I previously reported the white-out bug on 2008.Dec.16 saying,
"I was flying at 39,000 asl and the white-out bug returned. This is lower altitude than last seen. I discovered the threshold was changing with sun-angle, so mapped the threshold. It occurs down to 36,400 when sun-angle is 1.56"
A combination of sun-angle and altitude defines the threshold for where this occurs. As the sun-angle decreases, or the sun gets higher in the sky, the altitude at which this occurs gets higher.
Also, at lower altitudes, the problem seems to occur when the sun is on the horizon, perhaps the specular effects at sunrise are the problem? Because continuing into night from day, the white-out disappears at sun-angle 1.65
Here are screenshots from today's flight:
Climbing past 137 thousand feet, sun angle 1.26 looking good
Enter white-out, which is grey this time, near 304 thousand feet, sun angle 1.24
Exit white-out near 1.5 million feet, sun angle 1.22
Change heading and observe brightness of sun. (Too bright)
Rotate viewing angle, includes darker side and cockpit with interior lights on
Nose down, re-enter white out near 1.5 million feet, sun angle 1.18
Descending, exited white-out near 167 thousand feet, sun angle 1.20
Turn west, looking good
Re-enter white-out. This time atmosphere is totally white, as seen before, except cockpit still visible.
Reverse engines to discover sun-angle at 1.46 for altitude 150 thousand feet.
Descending to previously reported altitude, looking good again.
Now at 39 thousand feet. sun-angle increases to 1.54 with moon below horizon, or should be.
and re-enter white-out. This time aircraft surfaces look normal.
Then a second later, the aircraft surfaces show white where sun shines. This can affect any aircraft at 39,000 feet.
Switch view to inside, and observe really interesting, some surfaces are white, others are okay. Especially textured surfaces seem normal.
Ascend to 100 thousand feet, and search for next threshold. Switch livery to texture based to observe difference.
Re-enter white-out at sun-angle 1.49. Notice all diffuse and ambient settings for livery are discarded. The blue hull becomes plain leather-cream.png
Advance time to midnight (sun-angle 2.17 at current latitude) and ascend. Sun is visible as ground disappears.
Looks okay up to 260 thousand feet
Then atmosphere starts dropping away into distance
Understandable, but not correct if long term goals include NASA space shuttle and International Space Station
346 thousand feet. Grey space becomes visible
Looking okay (except no Earth) at 741 thousand feet. Space becomes blacker as altitude increases.
Then becomes grey again. Also changes based on direction of view. (Specular with sun.) Just about to exit white-out (grey at this time of day) at 4.45 million feet
4.48 million feet
Rotate view to show loss of ambient and diffuse colors again
Descend back down to 293 thousand feet with sun-angle closer to dawn to show where atmosphere becomes distant.
Climbing past 137 thousand feet, sun angle 1.26 looking good
Enter white-out, which is grey this time, near 304 thousand feet, sun angle 1.24
Exit white-out near 1.5 million feet, sun angle 1.22
Change heading and observe brightness of sun. (Too bright)
Rotate viewing angle, includes darker side and cockpit with interior lights on
Nose down, re-enter white out near 1.5 million feet, sun angle 1.18
Descending, exited white-out near 167 thousand feet, sun angle 1.20
Turn west, looking good
Re-enter white-out. This time atmosphere is totally white, as seen before, except cockpit still visible.
Reverse engines to discover sun-angle at 1.46 for altitude 150 thousand feet.
Descending to previously reported altitude, looking good again.
Now at 39 thousand feet. sun-angle increases to 1.54 with moon below horizon, or should be.
and re-enter white-out. This time aircraft surfaces look normal.
Then a second later, the aircraft surfaces show white where sun shines. This can affect any aircraft at 39,000 feet.
Switch view to inside, and observe really interesting, some surfaces are white, others are okay. Especially textured surfaces seem normal.
Ascend to 100 thousand feet, and search for next threshold. Switch livery to texture based to observe difference.
Re-enter white-out at sun-angle 1.49. Notice all diffuse and ambient settings for livery are discarded. The blue hull becomes plain leather-cream.png
Advance time to midnight (sun-angle 2.17 at current latitude) and ascend. Sun is visible as ground disappears.
Looks okay up to 260 thousand feet
Then atmosphere starts dropping away into distance
Understandable, but not correct if long term goals include NASA space shuttle and International Space Station
346 thousand feet. Grey space becomes visible
Looking okay (except no Earth) at 741 thousand feet. Space becomes blacker as altitude increases.
Then becomes grey again. Also changes based on direction of view. (Specular with sun.) Just about to exit white-out (grey at this time of day) at 4.45 million feet
4.48 million feet
Rotate view to show loss of ambient and diffuse colors again
Descend back down to 293 thousand feet with sun-angle closer to dawn to show where atmosphere becomes distant.