If you’ve noticed some strange blue clouds in the night sky recently, you’re not alone. Uncharacteristically blue nighttime clouds, usually seen over polar regions, have been visible as far south as Colorado and Northern California in recent years.
The clouds, known as “noctilucent clouds” or NLCs, glow blue at night because tiny ice crystals 50 miles (80 km) above the earth are reflecting sunlight from the other side of the planet, according to SFGate. And some scientists say the glowing blue clouds may be yet another effect of climate change.
The vast majority of scientists agree that climate change is real, but NLCs are a good example of how sometimes the secondary effects of climate change may not yet be completely understood. It’s not clear exactly what the glowing clouds have to do with a changing climate, though there are some theories being discussed. One is that methane emissions can create water droplets at high altitudes, which can lead to NLCs, SpaceWeather.com’s Tony Phillips told SFGate. Another idea is that as the Earth’s surface is heating up, the higher layers of the atmosphere (like the mesosphere, where NLCs form) are actually getting colder, allowing the tiny ice crystals for form, University of Colorado Professor Gary Thomas told NASA in 2003.
So if you see blue clouds glowing at night, it may be yet another effect of climate change.
See How California Is Using Its Diminishing Water Resources
The Los Angeles Aqueduct Cascades, which bring water 223 miles from the Owens River in the eastern Sierra Nevada mountains, and 137 miles from the Haiwee Reservoir, are a major source of water for Los Angeles. Seen here in Sylmar, Calif. on May 4, 2015. Lucy Nicholson—ReutersThe Los Angeles Aqueduct Cascades are seen in Sylmar, Calif. on May 4, 2015. California's snowpack, which generally provides about a third of the state's water, is at its lowest level on record. Lucy Nicholson—ReutersWith the country's most populous state entering the fourth year of a devastating drought, Governor Jerry Brown has ordered an overall 25 percent cut in urban water use though the first statewide mandatory reductions in California's history. The suppliers with the highest per capita water use would have to accept a 36 percent cut. Lucy Nicholson—ReutersA tractor ploughs a field next to a canal in Los Banos, Calif. on May 5, 2015. California water regulators on Tuesday adopted the state's first rules for mandatory cutbacks in urban water use as the region's catastrophic drought enters its fourth year. However, the state's massive agricultural sector, which the Public Policy Institute of California says uses 80 percent of human-related consumption, has been exempted from cutbacks.Lucy Nicholson—ReutersA worker walks through farm fields in Los Banos, Calif. on May 5, 2015. Urban users will be hardest hit, even though they account for only 20 percent of state water consumption.Lucy Nicholson—ReutersApproximately 9 million acres of farmland in California are irrigated, representing roughly 80% of all human water use. But, farm production and food processing only generate about 2% of California’s gross state product, down from about 5% in the early 1960s.Lucy Nicholson—Reuters"In the Central Valley, where most agricultural water use occurs, the failure to manage groundwater sustainably limits its availability as a drought reserve. The increase in perennial crops—which need to be watered every year—has made the region even more vulnerable," the Public Policy Institute of California states. Lucy Nicholson—ReutersCentral Valley farmers have witnessed land sinking by as much as 3 feet, San Francisco Gate reports, as water agencies tap underground reservoirs at unprecedented depths. Water pours into a canal in Los Banos, Calif., May 5, 2015. Lucy Nicholson—ReutersLivestock products, including meat, dairy and eggs, account for more than a quarter of California's agricultural sector, a $12.5 billion industry, according to the USDA. Cattle are among the most water-hungry livestock, consuming an average of106 gallons per pound of beef. Cattle are seen at Harris Ranch in Coalinga, Calif. on May 5, 2015. Lucy Nicholson—ReutersCalifornia's planting of staple crops such as cotton, corn, oats, barley, wheat, rice, and sunflowers will total 1.72 million acres in 2015, down from 1.90 million acres in 2014, according to data from the National Drought Mitigation Center. A wheat field is seen in Los Banos, Calif. May 5, 2015. Lucy Nicholson—ReutersA water protest sign is seen in Los Banos, California, United States May 5, 2015. Central Valley counties suffer some of the highest unemployment rates in the state, topping out at more than 20% in Colusa County, according to the state's Legislative Analyst's Office.Lucy Nicholson—Reuters
