Red rainbow weather phenomenon spotted in Massachusetts
After the storms last week, a rainbow came out in central Massachusetts — a red one. “I was just heading to my basketball league that I play in on Tuesday and Thursdays down in Marlboro,” said resident Carter Roy. “And obviously the storms went by us, so it’s pretty crazy out. And then I happened to notice, like, a rainbow that was starting to form.” The rainbow went from one end to completing a whole arc across the sky in “a really tight window,” Roy said. Then as quickly as it formed the rainbow did something rarer — it turned a bright red. “All of a sudden it went from daytime to night,” said Roy. “It was right around dusk, and the sunset was behind me, which is why I think the lighting was so crazy.” Roy was in exactly the right time and situation to see a relatively scarce weather phenomenon, called a red rainbow or monochrome rainbow. The lucky sights occur as rainbow arcs with only red, orange and pink type of hues, rather than the full spectrum of color typically on display. “A rainbow happens when sunlight gets refracted through small water droplets,” said Michael Person, director of the MIT Wallace Astrophysical Observatory and senior lecturer in Earth, Atmospheric and Planetary Sciences. “And as the light is passing through the water droplets, it gets spread out into its colors.” The light get refracted at a particular angle, creating the arc shape with colors spreading from red to violet, Person said. The rainbow appears opposite the sun at an “anti-solar point.” For a rainbow to appear in the monochrome red shade, a few things need to happen. “It happens at very low altitude, just above the horizon when the sun is very close to rising or setting,” said Person. “As the sun rises and sets, the sky gets very red, a traditional sunset. Well, the same thing happens to the rainbow.” All of the colors except for red are “blocked out by the thick atmosphere,” Person explained. The effect always occur when the sun is low, he said, so the rainbow appears to be low on the horizon opposite. Rainbows don’t appear in other monochrome shades, Person said, explaining that to get a green rainbow, something would have to “scatter away everything but green, and we don’t really have that in our atmosphere.” Related Articles Fourth of July expected to be sunny, ‘pretty comfortable day’ in Massachusetts Rising summer heat increases risk of child deaths in hot cars Hurricane Flossie could become a major hurricane off the Pacific coast of Mexico Fingers crossed: 4th of July and Saturday in Boston might actually be rain-free The government cuts key data used in hurricane forecasting, and experts sound an alarm The red rainbows are most sighted in this time of year in the late spring to early summer, in times when there are lots of storms and rain passing quickly, enough water droplets in the air, and enough clarity for sunlight to get through, Person said. “I wouldn’t call the red rainbow rare,” Person said, “but you do have to be lucky, in that you have to have the conditions both for a rainbow and a clear sky on both sides, both where the sun is and where you’re looking, and enough water droplets in the air to make the effect happen in the first place.”
