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solstices — extremes of light and dark
O rkney summers are long, with almost
continual daylight. In June, for example, the sun is above the horizon for
over 18 hours. This is contrasted sharply by the long, dark, winter
months, when the sun rises after 9am and begins to sink beneath
the horizon again around 3.30pm.
This is due to the high latitude
of Orkney (59 degrees north).
At the midsummer
solstice, the sun rises in the north-east, around 4am, before setting
again, in the north-west, at around 10.30pm. As such, the sun shines
for six hours on north facing surfaces and is in the sky for some
18 hours.
But despite the long summer
days, the altitude of the sun at noon is less than 60 degrees, so
high temperatures are unusual.
When the summer sun finally
sets, it remains just below the horizon so there is no true darkness
- simply a period of extended twilight, known in dialect as the "simmer dim".
But there is a price to pay for the long hours
of summer light.
By the time of the winter solstice, in December,
the sun is rising in the south-east after 9am, setting around six
hours later in the south-west.
During this "day" of weak, grey light,
the sun barely reaches a midday altitude of ten degrees. What sunshine
there is is dependent on the cloud cover at the time, which
can often make for days of near darkness.
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