MODEL RELEASED. Measuring snow density at a weather station in Swedish Lapland. A known volume of snow is placed in the container and weighed, allowing its density, and therefore its water content, to be calculated. This is done to work out the mass balance of the region's glaciers. This is the difference between the amount of snow accumulation during the winter and the amount of meltwater lost during the summer, which allows quantification of the effects of climate change. Photographed at the Swedish Met Office's (SMHI) station at Tarfala. Measurement of the nearby Storglaciaren glacier began in 1945, making it the world's longest mass balance record. Photographed in April 2006.