Images
November 18, 2024 - Two Views of Fog in Scandinavia
True Color Image
False Color Image
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A dense bank of fog surrounded the Scandinavian Peninsula on November 8, 2024, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the region. The fog blanketed most of southern Sweden, crept into the valleys of the Scandinavian Mountains, and also covered the western coast of Denmark. At the same time, snow covered the high elevations in the mountains. The snow and fog created a scene dominated by white.
In this true-color image, snow and fog both look white and are somewhat difficult to distinguish with certainty. The biggest clue used to separate snow and fog is that snow tends to be much brighter white than fog. Fog, which is a type of low-lying cloud, is less reflective so it typically looks softer and a little darker than snow. Often, however, fog and snow look alike enough that telling them apart involves some guesswork in true-color images.
In order to more accurately tell where fog stops and snow dominates, scientists often turn to false-color images. The difference between false-color and true-color images is simply the MODIS bands used in compiling the images. True-color images use data from bands 4,3, and 1 to create an image that appears very much like the human eye would see the scene. The use of data from MODIS bands 7,2, and 1 result in an image that looks very different than the way we see the world, but one that shows a true difference between snow and cloud.
Our Image of the Day today compares the true-color image from November 8 with the same image processed as a false-color image using bands 7,2,1. Clicking on the titles below the image will allow an easy comparison between true-color and false-color images of this scene.
In the false-color image, water shows up as dark blue, vegetation looks dark green, and ice or snow appears a bright electric blue. In this type of image, clouds—especially fog—usually looks white, However, cold clouds contain ice crystals, and the presence of ice will give the cloud a tint of bright electric blue. Very high, cold clouds can look significantly blue, but rarely would even the coldest cloud show the intense color saturation of snow.
Image Facts
Satellite:
Terra
Date Acquired: 11/8/2024
Resolutions:
1km ( B), 500m ( B), 250m (4.2 MB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
True Color Image False Color Image
A dense bank of fog surrounded the Scandinavian Peninsula on November 8, 2024, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this true-color image of the region. The fog blanketed most of southern Sweden, crept into the valleys of the Scandinavian Mountains, and also covered the western coast of Denmark. At the same time, snow covered the high elevations in the mountains. The snow and fog created a scene dominated by white.
In this true-color image, snow and fog both look white and are somewhat difficult to distinguish with certainty. The biggest clue used to separate snow and fog is that snow tends to be much brighter white than fog. Fog, which is a type of low-lying cloud, is less reflective so it typically looks softer and a little darker than snow. Often, however, fog and snow look alike enough that telling them apart involves some guesswork in true-color images.
In order to more accurately tell where fog stops and snow dominates, scientists often turn to false-color images. The difference between false-color and true-color images is simply the MODIS bands used in compiling the images. True-color images use data from bands 4,3, and 1 to create an image that appears very much like the human eye would see the scene. The use of data from MODIS bands 7,2, and 1 result in an image that looks very different than the way we see the world, but one that shows a true difference between snow and cloud.
Our Image of the Day today compares the true-color image from November 8 with the same image processed as a false-color image using bands 7,2,1. Clicking on the titles below the image will allow an easy comparison between true-color and false-color images of this scene.
In the false-color image, water shows up as dark blue, vegetation looks dark green, and ice or snow appears a bright electric blue. In this type of image, clouds—especially fog—usually looks white, However, cold clouds contain ice crystals, and the presence of ice will give the cloud a tint of bright electric blue. Very high, cold clouds can look significantly blue, but rarely would even the coldest cloud show the intense color saturation of snow.
Image Facts
Satellite:
Terra
Date Acquired: 11/8/2024
Resolutions:
1km ( B), 500m ( B), 250m (4.2 MB)
Bands Used: 1,4,3
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
