Originally Posted by bbjsw10
Am I the only one that is laying on his side to watch this?
I wish there was someplace to slope around me, I may need to start watching for some. Should the wind blow at the slope or away? Side of a reservoir work?
Any aircraft that doesn't have a motor will only stay up when it is in rising air, which we call "lift".
One source of lift is ridge lift, or slope lift. It happens when the wind encounters an obstruction, such as a cliff or slope. So yes the wind has to blow against, and up, the slope.
Another source of lift is "thermals". This happens when the air is heated by the sun warmed ground to a temperature that is higher than the surrounding air. It forms a big bubble that breaks loose and rises up through the cooler air. If you live in the flatlands you may have to use thermals. To do that usually requires having your glider towed up by a "High-Start" or a winch. But if your glider is light enough and you're strong enough you can throw it up to thermal catching altitude, about 100' minimum I think.