Professor Chronis Tzedakis (UCL Geography) said: «The basic idea is that there is a threshold for the amount of energy reaching high northern latitudes in summer.
«At the higherlatitudes of Great Britain, Scandinavia and the Baltic States, as well as Northern Germany and France, very little UVB light reaches the Earth, and it's the key wavelength required by the skin for vitamin D generation,» Elias said.