- #1
What Causes Rivers and Lakes to Appear Green in Glaciated Upland Regions?
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Discussion Overview
The discussion revolves around the reasons for the green color observed in rivers and lakes located in glaciated upland regions, with a focus on specific examples from the Andes in Argentina and New Zealand. Participants explore various hypotheses related to sediment composition and the effects of glacial activity.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant suggests that the green color may be due to sediment on the lake bed, possibly chalk or a solution lake.
- Another participant mentions the presence of "rock flour" in New Zealand's turquoise glacial lakes as a potential cause for similar coloration.
- There is a discussion about the interpretation of satellite images, with one participant cautioning against assumptions related to "false color" in such images.
- A later reply clarifies that the photograph in question was taken from the ISS and asserts that it is a natural color image, not a satellite photo.
Areas of Agreement / Disagreement
Participants express differing views on the causes of the coloration, with some proposing sediment-related explanations and others discussing the implications of image interpretation. The discussion remains unresolved regarding the definitive cause of the green color.
Contextual Notes
Participants highlight the importance of understanding the context of images, particularly regarding color representation in satellite versus natural photographs. There is an acknowledgment of the complexity involved in interpreting these visual data.
- #2
Nereid
Staff Emeritus
Science Advisor
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Where is this?
It may be http://www.vec.ca/english/4/lake_louise.cfm .
It may be http://www.vec.ca/english/4/lake_louise.cfm .
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- #3
EIRE2003
- 107
- 0
This photograph is taken of the Andes in Argentina.
- #4
Nereid
Staff Emeritus
Science Advisor
Gold Member
- 3,397
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New Zealand also has turquoise glacial lakes, with "rock flour" ascribed as the cause.EIRE2003 said:
In this image, 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.
- #5
tyroman
- 139
- 0
To EIRE2003
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...
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...
- #6
EIRE2003
- 107
- 0
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.
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