The long summer evenings are disappearing quickly, with Ayrshire currently losing around four minutes and 25 seconds of daylight every day.
Meteorological autumn begins tomorrow, Tuesday, September 1, while astronomical autumn will arrive with the autumn equinox during the early hours of Wednesday, September 23.
In Ayr, the sun rises at approximately 6.22am today and sets shortly after 8.15pm, providing just under 14 hours of daylight.
By the end of September, sunrise will be around 7.19am and sunset at approximately 6.57pm, leaving Ayrshire with only 11 hours and 38 minutes of daylight.
That means we will lose around two hours and 15 minutes of daylight during September alone.
How quickly is the daylight disappearing?
Each day: around four minutes and 25 seconds
Each week: approximately 31 minutes
During September: around two hours and 15 minutes
Since the summer solstice: approximately three hours and 35 minutes
Between the longest and shortest days: around ten hours and 25 minutes
Scotland experiences a more dramatic seasonal change than southern parts of the UK because it sits farther north. Northern Scotland enjoys exceptionally long summer evenings, but it also loses daylight more rapidly as autumn approaches.
Autumn does not have just one starting date
There are actually three ways of deciding when autumn begins.
Meteorological autumn starts on September 1 and runs until November 30. This fixed system makes it easier for weather experts to compare seasonal statistics.
Astronomical autumn begins at the equinox, which this year occurs at approximately 1.05am on Wednesday, September 23. This is when the Sun crosses the celestial equator and illuminates the northern and southern hemispheres almost equally.
There is also phenological autumn, which is measured by changes in nature rather than by a date. Signs include leaves changing colour, berries ripening, birds migrating and the first leaves beginning to fall. Royal Museums Greenwich
Day and night are not exactly equal at the equinox
Despite the word “equinox” coming from Latin words meaning “equal night”, daylight on the equinox lasts slightly longer than 12 hours.
This is partly because the atmosphere bends, or refracts, sunlight, allowing us to see the Sun briefly before it has physically risen above the horizon and after it has technically set.
The date when daylight and darkness are closest to being exactly equal is called the “equilux”, and it normally happens in Scotland a few days after the autumn equinox. Met Office
The evenings are shrinking faster than the mornings
During September, sunset in Ayrshire moves from shortly after 8.10pm to before 7pm. At the same time, sunrise moves from around 6.24am to approximately 7.19am.
So while both ends of the day are changing, we tend to notice the loss more in the evening because sunset is moving earlier by roughly two-and-a-half minutes each day.
The clocks will make the biggest visible difference
British Summer Time ends on Sunday, October 25, when the clocks go back by one hour.
It does not change the actual amount of daylight, but it moves an hour of available light from the evening to the morning. In Ayr, sunset on October 31 will be at approximately 4.41pm.
The shortest day is still nearly four months away
The winter solstice falls on Monday, December 21.
Around that time, Ayr will have only about seven hours of daylight, with sunrise close to 8.45am and sunset shortly before 3.50pm.
Interestingly, the earliest sunset and latest sunrise do not happen on the winter solstice itself. In Ayr, the earliest sunset comes around December 14, while the latest sunrise is around December 29. This difference is caused by the Earth’s orbit and the way our clocks measure a standard 24-hour day. Ayr sunrise and sunset data
Autumn can be a good time to see the Northern Lights
The weeks around the autumn equinox can improve Scotland’s chances of seeing the aurora borealis. Geomagnetic activity tends to be stronger around the spring and autumn equinoxes, while Scotland also benefits from increasingly dark skies.
Nature is already preparing
Shorter daylight and cooler temperatures cause deciduous trees to reduce their production of chlorophyll, the pigment responsible for green leaves. As the green colour fades, the yellow, orange and red pigments already present in the leaves become visible.
Late August and early September are also prime times for blackberries. Rowan berries, elderberries, rosehips, sloes and hazelnuts become increasingly noticeable as birds and animals prepare for winter.
Swifts and swallows begin travelling south, while redwings, fieldfares, geese and several species of duck will soon arrive in Scotland from colder parts of Iceland, Scandinavia and northern Europe. Woodland Trust
So, although summer is not disappearing overnight, Scotland is currently losing roughly half an hour of daylight every week, and the change will become increasingly noticeable throughout September.