Sunlight
The lighting conditions change throughout the year and also depend upon the locations within the country. Here are examples of the sun position throughout the year at Tower Bridge in London and Edinburgh Castle in Scotland. The vertical scale shows the elevation of the sun relative to the horizon and is measured in degrees. The horizon is placed in the middle of the graph at 0°. The horizontal scale is both time (in GMT) and the direction to the sun. All times are in GMT so you will need to add one hour for the summer and Autumn graphs to get to BST. The time of year vastly changes the day length, sun rise and sun set position and elevation of the sun and therefore the length of any shadows. The location within the UK also effects the length of the day as the summer solstice is 16 hours and 39 minutes long at Tower Bridge and 17 hours 36 minutes long at Edinburgh Castle.
What is interesting is the number of hours of daylight each month.
We know that winter days are shorter than summer days. In the winter sunrise and sunset are only eight hours apart (08:02 - 15:59 gmt), of which photographically we can't easily use the hour after sunrise or before sunset as the sun is too low and the shadows are very long. So for December and January the shooting day is at best just under six hours long.
In the summer you get nearly fifteen hours of daylight to work in (04:49-21:20 bst) after you have avoided the hour either side of sunrise and sunset.
The other interesting thing you can find from the historic weather data is the amount of sunshine you actually get. Not just how much day you get but how much sunlight actually breaks through the clouds and shines. A good photograph needs light, with light you get shadows, with shadows you get depth and texture. On overcast days you get nice colours but flat photographs.
I extracted the following information from the historic data collected by the Heathrow weather station. The Daylight column lists the time between sunrise and sunset on the 21st of each month, Usable Daylight avoids the hour either side of sunrise and sunset where the sun is low and you have very long shadows. The percentages that follow are the average amount of time as a percentage of the day length that a Campbell-Stokes recorder registered bright sunlight. These are grouped by decades, and the far right column is the average for the decades as a percentage and as number of hours per day. So if your requirement is bright sunshine in December then you should leave plenty of time as only 20% of the six usable hours of daylight are clear. However of the usable fourteen and a half hours of daylight in June 41% are sunny.
Another way of looking at it is that in December (on average) you have under 6 hours of sunny weather between Monday and Friday, in June (on average) you get almost 30 hours of sunny weather between Monday and Friday.
Months | Daylight | Usable Daylight | 1957-1966 | 1967-1976 | 1977-1986 | 1987-1996 | 1997-2006 | 2007-2016 | Average/day |
---|---|---|---|---|---|---|---|---|---|
January | 8h-41m | 6h-41m | 19% | 16% | 22% | 21% | 26% | 21% | 21% = 1h-24m |
February | 10h-25m | 8h-25m | 20% | 24% | 23% | 27% | 30% | 25% | 25% = 2h-6m |
March | 12h-12m | 10h-12m | 29% | 32% | 27% | 31% | 31% | 36% | 31% = 3h-10m |
April | 14h-10m | 12h-10m | 32% | 37% | 36% | 39% | 39% | 43% | 38% = 4h-37m |
May | 15h-47m | 13h-47m | 41% | 39% | 37% | 45% | 43% | 37% | 40% = 5h-31m |
June | 16h-31m | 14h-31m | 44% | 46% | 36% | 41% | 42% | 35% | 41% = 5h-57m |
July | 15h-50m | 13h-50m | 36% | 41% | 39% | 44% | 44% | 38% | 40% = 5h-32m |
August | 14h-13m | 12h-13m | 38% | 41% | 40% | 49% | 47% | 36% | 42% = 5h-8m |
September | 12h-17m | 10h-17m | 39% | 37% | 38% | 37% | 43% | 37% | 39% = 4h-1m |
October | 10h-23m | 8h-23m | 32% | 31% | 33% | 36% | 36% | 31% | 33% = 2h-46m |
November | 8h-41m | 6h-41m | 22% | 26% | 25% | 27% | 29% | 22% | 25% = 1h-40m |
December | 7h-56m | 5h-56m | 18% | 18% | 19% | 19% | 22% | 21% | 20% = 1h-11m |
The view from Stubbing's Wood in Hertfordshire
Interested in learning more?
If you've looked through my site and have any questions, I'd be glad to help you. You can contact me on my mobile on 07801 103635 or send me an E-mail and I will get back to you as soon as I can.