Solstice: The earth is titled farthest away from the sun

Thursday night, the earth ushered in the shortest day of the year – the winter solstice in the southern hemisphere – the time when, for South Africans, the sun is farthest away.

While some define this solstice as the beginning of summer in the northern hemisphere – triggering all sorts of hippie and quasi-pagan celebrations at places like Stonehenge in southern England – it is the beginning of winter in the southern hemisphere.

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Vox Weather meteorologist Michelle Cordier, however, said they consider the start of winter weeks before the astronomical event today. She said 21 June was considered the longest night of the year but this year “the winter solstice is on 20 June [at 10.50pm]”.

The start of winter

Cordier added: “Because the solstice moment is very close to midnight, both 20 and 21 June will be very much the same length, and we need to look at different time zones to determine which day is indeed the shortest.

“It was referred to as the shortest day of the year. Even though the solstice moment occurs on 20 June, the shortest day would technically be 21 June due to the closer proximity of daylight hours to the solstice time.

“It’s not actually about the length of the day – because each day is pretty much 24 hours long – but the amount of time the sun is visible above the horizon. We could be a bit more precise and say, it is the day with the least number of daylight hours,” Cordier said the solstice happened because the earth tilts at about 23°, which meant one side of the earth was closest to the sun, and the other side was furthest away.

“As the earth does a lap around the sun each year, different parts of the planet get more sunlight than others,” she said.

“That’s why it’s winter in South Africa when it’s summer in Europe. When the southern hemisphere has winter solstice, it’s summer solstice in the northern hemisphere.”

Cordier said meteorological seasons were more consistent, with the four seasons divided into groups of three months; autumn was considered March, April and May, winter was June, July and August, spring was September, October and November and summer was December, January and February.

“By following the civil calendar and having less variation in season length and season start, it becomes much easier to calculate seasonal statistics from the monthly statistics, both of which are very useful for agriculture, commerce and a variety of other purposes.”

Cordier said the longer daylight hours after the winter solstice will gradually start heating the air, ground and oceans.

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Meteorologist Prof Liesl Dyson said because the winter solstice did not have a direct effect on the weather in the short term, it was still winter and still cold.

“The second part of the winter is usually colder than the first. What it does mean is that the sun is slowly returning to the southern hemisphere and will reach the Tropic of Capricorn (23° south) on 23 December,” she added.

South African Weather Service forecaster Tokelo Chiloane said the warmer weather had nothing to do with the winter solstice and was simply due to a weak cold front.

“Winter is characterised by cold fronts, with some cold fronts that have strong effects on the temperatures and some that don’t,” she said.

Chiloane said residents in the interior parts of South Africa can look forward to a pleasant weekend with no surprises or cold fronts forecast.

“As usual, we can expect cold temperatures in the mornings and evenings, with cool and mild temperatures in the northern parts, especially Hammanskraal, where temperatures are forecast to reach 25°C.”

Chiloane added that winter was far from over and warned a cold front could bring temperatures down again.