A brilliant way to start the day

QUASQUETON - Wednesday's dawn might have made the early settlers around here think the East Prairie was on fire.

Of course, the native vegetation that inspired the still-used East Prairie name has long since been replaced by corn and soybeans. And of course, the red and yellow conflagration that appeared to be licking at the edge of town was nothing more than another spectacular autumn sunrise.

While I watched the TV news around 6:30, the rising sun suddenly bathed the room in brilliant orange, inviting me outside to watch the crescendo through the gnarled, bare branches of the giant Burr Oak overlooking my garden.

As you will recall from your junior high science classes, a phenomenon called Rayleigh scattering accounts for the sky's blue appearance during the day and its warmer colors just after dawn and just before dusk.

As Mr. Helt so patiently explained, the earth's atmosphere, composed mainly of nitrogen and oxygen molecules, scatters the light of the sun differently at different times of the day.

At high noon, when we viewers of the sun's light are as close as we can get to its source, we see only the blue and violet at the short-wave end of the color spectrum. At the day's early and late edges, when the sun's rays travel much farther to reach us, the short waves get too scattered for us to see, leaving only the longer-wave reds, oranges and yellows.

Among Iowa's celestial displays, which include fleeting shooting stars and infrequent northern lights, only a nocturnal thunderstorm can rival the grandeur of an autumn sunrise.

Some people think sunrises and sunsets are more colorful in the fall than at other times of the year. If that's the case in Iowa, one reason might be that the particles of dust dislodged by the harvest of corn and soybeans increase the Rayleigh scattering effect.

While that seems plausible, my preferred theory, with sunrises especially, is that we just see more of them because the sun rises later in the fall, after most of us are already up for the day.

Thursday's sunrise was subtler than its immediate predecessor, with salmon and pink tones confined to a much less expansive corner of the sky, but still worth the moment it took to observe it.

As with the preceding day's fiery extravaganza, it soon flamed out, leaving us sunrise enthusiasts to face a day that was probably not going to get any better than its start.