Winter varies all over the world. If you are near to the sea you may have cold periods separated by warm ones. In those conditions any snow that forms turns partly to slush and rivers rarely freeze over completely. But if you are far away from the seas and in the middle of a big continent like Asia, then the cold, clear weather remains for months on end. In these conditions, rivers freeze over. In the past people used to ski on the frozen rivers, but now, as well as skiing, the frozen river waters are used to make ice sculptures. In parts of China the remarkably cold weather lasts for months. This allows Harbin, China, to host the world's largest Ice and Snow festival.
Harbin is in Northeastern China and gets its cold winter wind from Siberia. The average temperature in summer might be a warm 21.2 °C (70.2 °F), but it falls like a stone to a numbing –16.8 °C (1.8 °F) in winter.
The festival begins on January 5 and lasts for a month. There are two main areas: Sun Island, which is where there are the most enormous snow sculptures; and Ice and Snow World, which is also open at night and which has illuminated full size buildings made from blocks of 2–3ft thick ice taken directly from the Songhua River.
Each year there is a different theme and it always includes the world's biggest ice sculptures.
Saws are used to carve ice into blocks. The ice blocks are mainly taken from the frozen surface of the Songhua River. The artists then use chisels, ice picks and saws to carve out large scaled ice sculptures. However, some sculptors now use deionised water, because this makes ice blocks as transparent as glass.
The cloudiness in natural use is a combination of tiny bits of mud and plant, and also dissolved salts. You get rid of the solid pieces by boiling and then condensing the water (it's called distillation) and you then get rid of the salts by a chemical process called deionisation.
