I have visited areas with glacial lakes, but I have not investigated the reasons for the different colours. Glacial flour refers to the component of glacial sediment that is much finer than sand. In the warmer months, especially spring and summer, the glacial flour or rock flour created by glacial erosion enters the glacier’s meltwater stream along with various other debris. The fine particles of pulverised rock absorb and scatter sunlight in a way that can give the water a striking blue-green colour.
So glacier flour is the magic ingredient that gives glacier waters that bright turquoise hue. However, the glacial flour is found in the water column and is the reason for the cloudy appearance of glacial waters.
Is glacier water blue?
Lakes with the smallest rock flour particles have a more brilliant blue colour than lakes with larger rock flour suspensions because they reflect light differently. Although some people claim that the turquoise colour of the glacial lake is due to the reflection of sky blue by the water surface, this is not correct. Fascinated by the blue-green water, he later reported: “In all my explorations, I have never seen such an incomparable scene. To every successful recipe belongs the right mixture, and so it is with the mystery of why the glacier water is blue.
So if there is no other pigment near the surface of the water, such as green algae or plankton, it will always appear blue or slightly blue-green.
What gives glacial lakes their colour?
This was very interesting, and I have to admit that I didn’t know why the lakes were such a spectacular turquoise blue. As a neighbour in the province (I live on Vancouver Island), Lake Louise is one of my absolute favourite places. You can only get there by taking a boat tour offered on the lake shore, or by spending a long day canoeing or kayaking yourself. The more of this glacial milk mixture there is, the more turquoise it appears to the amazed observer.
When the fine particles mix with the ice-cold glacier water, more shades of green and blue are reflected, making the water appear turquoise. Glacial flour, also known as rock flour or glacial silt, is a sediment of ground-up rock and gravel particles produced during glacial erosion.
Why are glacial lakes so clear?
They were originally a series of lakes that became one of the largest lakes in Banff National Park when the water level was raised by dams. Meltwater from the glacier slowly filled the holes or spaces created by the moving glacier and formed a lake. From Lake Louise in Canada’s Banff National Park to Lake Tekapo in New Zealand, all of these incredibly blue bodies of water have in common their proximity to glaciers. This, combined with the current retreat of glaciers due to climate change, has led to a shift from frozen to liquid water, increasing the extent and volume of glacial lakes around the world.