Field Notes—

The Blue Hour

By Curtiss Clark

The rise and fall of our planet’s tilting waltz around the sun moved the angle of our inclination to our favorite star across the equator to northern latitudes last month. This was just after we engaged in our semiannual compulsion to tinker with time. The vernal equinox and the return of Daylight Saving Time combined to flood the early evening hours with light. The evening daylight, of course, is not saved at all; it is simply stolen from the morning.

After struggling for months to free ourselves from the folds of winter’s dark cloak, we were finally getting up with the sun in late February and early March, until, that is, the recoil of the great spring spring-ahead kicked us early risers back into the blue hour.

The blue hour is what the French call that twilight time between the total darkness of night and sunrise when light has a quality dissociated from both day and night — not black, not white, but blue. The implication is that being discrete, apart from the normal cycle of hours, this time is special — auspicious, even.

Leave it to the French to choose impressionism over empiricism. Contrast l’heure blue with how the National Oceanic and Atmospheric Administration defines three distinct types of dawn:

Astronomical dawn — the moment when the sun is 18 degrees below the horizon and the sky is no longer completely dark.

Nautical dawn — the moment when the sun is 12 degrees below the horizon and there is enough light for some objects to be distinguishable.

Civil dawn — the moment when the sun is six degrees below the horizon, and there is enough light for objects to be distinguishable so that outdoor activities can commence.

I’m with the French on this one. I have no idea how to tell whether the sun is 6, 12, or 18 degrees below the horizon because… well, it is below the horizon and I can’t see it. The blue hour blesses the wakeful with attenuated senses, finely calibrated to the subtle shift of night toward day. If there were a time when we could see around corners, this would be it.

When the first least waves of light and their attendant warmth stir still-chilled pools of air to rising, the pressure beneath that ascension drops like an eddy, sucking something less than a zephyr a few feet or a few yards across the ground, or a branch, or the neck nape of a titmouse, sparking the only real thought a titmouse has this time of year: sex. And because of the urgency of this thought, the titmouse decides it is time for outdoor activities to begin, regardless of the precise position of the sun.

So it is that I am bound to awaken in the blue hour these days to three sharp whistles, and then two, and then more variations on this insistent titmouse theme, which demands an acknowledgment and, with luck, some lady’s admiration. The response comes in time in a lilting libidinous chorus of birds of every kind — paean to the welcome heat of another auspicious day. Everybody rise for the waltz’s promenade.

(This and more than 60 other “Field Notes” essays are available at www.field-notebook.com.)