Ray was bit short. Rising hot air, spiraling thermals, are needed to lift the glider, allowing for trips up and gliding down and up again. Birds often use these same thermals. Warming air is must.
Thermals are a "must" here in the flatlands, though occasionally there will be a convergence of two air masses blowing against each other causing rising air at the intersection. But that's still more of a daytime occurrence, as normally winds subside after sunset. It happens here when cold air over the Gulf of Mexico moves in under the air over the land, called the Sea Breeze. It is visible when both sides have clouds, but the clouds on one side will be at a distinctly different altitude than the other side of the convergence.
If you have mountains, you can surf the wind rising up the slopes, and, if present, "wave" on the lee side above the peaks, which can take you amazingly high.
I saw a plan by two women to take a two-seater into the air for three days and two nights (nonstop) from Alaska to the Mexican border using "wave" off the mountains along the west coast of the USA and Canada.
They will need lights on the plane, to be seen at night, and Transponder for Air Traffic Control to see them at the expected altitudes (over 18,000 feet), and supplemental oxygen, along with whatever else they ight pack for 3 days.