How do sailplanes (gliders) stay aloft?
Gliders are usually towed to altitude by a motorized airplane and then use rising air from natural weather phenomenas such as thermals, mountain lee waves or ridge lift to stay aloft.
### Instruction: How do sailplanes (gliders) stay aloft?
### Context: 
### Answer: Gliders are usually towed to altitude by a motorized airplane and then use rising air from natural weather phenomenas such as thermals, mountain lee waves or ridge lift to stay aloft.</s>