If you simulate a platform looking down from a 100 km and a 700 km altitude, you should get the same amount of atmospheric contribution because at 100 km you are essentially above all of the atmosphere. This used to work just fine, but it is clearing not working right now.
This one was reported and demonstrated by Mike Gartley.
The problem appears to be related to the change in the sky sphere size and origin made a little while back. The compensation to the path length in the ADB reader no longer worked as expected with the new sky sphere configuration.
A patch was checked in and I am just waiting for Mike Gartley to independently bless the fix.