| Answer | Crossword Clue |
|---|---|
| SST | Former flier at 55,000 feet |
| troposphere | a region of the atmosphere from 25,000 feet to 55,000 feet, the boundary between the upper troposphere and the lower stratosphere |
| tropospheres | TROPOSPHERE, a region of the atmosphere from 25,000 feet to 55,000 feet, the boundary between the upper troposphere and the lower stratosphere |
