We just had a regular, screened lanai, when we moved here. When it rained the lanai would always get wet, and we could not use it, whenever it rained. So we had Custom Windows and Exterior Design, enclose our Lanai with sliding glass tinted windows, that slide all the way to one side. Now we can watch the great thunder and lighting shows from our Lanai and it doesn't get soak either, like it used to do.
Here's Custom Windows web site, so you can look at some of their glass enclosed lanais.
Custom Windows R Us – Custom Windows and Exterior Design