Red Sky at Night

This time of year, we catch the sunrise while doing morning chores and the sunset during afternoon chores. It’s a bit like having a pair of bucolic bookends at either end of our day.

The adage “red sky at night sailor’s delight, red sky in the morning sailors take warning,” often comes to mind. The original version of that saying refers to shepherds not sailors. “Red sky at night shepherd’s delight, red sky in the morning shepherds take warning”

During the day, the sun’s rays, which include all the colors of the rainbow, make their best effort to penetrate the earth’s atmosphere. The blue colored rays have shorter wavelengths and are easily reflected and deflected. Like a distracted toddler, they spend the entire day bouncing off various particles in our atmosphere, and never seem to make it to the ground. That’s why, when we look up at the sky, we see mostly blue.

But when the sun is on the horizon, its rays need to pass through even more of the earth’s atmosphere to get to us, and that extra distance reflects and deflects even more of the color spectrum. The reds, yellows and orange colors have the longest wavelengths and are ultimately better able to go the distance. That’s why those colors tend to be more pronounced when the sun is on either horizon.

Depending on the pressure system on the horizon, and its density, additional colors get filtered out.

Low pressure systems, even though they bring more wind and rain, have less dust and soot particles so they let more colors through. The combination of those colors leaves the sky a peaceful yellow color at either sunrise or sunset.

Alternatively, a high-pressure system carries less moisture but more dust, soot and particulates which filter out everything except the red wavelengths and the horizon will indeed appear red.

Since most of our weather comes from the west, if we see a red sky to the west (at night), it means a high-pressure system (bringing good weather) is about to arrive. Whereas a red sky to the east (in the morning) means the good weather has already passed and a rainy low-pressure system is sure to follow.

I have a weather app on my phone, and I monitor it several times a day. It helps us track storms and gives us plenty of time to plan. It allows us to move animals to shelter before the storm arrives – instead of trying to move them in the middle of a blizzard, or torrential rain. My smart phone is a wonderful tool, for which I will be forever grateful - but it has never inspired the kind of awe, or joy, I feel watching the sun go down. Quietly disappearing below a crimson horizon, it leaves me with the promise that “tomorrow, will be another fine day”. Shepherd’s delight, indeed.