Drought and air pollution aren’t all bad.
Along with this winter’s dry, warmer-than-normal weather, Bay Area residents are experiencing some of the most spectacular sunrises and sunsets in recent memory.
The lack of rain and wind, scientists say, is producing picturesque horizons as a result of increased pollution particles trapped in the sky. The “particulates” scatter light and create the eye-catching colors that have prompted oohs and ahhs across the Bay Area and countless clicks of smartphones aimed at dramatic skies — from fiery sunrises above the Aeolian Yacht Club off Alameda’s Bay Farm Island bridge to breathtaking Pacific Ocean sunsets up and down the coast.
From her ocean perch on West Cliff Drive in Santa Cruz, Karin Carter, a businesswoman and amateur photographer, snapped away last week at what she described as “fantastic formations of clouds … big and bold in the sky, lighted up with pinks, oranges and reds.”
At San Francisco’s Ocean Beach, Kevin Yang, a marketing professional from Cupertino, recently joined dozens of beachgoers to click away at a pink sky more glorious than anything he’d seen before.
“People were in awe,” he said. “No one was talking. Everyone was quiet and just enjoying the moment and the colors.”
It doesn’t hurt either to be enjoying such vivid sunsets in record high temperatures that are also defining January in the Bay Area. On Wednesday, 11 spots in the region broke records, including Santa Cruz’s 82 degrees, Salinas’ 85 and Oakland’s 76 — the East Bay city’s fifth record this month. San Francisco International Airport marked its hottest January day — 73 — since it started recording temperatures in 1927.
Stop-and-stare sunsets like these are more common during the winter and will continue to marvel for the next few weeks, weather forecasters say. That’s because weather patterns cause more particles to sweep over the lower atmosphere and disperse light. And when it’s a winter devoid of precipitation and wind like this year, tiny particles of soot and dust from cars, fireplaces and construction work stick around much longer — which leads to even more dazzling light shows.
“If you think of visible light as blue, green and red, pollution particles often scatter out the blue and the green and transmit the red,” said Mark Jacobson, director of Stanford’s atmosphere and energy program. “The red gets bounced around, creating this red horizon.”
Light from the sun travels farthest through the lower atmosphere during sunset and sunrise than at any other time of the day. The particles in the atmosphere disperse shorter wavelengths like blue, violet and green in many different directions. But longer red, orange and yellow wavelengths stand a much better chance of making it through the particulate gantlet and into our lucky eyes.
Alison Bridger, chairwoman of the meteorology department at San Jose State, said the underlying reason for the lack of rain and resulting air pollution is the stubborn high-pressure ridge parked off the West Coast. Another factor contributing to the increased pollutants is a phenomenon known as offshore flows, said Patrick Chuang, professor of earth and planetary sciences at UC Santa Cruz. Offshore flows happen throughout the winter, reversing normal wind patterns that typically blow clean air inland from over the Pacific Ocean.
Moreover, the air pollution is being exacerbated by an atmospheric inversion that occurs at night, said Jan Null, a meteorologist with Golden Gate Weather Services in Saratoga.
Normally the air gets colder and colder the farther up into the atmosphere it goes, but during an inversion a level of warm air rises above a level of colder air and traps the cold air near the ground, closer to the horizon. When that cold air contains a lot of particulates and other aerosols, he said, the contaminants start building up.
“The bottom line,” Null said, “is take pictures — but don’t breathe.”
