Why?

[EIRE2003]

In this glaciated upland region why is the the river or lake a green colour? Me thinks that it is obviously to do with the sediment on the bed of the lake. Perhaps it is a chalk bed or a solution lake?

[Nereid]

Where is this?

It may be "rock flour" (http://www.vec.ca/english/4/lake_louise.cfm).

[EIRE2003]

This photograph is taken of the Andes in Argentina.

[Nereid]

This photograph is taken of the Andes in Argentina.
New Zealand also has turquoise glacial lakes (http://www.moxon.net/new_zealand/twizel.html), with "rock flour" ascribed as the cause.

In this image (http://pubs.usgs.gov/prof/p1386i/chile-arg/wet/fig33.html), of some lakes in the Andes, the rock flour is said to cause the lakes to be 'light blue'.

Seems to be variations on a theme. :smile:

[tyroman]

Care must be taken when making assumptions about satellite images, particularly when the words "false color" appear in the caption...

Sensors on landsat type surveyors often detect and record electromagnetic signals which are outside the visible spectrum. To display this information visually in a photograph, scientists assign a false color (in the visible spectrum) to wavelengths otherwise invisible to the human eye. Thus, the color of something in a satellite photo is not necessarily its real color...

[EIRE2003]

Yes i know that but this is not a satellite photo this photo was taken from the ISS. There is no false colour it is a natural.