Twilight Sky 9:47 P.M.

It is only because there are prominent clouds that it appears dark at this time of night. We are near summer solstice here, the longest day of the year. It doesn't really get darkish this time of year until about 1:00 A.M.

I am riding out to Nancy Lake. There are pockets of rain here and there. I am watching the clouds for more rain. I wonder how thick is the survivable airspace above us?

I know at as low as 10,000 feet people that are not acclimated can suffer and die from altitude sickness. Loss of consciousness occurs in only minutes at 25,000 feet, and it is only about -40 to -60 degrees Celsius at that altitude.

25,000 feet, that's less than 5 miles. I have traveled 40 miles from Anchorage. At 60 miles per hour I travel the height of livable airspace in 5 minutes. I can see across the Hay Flats for about 8 miles, i.e. I can see farther than there is height of livable atmosphere! We, and the Earth, are surrounded by only a thin vapor of air giving life.

Think about this the next time you gaze across a field or plain. Look across the distance, then look up. There is less livable airspace up there than from you to the horizon!