Timeline for Why are the clouds white and Australia black in weather satellite infrared images?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 18, 2020 at 16:21 | comment | added | David Hammen | The image shown in the question is a gray scale image, so this isn't quite pseudo color or false color. It's a negative. | |
| Feb 17, 2020 at 14:07 | comment | added | gerrit♦ | @Jean-MariePrival Sure. I don't know if there is a scientific definition of false color. Either RGB's (putting three satellite bands or band differences in the R, G, B, channels respectively regardless of actual wavelength) or applying colormaps to single-channel images is commonly done. At least in satellite meteorology, it's unusual to call them false color images. | |
| Feb 17, 2020 at 14:02 | comment | added | Jean-Marie Prival | @gerrit I was thinking of images like this: en.wikipedia.org/wiki/False_color#/media/… Apparently they are computed from the grayscale images, and there are lots of different algorithms, meaning that a given shade of yellow (or red...) does not always represent the same temperature: diva-portal.org/smash/get/diva2:797457/FULLTEXT01.pdf | |
| Feb 17, 2020 at 13:30 | comment | added | gerrit♦ | I can confirm that these conventions were chosen because meteorologists looking at the pictures want that clouds look white, regardless of channel (source: personal communication with forecasters). I'm not sure if representing a single channel as a greyscale image is technically pseudo-color. By that reasoning any narrowband greyscale image would be pseudo-color, even if taken in the visible range, wouldn't it? | |
| Feb 17, 2020 at 13:14 | comment | added | uhoh | Thank you for your speedy answer! I'm not thinking of temperature necessarily, I'm just thinking that satellite images for the 0.4 to 0.7 micron band show higher intensity as lighter, as do thermal IR cameras, so Himawari-8's IR1 (channel 13) at 10.4 microns would as well. Maybe the inversion making the clouds white just makes them more intuitive. | |
| Feb 17, 2020 at 13:02 | history | answered | Jean-Marie Prival | CC BY-SA 4.0 |
