La dinamica dei ghiacciai   Scheme of ice flow from the accumulation to the ablation area. Snow that falls on the highest zones of a glacier has the longest and deepest travel path. It emerges again at the lowest point of the glacier tongue and is the oldest ice. Depending on the size and flow-speed of a glacier, the travel time of a snow and ice crystal from the accumulation area to the glacier tongue can take from tens to hundreds of years.   ASTER satellite image of 29 May 2002 showing glaciers in the Himalayas, at the border between Bhutan and Tibet (see GoogleEarth file location 1.6). Although this area lies in the subtropics, the glaciers survive. Ice flow transports the ice masses that develop around the cold, snow-rich mountain peaks to the warmer valleys, where it compensates for the intense ice melt.   Animation of two ASTER satellite images of the glacier in the ASTER image. The images are from spring and late autumn 2001. Do you see the glacier flow?   Close-up of animation