© Luke Hamill/The OregonianA circumhorizontal arc over Mount St. Helens on Sunday, June 19, 2016.
On Sunday, which happened to be the day of the Pride Parade in Portland, what seemed like a magical rainbow cloud appeared over Mount St. Helens.
According to the Andy Bryant, hydrologist for
the National Weather Service in Portland, it was in fact science, not magic, that painted the sky rainbow colors yesterday.
Also, it wasn't a "rainbow cloud." Instead, it was something called a "
circumhorizontal arc."
Circumhorizontal arcs are caused by a combination of crystals in clouds and the angle of the sun.
Bryant says circumhorizontal arcs are actually not that uncommon in the summer in Oregon. "Sometimes you can get multiple arcs in different positions in the sky," he says, "depending on how much of a cloud layer there is and on the type of ice crystals."
"It's kind of cool stuff," he adds.
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