Lisø PhD Dissertation Manuscript - NTNU

Fig. 6. Mean winter temperature (ºC, December – February, weather data from the reference 30-year period
1961 – 1990).
Norway also has large variations in snow loads (see Fig. 5). Characteristic snow
loads on the ground varies from 1.5 kN/m 2 in coastal areas in the south up to 9.0 kN/m 2 in
some inland areas (50-year return period).
As documented, Norway has areas with high snow loads (Fig. 5) and high
frequency of wind (Fig. 7). In these areas the wind affects roof snow loads, and the
exposure coefficient is expected to achieve its lowest value. As seen in Fig. 4 the definition
of the exposure coefficient as given in ISO 4355 does not point out these areas as areas
where wind blows snow away from roofs.
Page 12 of 17