The other day I learned the different classifications of dawn and dusk.
Your layman may be satisfied with the general “dawn,” “morning,” “evening,” “nighttime,” but for those who need to know exactly what kind of morning is under discussion there are four phases of dawn and dusk, respectively, all with wonderfully exotic, romantic sounding names. In order, from first to last dawn (reverse for dusk), they are Astronomical, Nautical, Civil and Solar.
I won’t bore you with the details as Wikipedia has a wonderfully informative and succinct article on the subject. Suffice to say my favorite two are Nautical and Civil dawn. Except for under ideal circumstances (weather, terrain, etc) the Astronomical flavor of both dawn and dusk are essentially indistinguishable from ordinary morning or nighttime. Meanwhile, there tend to be too many people mucking about to really enjoy nautical or civil dusk.
The nautical and civil dawns represent, for me, the times of day when anything is possible and nobody is watching. The world consists of you, your thoughts and a couple of 24hr Donut shops. Anything can happen next but for those few minutes – they only last a few minutes – it’s just you.