High, dry, and cold, the stratosphere is the layer just above where most weather occurs, extending from about 10 km to 50 km (6 to 31 miles) above Earth’s surface.

Earth's atmosphere is far bigger than we had realised, scientists announce The gaseous layer reaches out far past the Moon Andrew Griffin Friday 22 February 2019 18:08 GMT 0 Comments ...

Earth as oxygenator Earth loses about 90 tons of gas—mainly hydrogen and helium—to space every day. That’s tiny compared to the mass of our atmosphere, so there’s no cause for alarm.

If microbes can grow under Mars-like conditions, which experiments say a few can, then maybe they could live as high as 31 miles in Earth's atmosphere, says an expert.