One of the things we go through for final-year students studying the Physics of the Climate system is the geometry that allows you to calculate how much sunlight you get at a given latitude on a given day of the year.  The result looks like this.


Up here at 56°N we get less than 5 MJm-2 at midwinter and more than 40 MJm-2 at midsummer. Which is all very well in a general sense, but it doesn’t really apply to my garden, which slopes downwards towards the northeast, has high walls, and has some fairly tall buildings to the south and west. This means that there are a couple of months either side of midwinter where it gets no direct sunlight at all. Not at ground level, anyway. From the insolation point of view it might as well be north of the Arctic Circle, although the proximity of the North Sea means that it doesn’t have an Arctic temperature range.midday

This is about 12:30 on 4 January; the sunlight has got about halfway down the wall and is rapidly departing again. The ground (and the greenhouse) have not seen a single un-scattered photon. I’m looking forward to the day sometime in March when sufficient sunlight comes back into the garden and it all starts growing like mad.

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