Alan Sealls photo
What causes the bizarre "hole-punch" clouds like the one seen above? The National Center for Atmospheric Research (NCAR) has just published a scientific paper addressing this wonder of nature. During certain conditions, flying airplanes can sometimes "seed" clouds, resulting in brief and highly-localized snow or rain falls. According to the NCAR, air is rapidly cooled behind the propellers of prop planes or as the wings of jets cut through the clouds. Water droplets in the cloud freeze and then fall to Earth, leaving the telltale hole in the cloud. From the National Science Foundation:
Precipitation from planes may be particularly common in regions such as the Pacific Northwest and western Europe because of the frequent occurrence of cloud layers with supercooled droplets, Heymsfield says...
Researchers have proposed a number of possible aviation-related causes, from acoustic shock waves produced by jets, to local warming of the air along a jet's path, to the formation of ice along jet contrails. Indeed, the earliest observations implicated jet aircraft, but not propeller aircraft, as producing the holes.
Researchers in the 1980s observed that propeller aircraft could transform supercooled droplets into ice crystals, and experiments were launched in the 1990s to characterize the phenomenon.
But scientists had not previously observed snow as it fell to the ground as a result of aircraft until Heymsfield and his colleagues happened to fly through some falling snow west of Denver International Airport with an array of instruments.
"Mysterious Clouds Produced When Aircraft Inadvertently Cause Rain or Snow"
Thirty years ago today, the Voyager 1 spaceprobe had completed its ncounters with the outer planets and was careening out of our solar system. The time came to shut off the probes’ cameras to preserve power and memory for the other onboard scientific instruments. But before engineers flipped the switch, one last photo opportunity was […]
While scientists have studied Moon rocks for 50 years, researchers have for the first time conducted deep analysis on a single grain of lunar dust, atom by atom. Using a common materials science technique called atom probe tomography that’s not widely used by geologists, the Chicago Field Museum’s Jennika Greer and colleagues probed the grain […]
This is so amazing. Watch what happens when a blacksmithing anvil is lowered into a large vat of pure liquid mercury. Update: One of our readers posted the link to the original video in the comments. I have replaced the animated GIF. Thanks, Crispy75. [H/t Alberto Gaitán via Bryce Lynch] Image: Screengrab from GIF
While we all love our iPhones and iPads, celebrating the releases of their latest and greatest versions, it’s amusing to consider how much we at the same time HATE the main item that keeps these little tech marvels powered up and working. No, Lightning cables don’t exactly inspire feelings of awe and wonder. It’s more […]
Every family is chock full of stories. Stories of history, stories of memory, stories of accomplishment and stories of love. From a grandparent’s tales of life decades ago to a couple’s first meeting to amazing life experiences and moments that you wish could be preserved for future generations. Unfortunately, we all don’t have the literary […]
Minimalism isn’t just trendy, it’s also wise. Clearing clutter and keeping things simple in your home is great for both your mind and for the earth. Bring that movement to your bedside when you replace just about everything on and around your nightstand with the Tree of Light: Wireless Charger + Bluetooth Speaker + LED […]