Douglas: Can your aching knees really predict the weather?

Meteorologist Paul Douglas answers reader questions about the weather and other natural phenomena every couple of weeks. Submit your own questions below. Hi Paul. Happy fall from an overlook on the Pine River, in beautiful downtown Pine River! My photo begs the question as it pertains to the old salt’s adage “Red sky at night/Sailors delight; Red sky at morning, sailors take warning.” What is the meteorological logic behind this folk wisdom and where and when are its origins and implications? Thanks a bunch for your learned hunch! - Steven Gieneart Thanks for a great question, Steve. It got me thinking about the weather proverbs we’ve grown up with. Long before Doppler radar, people studied the sky and behavior of animals to get a read on what the weather might do in the near future. Turns out those old adages that grandma liked to share (incessantly) have some scientific validity, after all. The one you’re referencing also comes up in the Bible. In the Gospel of Matthew, Jesus of Nazareth responds to religious leaders who ask him for a sign from heaven. He replies: “ In the evening you say, ‘Tomorrow will be fair, for the sky is red;’ and, in the morning, ‘Today will be stormy, for the sky is red and threatening .’” Advertisement We’ve all seen cherry-red sunrises and there’s a scientific reason for that. At sunrise and sunset, sunlight travels a much longer path through the atmosphere. Much of the shorter-wavelength blue light gets scattered out of the direct beam, allowing longer-wavelength reds and oranges to dominate. A red sunrise can illuminate clouds advancing from the west, while relatively clear conditions to the east allow sunlight through. One translation: Nice weather may be departing, with clouds and storms approaching from the west, since weather systems generally track from west to east. The converse: You’re looking to the west, where “new weather” usually approaches from. A brilliant red sunset may indicate that western skies are clearing. Translation: Bad weather may be moving away, with improving conditions heading your way. It doesn’t always hold up — there are exceptions to every rule — but it’s often an effective predictor of a short-fuse “Nowcast” (next few hours). Now, what about those other weather proverbs? Do they stand the test of time, and science? Let’s see: Expanded image view A halo surrounds the sun over the Gulf of Alaska during a NOAA ocean-mapping expedition. ( NOAA Ocean Exploration, Seascape Alaska/Provided by NOAA ) “ A ring around the sun or moon means rain soon .” A luminous halo is caused by ice crystals suspended in a high-altitude film of cirrostratus clouds (usually 25,000 feet high) refracting the light. These wispy clouds are often the leading edge of an approaching warm front. As the warm front arrives over 12 to 24 hours, clouds thicken, pressure drops, and precipitation follows. Scientific validity: high. Advertisement Advertisement “ Birds fly low before a storm .” Ornithology, the study of bird behavior, is driven by availability of food and subtle changes in atmospheric pressure. When a storm system moves in, a sudden drop in air pressure can cause discomfort or pain in a bird’s sensitive inner ears, prompting them to fly at lower altitudes where air pressure is slightly higher. A drop in air pressure also thins the air, making it harder for insects (a bird’s primary food source) to fly at high altitudes. The birds simply follow their next meal. Scientific validity: moderate to high . Advertisement “ If the wind’s in the east, ‘tis neither good for man nor beast.” In the Northern Hemisphere, surface winds blowing from the east or northeast often signal that a low-pressure system is passing to our south. Most (but not all) storms are preceded by winds blowing from the southeast, east or northeast, shifting to northwest behind the storm, as precipitation tapers. This proverb holds up, most of the time. Scientific validity: moderate. Expanded image view Towering thunderstorm clouds rise above the landscape. ( Paul Douglas/Provided by Paul Douglas ) “ When clouds appear like rocks and towers, the earth’s refreshed by frequent showers. ” Ask a farmer, gardener or fisherman. The “rocks” describe billowing, cauliflower-like lumps of cloud associated with rapidly-rising air. “Towers” describe their dramatic vertical growth — sometimes 10 miles into the atmosphere, like a full-blown cumulonimbus cloud or thunderstorm. NOAA identifies towering cumulus clouds as evidence of a relatively deep layer of unstable air, with strong potential for showers and T-storms. It’s not a guarantee of rain at your exact location, but a strong indicator that the atmosphere overhead is ripe for showery rain nearby. Scientific validity: high . Related Coverage Weather Douglas: Where should I retire in a warming world? Weather Douglas: Why road noise is louder on some mornings than others Weather Douglas: Could El Niño deliver a super-sized autumn and mild winter? “ Aches and pain, coming rains .” When air pressure drops, there is less physical resistance pressing against the human body. In joints affected by arthritis, inflammation, or old injuries (like a broken bone), the surrounding tissues can expand slightly in response to the lower pressure, causing more nerve irritation. An aching knee or sore shoulder can signal a storm hours — sometimes a full day — before precipitation arrives. Next time Aunt Gertrude complains about her arthritis, you might just want to pay attention. Scientific validity: moderate to high. Most Read ELECTIONS Make sense of Minnesota’s midterm election with these six charts Politics What Stephen Miller’s rise in the White House means for Minnesota Sports Scoggins: This baffling decision by P.J. 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