Hello Raimo
Thank you for your posting on "colour & temp".
I think you are missing vital consideration.
What about a surface that reflects a reasonable amount like like cement
runways and parking areas?
I am a hot air balloonist. My last homebuilt is a huge 8 ball, 95,036
cubic feet (majority is black). When there is good solar energy around, I
can take a person in a harness attached to the envelope and fly them solar
powered. It works far better on a white runway compared to black taxiway.
I attribute this to reflection to lower part of balloon in addition to
direct solar.
I expect reflection from a cement surface can heat lower of Europa less
whenm it is white than dark.
The very best conditions I have had for solar flight was on a frozen lake
covered with snow when it was -20F. This is in part to do with thick air,
but amount of heat generated to dark was very impressive. It was dead calm
and an awful lot of cold clothes came off, and packing away was mini
summertime.
If calm wind and strong sun reflecting off snow, it would be well advised
to measure underside of dark composite, I have feeling it could surprise
you.
Ron Parigoris
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