local crop landraces and traditional varieties. We have grown them, saved their seed, used their products to make food, promoted them on open days and shared them with growers and gardeners.

Grains are the staple diet of any settled population. Neolithic ancestors brought them to these islands thousands of years ago. People sustained themselves on locally grown grain crops such as oats, wheat and barley. This is no longer the case. Most of our grain foods are now imported, apart from oats which occupies a small area of arable land, and a few fields of special barley and wheat. We are highly vulnerable to loss of this essential staple food through blockade or import restriction.

So it is specially good to hear the continued and growing interest in projects like Common Grains [1] and Seed Sovereignty [2]. They operate outside the conventional channels of crop varietal breeding and depend on local and often unfunded commitment for their success. Here we pass on some recent news and upcoming events from both projects – with images of the Living Field‘s cereal landraces and some old methods of grinding and milling grain.

A landrace of bread wheat Triticum aestivum (left) and grain, spikelets and flowering stems of black oat Avena strigosa (right) grown at the Living Field near Dundee.

Common grains

With emphasis on both growing and baking, Common Grains is showing that short food chains work. It aims to reduce the physical and commercial distance between seed, crop, harvest, (saved seed), processing, baking and eating. As a result, the eater will likely appreciate the growing and have an vested interest in soil health and biodiversity .

Common Grains is developing ambitious annual and five-year plans, where again the joint emphasis is on growing grains and supplying nutritious food. Several farmers are experimenting with crop mixtures as a means to reduce inputs and improve the agricultural environment.

A summary of their conference in late 2019 is given on the We Knead Nature web site [1]. Long term plans include a hub for growers, customers and businesses, a Seed Bank of local saved-seed grain crops, and greater community engagement through formal education and kitchen skills. Contacts through Facebook and Instagram [1].

Ears of rye Secale cereale at the Living Field (left) when about to flower (upper, middle) and when mature (lower), and bere barley Hordeum vulgare (right) growing in Orkney (lower) and maturing at the Living Field near Dundee (upper).

Seed Sovereignty UK and Ireland Programme

The Programme’s web site explains its aims and purpose: “The Seed Sovereignty Programme of the UK & Ireland aims to support the development of a biodiverse and ecologically sustainable seed system here on home soil. Working closely with farmers, seed producers and partners across the seed sector, together we want more agro-ecological seed produced by trained growers, to conserve threatened varieties and to breed more varieties for future resilience.”

One of the main aims of the project is to establish regional and national hubs, networks and collaborations. Contact details of regional coordinators are given on the web site’s About page [2]. Activities include raising the main issues and current difficulties around saved seed, encouraging networks and support hubs, training, databasing, field trialling and participatory plant breeding.

There’s an upcoming Seed Week. Sinéad Fortune, Programme Manager, writes “From 18th – 22nd January Gaia will run our fourth Seed Week, which aims to raise awareness of local, open pollinated, agroecological seed being grown and sold in the UK and Ireland. The timing coincides with growers shopping for seeds for the coming season, and we hope to raise general awareness of the importance of agroecological and locally-grown seed with a wider audience.”

There’s ample opportunity to get involved and if you use social media then here is the tag #SeedWeek.

Methods of grinding grain through the ages: (upper left) saddle quern from neolithic Shetland, (lower left) hand-turned milling stones from Orkney, the meal swept into the container below, (upper right) water powered mill wheel (under wooden cladding) from Atholl Perthshire and (lower right) a wooden bushel measure used for grain and flour, again from Orkney (images courtesy of curvedflatlands.co.uk).

Sources / contacts

[1] Common Grains is on Facebook and Instagram. A note on the Common Grains Conference Scotland in 2019 is published on the We Knead Nature web site. Thanks to Rosie Gray for recent updates.

[2] Seed Sovereignty contacts and information. Sinéad Fortune, Programme Manager, Seed Sovereignty UK and Ireland Programme sinead@gaianet.org. Web sites: http://www.seedsovereignty.info/ and http://www.gaiafoundation.org/. For previous Living Field contact, see Maria Scholten’s article Boosting small-scale seed production .

[3] Landrace is the term usually given to a crop that is maintained from year to year through saved seed. For more on this site: What are landraces?, Landrace 1 Bere and Ancient grains at the Living Field.