I thought it might be useful to highlight some of these links to you, so I will start with a superb set of lecture notes from the University of Indiana, Bloomington by Professor Schieber, on the topic "Earth - Our Habitable Planet". Here is a link to the first part of the series. One of the chapters has been on the links list for some years, but in such a long list it could easily get over-looked. I have re-titled it to give it a more relevant title. There is a lot of material there. It is more like a textbook and should be read in short chunks, but it is mainly easy to read, though some scientific knowledge is useful for a complete understanding.
The next set of lectures cannot be obtained from the link on the website, but I have a link from Professor Schieber and I will be looking at these in a later post, including his notes on the Greenhouse Gases, in which I fear he seems to take the alarmist line. But despite this one disappointment I still believe these are a good set of lecture notes.