Valentine’s Day Sunrise Surprise

Inversion layers in lower atmosphere distort the sun into fantastical shapes at sunrise this morning (Feb. 14) over Lake Superior in Duluth. Bob King

Before I gave my wife a Valentine’s Day card and gift, even before she awoke, I got up and drove to a clear spot to watch and photograph the sunrise. Along the way, my heart sank when I saw that low clouds and haze muddied the horizon. I almost turned back.

Despite the mistiness, the sun appeared right on time though only a moment later it lost its top! A thin layer peeled off and evaporated into thin air. Several other slices did the same, but of course the sun held together through those atmospheric indignities. For a time, layers of stratified air created a series of notches or steps on either side of the solar disk.

The photos show these layers, each one unique with a different temperature and density and stacked one atop the other noodles in a tasty lasagna. The sun’s appearance changed almost second by second as it ascended through the stack until it finally climbed high enough to settle down and round out.

How far one away you can see to the horizon depends upon your elevation. I stood about 400 feet above the level of Lake Superior and the Wisconsin shoreline. At that elevation the horizon — where the sun rose — was about 24 miles away. That means these photos sample at least 24 miles (39 km) of the lower atmosphere.

A slice of sunlight hovers briefly over the sun before disappearing about a minute after sunrise this morning. Bob King

Because we’re looking through the atmosphere at a very shallow angle and the morning was calm, the air settled into layers according to temperature. Normally, air near the ground is warmer than air above, but when warm fronts move across cold, snowy lands, the reverse can happen. Cold air settles at the ground with warm air above, creating an inversion layer. Sometimes there are multiple inversion layers as there were this morning, and the sun looks like a Whoville layer cake.

These layers are normally invisible, but when the sun works its way through them while rising or setting, the distortions they introduce in its perfect disk give them away.

In this close up view, stratified layers of air seem to slice of pieces of the sun shortly after sunrise today. Bob King

Every sunrise is different. The more of them you see, the more you learn and the deeper your appreciation of nature. Next time, I won’t even consider hesitating as I embark on that next sunrise adventure.

Still looking for the right Valentine? Feel free to use this one from the OSIRIS-REx mission courtesy of NASA