New tool for generating colored sky

We provide a new tool in frads, called gencolorsky, that enables you to generate a color sky description using libRadtran. You’ll need to install libRadtran first in order to use this tool. You’ll need to also install the supplemental Optical Properties for Aerosol and Clouds (OPAC) data if you want to use the standard aerosol profile demonstrated below. After installing libRadtran, you can simply run pip install -U frads to install frads, and gencolorsky will be available to you in command-line. Refer to documentation here for more details.

Here are some sample inputs/outputs from gencolorsky (human adaptation filter applied):

Mid-latitude summer, 12:00, cloud cover = 0, aerosol = continental clean.
gencolorsky 2022 06 21 11 0 -a 37.7 -o 122.2 -m 120 -l continental_average

Mid-latitude summer, 12:00, cloud cover = 0, aerosol = continental polluted.
gencolorsky 2022 6 21 12 0 -a 37.7 -o 122.2 -m 120 -l continental_polluted

Mid-latitude winter, 11:00, cloud cover = 0, desert aerosol profile at 2km altitude
gencolorsky 2022 12 21 11 0 -a 36 -o 106 -m 105 -u 2 -l desert

Mid-latitude summer, 18:30, cloud cover = 0.2, aerosol = continental_average
gencolorsky 2022 6 21 18 30 -a 37.7 -o 122.2 -m 120 -l continental_average -b .2

Mid-latitude summer, 18:30, cloud cover = 0.2, aerosol = continental_average, output in photopic (CIE-Y), melanopic(EDI), and solar for each of the three-channel.
gencolorsky 2022 6 21 18 30 -a 37.7 -o 122.2 -m 120 -l continental_average -b .2 -i

8 Likes

Hi Taoning,

this is very exciting news! Is libRadtran available for Windows users? Unfortunately, I did not find much about this on libRadtran website. There is a Readme.windows document among downloaded files which recommends tools to install the libRadtran C and Fortran libraries under Windows 95/98/NT/2000. Is this still valid or rather outdated?

Best,
Rita

Hi Rita,

Thanks for the enthusiasm. I’ve not tried to compile it under Windows. It’s probably worth a try? I imagine it’ll be difficult though.
LibRadtran website does seem to suggest compiling and using it under the Windows Linux subsystem. It’s viable but not ideal if you do the rest of your work under regular Windows.

For anyone else revisiting this post 10 years later …

Mark J Stock also made a colored sky in 2009 which includes starts (why not!?)

See more here

http://markjstock.org/radiance/radiance_harvard_09_stock.pdf