Though this explains how glass forms, you might still be wondering how this
takes place in nature. Lighting is one way that glass can form in a natural setting.
When a bolt of lightning hits a sandy patch of soil, it can create natural pieces of
glass called fulgurites. This occurs in much the same way as we create glass
synthetically. In this case, though, the bolt of lightning creates the extreme heat
needed to form glass.
According to the passage the word synthetically means