Amazing Sunsets and Sunrises to Start Off The Week

Sunrise looking SE over Lake Washington from Seattle

Sunset looking W over Clayoquot Sound from Tofino, B.C.

In the Pacific Northwest, spectacular sunsets and sunrises are the norm. Some of the most amazing sunsets I have ever seen in my life have occurred while fishing off the coast of Vancouver Island, and some of the most amazing sunrises I’ve seen have occurred right from my house, looking south towards Mt. Rainier. Still, some of our recent sunsets and sunrises have been exceptional even for our region.

There are many factors that go into a spectacular sunrise or sunset. You need to have a few clouds of a particular type, you need to have a clean lower atmosphere, and of course, you need to have a clear view of the horizon. Before we go into this particular sunrise and sunset, let’s get a brief primer on why the color of the sky changes at sunset and why some sunrises and sunsets are absolutely breathtaking, while others are mediocre at best.

Since the beginning of time, humankind has wondered why the sky is blue. The reason is because as visible radiation from the sun enters the atmosphere, shorter wavelengths such as blue and violet are preferentially “scattered” throughout the atmosphere by various molecules in the atmosphere, most notable oxygen (O₂) and nitrogen (N₂). This phenomenon is known as Rayleigh Scattering and was discovered by Lord Rayleigh, an English physicist named after Lord Rayleigh, an English physicist who primarily studied acoustic waves (but still managed to pick up a Nobel Prize for co-discovering argon).  Because these wavelengths in particular are scattered throughout the atmosphere, our atmosphere takes on the color of the type of light scattered. It would seem like the atmosphere should appear violet and not blue to us because of this since violet light has even shorter wavelengths than blue light, but our eyes are more sensitive to blue light, so it appears to be the dominant pigment.

As you can see in the above diagram, red, orange, yellow, and green are not scattered, at least to a significant degree. Thus, the sky is blue.

But things change a bit when the sun is low in the horizon, as it is during sunrise and sunset.  When the sun is low in the horizon, sunlight has to travel a further distance through the atmosphere before it reaches its destination. Therefore, it encounters more of those oxygen and nitrogen molecules, and more blue light is scattered. However, this additional scattering doesn’t make the sky even more blue. Instead, blue light is “scattered out” because it interacts with so many molecules that it has trouble reaching the surface. Therefore, we see the longer wavelengths; the characteristic yellows, oranges, and reds, as they have been scattered enough to be visible to us from above, and this light from above can still reach the surface.

We’ve established why the sky turns red at at dawn and dusk. But why are some sunrises and sunsets jaw-droppingly beautiful, while others are simply “meh”? There are a myriad of factors that determine whether a given sunrise or sunset will be spectacular or not, but I’ll go over two basic ones here: air pollution and clouds.

Air Pollution

Contrary to popular belief, air pollution is bad if you are looking for a spectacular sunrise or sunset. Air pollution decreases visibility by a phenomenon known as “mie scattering,” where sunlight is scattered by much larger atmospheric aerosols such as salt, smoke, pollen, and dust instead of air molecules. While Rayleigh scattering from individual molecules turns the sky a deep blue during the day and brilliant array of yellows, oranges, and reds when the sun is near the horizon, mie scattering simply produces a white haze that obscures visibility, making for lackluster sunsets.

The exception to this rule is when we have tons of small particles in the stratosphere, which can make for spectacular sunsets. These sunsets are particularly common after major volcanic eruptions, which release tons of microscopic ash particles and sulfur dioxide into the stratosphere. The sulfur dioxide reacts to make sulfate aerosols, and both the volcanic ash and these sulfate aerosols can create spectacular sunrises and sunsets around the world for months on end. The last eruption big enough to do this was the eruption of Mt. Pinatubo back in 1991. The ash and sulfate aerosols from Mt. St. Helens did not get high enough in the atmosphere to significantly affect sunsets around the world for an extended period of time.

I don’t know about you, but I’ll choose volcanic twilight any day of the week.

Clouds

We need clouds! Clouds help reflect the brilliant reds, oranges, and yellows back to Earth so that we can see them. However, not all types of clouds are great for sunsets. Obviously, if you are experiencing steady, heavy rain falling from a thick nimbostratus cloud associated with one of our typical wintertime atmospheric rivers, you won’t see any sunset at all. But some clouds are truly fantastic for sunsets.

The best clouds with the most clear and vibrant colors are high in the atmosphere, where there are fewer atmospheric aerosols and thus less mie scattering and better visibility. Cirrus clouds, thin, wispy clouds composed of ice crystals several miles high in the atmosphere, are one such cloud. Check out this picture that fellow weather aficionado Brie Hawkins of Little Bear Creek Weather and JB Hawkins Photography took on Sunday night looking at White Chuck Ridge, just to the east of Darrington.

See how the cirrus clouds do an excellent job of reflecting the orange, red, and magenta hues resulting from Raleigh Scattering back down to Earth? This has to be one of the most amazing sunset pictures I’ve ever seen. It looks like a Bob Ross painting!

Here’s another one Brie took Sunday night near the same location a bit later.

The folks at the Seattle National Weather Service took some fine shots as well last night from their office on the shores of Lake Washington.

Monday morning’s sunrise was spectacular as well, but instead of featuring cirrus clouds, it featured altocumulus clouds, which are like the typical cotton-ball cumulus clouds we see but are higher up in the atmosphere. These specific clouds were known as altocumulus castellanus, and often indicate instability in the atmosphere. Indeed, a few isolated thunderstorms developed over the Cascades yesterday.

These clouds are high enough to escape obfuscation from mie scattering in the lowest parts of the atmosphere, but they are generally 6,000 to 20,000 feet up, which is a bit lower than cirrus clouds. Additionally, they are made of water droplets, not ice crystals, and have a more opaque, textured appearance. Their rough surfaces made for an extraordinary sunrise to kick off the work week. The pictures below are also from the Seattle NWS. They sure take some great pictures! Be sure to like their Facebook page for lots more.

Yesterday’s sunset did not have as many clouds, but it was still beautiful in its own way. Here’s yet another picture from the Seattle NWS. Maybe it’s just me, but it just seems like it must have been really hot when this picture was taken. The sky just has that type of color. No blue whatsoever!

I was worried that today’s sunrise would be obscured by a marine layer of stratus clouds, but amazingly, the clouds held off right until sunrise, making for yet another spectacular start to our day. Picture credit: Seattle NWS.

One thing that makes our sunrises and sunsets so great this time of year in particular is that they can last forever. Brie told me that she saw an orange glow in the north until 11:30 pm while shooting her sunset photos on Sunday.

Although there are not many clouds in the sky right now, the visibility is fantastic, and I’m sure tonight’s sunset will be nothing to sneeze at. We are expecting another marine layer to make its way eastward overnight, but if it holds off reaching Seattle until sunrise, we could have another spectacular start to the day.

Happy viewing! We sure do live in a beautiful world.

Charlie