Solstice

At 22:43 BST on the June 20 2020 the sun reached the northernmost point in its annual journey north and south across the earth and immediately head back the way it came. This was completely imperceptible to the naked eye of course as it takes six months to travel from one extreme to the other, a distance on the earth’s surface of 3237 miles which is about three quarters of a mile per hour. For a brief moment the sun will, however, appear stationary which is where we get the word solstice from. In Latin, sol means ‘sun’ and sistere, ‘to stand still’. At 13:31 on December 21 it will stand still again when it reaches the southern most point of its journey and then heads north. The sun of course is not really moving up and down the earth. It’s the earth’s rotational axis that tilts at 23.44 degrees to the orbital plane that gives the earthbound observer the illusion of the sun being higher or lower in the sky depending on the time of year. With the sun reaching the highest point in the northern hemisphere sky we have our longest day, or, to be precise, most hours of sunlight per day, in June. It marks the start of summer. I always found it unusual that the warmest weather tended to come after the solstice. The higher in the sky the sun is, the greater its heating effect so you may have thought that warm weather would be distributed equally around the solstice. Seasonal lag though means the higher temperatures tend to come some time after the summer solstice (and coolest temperatures some time after the winter solstice) and this can vary from a few days to a couple of months. The reason is down to the oceans. Water takes longer to heat up and cool down than land and we’ve got an awful lot of the stuff covering the surface of the earth. In effect these oceans act as storage heaters and your best bet for warm weather is sometime after the solstice.

If that’s the case this year then we are likely to be in for a bit of a roasting. Weather-wise, spring has been outstanding in this small part of southwest Scotland, and possibly everywhere else in the British Isles. After a particularly wet winter we’ve had day upon day of sunshine and, until recently at any rate, hardly any rain. This is just as well as in all other respects spring 2020 has been utterly dreadful. Covid-19 has seen to that. A typical Scottish spring would have seen me go crazy in lockdown. The one concession the government made to keeping us sane was to allow ‘exercise’, initially once a day but subsequently as much as you fancied, on the understanding that you keep it local. We have gone for walks on all bar a couple of days since lockdown began some ninety or so days ago. That’s an entire spring of pavement pounding around Troon with the occasional excursion into the surrounding countryside, over 500 miles in total. Most of those walks have been in the evening and thanks to the outstanding weather we have been blessed with we have been able to plot the sun’s slow but steady progress north as it set, initially over Arran and latterly somewhere up towards Largs. Those sunsets have been glorious. With the sun low in the sky the light passes through more air which scatters the blue light away leaving red and yellow light to illuminate any clouds to stunning effect. Much as I love the science involved, I can’t help but marvel just at the beauty of it all, especially with the backdrop of Goat Fell on Arran.

With the sun about to commence its journey southwards the days will get shorter. Seasonal lag should, however, mean there’s plenty of relatively warm days ahead though this being Scotland the wind and rain can trump warm temperatures any time of the year. That they didn’t in spring is almost without precedent. With lockdown restrictions easing just a bit those evening walks may well become less important. Who knows, in a few weeks we may even have the privilege of observing sunsets somewhere else in the world again. We can but hope. In the meantime, I think I’m going to celebrate the summer solstice with a bottle of something mildly alcoholic, raising a toast to the season just ended, both the worst and best spring ever, whilst telling Covid-19 in no uncertain terms to fuck right off.