why is the blue lake blue in mt gambier
Blue Lake (South Australia) During December to March, the lake turns to a vibrant cobalt blue colour, returning to a colder steel grey colour for April to November. The exact cause of this phenomenon is still a matter of conjecture, but it is generally considered likely that it revolves around the warming of the surface layers of the lake during the summer months to around 20 °C (68 °F), causing calcium carbonate to precipitate out of the solution and enabling micro-crystallites of calcium carbonate to form. This results in scatter of the blue wavelengths of sunlight. During winter the lake becomes well mixed, and recent research indicates that during this phase of the colour cycle the lake is somewhat murkier due to the redistribution of tannins and calcium carbonate particles throughout the lake. Solar elevation has also been found to influence the perceived colour of the lake. The movement of planktonic life-forms within the lake during the seasons and during the day may additionally play a part in the colour change.
Blue Mountains (New South Wales) Following European settlement of the Sydney area, the area was named the Carmarthen and Lansdowne Hills by Arthur Phillip in 1788. The Carmarthen Hills were in the north of the region and the Lansdowne Hills were in the south. The name Blue Mountains, however, was preferred[8] and is derived from the blue tinge the range takes on when viewed from a distance. The tinge is believed to be caused by Mie scattering which occurs when incoming light with shorter wavelengths is preferentially scattered by particles within the atmosphere creating a blue-greyish colour to any distant objects, including mountains and clouds. Volatile terpenoids emitted in large quantities by the abundant eucalyptus trees in the Blue Mountains may cause Mie scattering and thus the blue haze for which the mountains were named.[9]