17 December, 2005

Sun lite

Why is daylight so 'thin' at this time of year?  I was in the Lune Valley today, and noticed that whilst objects in direct sunlight were brightly, even harshly, illuminated, anything out of direct sunlight was very deeply shadowed.  The lee side of a typical hedge was downright dark.

The height of the sun is obviously rather important (at 54°N, five days from the winter Solstice, it's low in the sky even at midday), but there seems more to the quality of the light than that.
Could it be that in summer, atmospheric haze seems to diffuse the light and soften shadows, whereas the same haze in December merely blocks the weaker light?
Might the fact that solar radiation passes obliquely though more of the atmosphere than in summer affect the amount and spectral qualities of light reaching the ground?