Probably more so than in any of the other definition discussions we have had up to this point, it is when dealing with exterior lighting that we really need to stress the importance (to the success of the project) of careful observation and reference gathering.

Unfortunately, due to our familiarity with the subject matter, we may be tempted to try and recreate exterior lighting conditions based on memory alone. This can lead us into the trap of thinking that exterior daylight has only a handful of stereotypical scenarios with which we will need to work. Bright and sunny, cloudy and overcast, and where I come from, wet and windy would possibly be three fairly generic descriptions of outdoor weather conditions that we may generate in our mind's eye, especially so if we have not gotten into the habit of closely observing and documenting what is really going on in the world around us.

Of course, these generalizations don't really come close to giving us an accurate description...