A Massive Dust Cloud Is Moving From the Sahara to the U.S. This Week
A massive cloud of dust from the Sahara Desert is expected to reach the Southeastern U.S. by Wednesday.
While the weather pattern driving the cloud is not unusual, the amount of dust is, according to KSLNewsRadio. National Aeronautics and Space Administration (NASA) Colonel Doug Hurley snapped a photo from on board the International Space Station, as NDTV reported.
"We flew over this Saharan dust plume today in the west central Atlantic," he tweeted Sunday. "Amazing how large an area it covers!"
We flew over this Saharan dust plume today in the west central Atlantic. Amazing how large an area it covers! https://t.co/JVGyo8LAXI— Col. Doug Hurley (@Col. Doug Hurley)1592768779.0
The dust is part of something called the Saharan Air Layer (SAL), a mass of dry, dusty air that travels over the North Atlantic every three to five days between mid June and mid August, according to National Oceanic and Atmospheric Administration (NOAA) information reported by KSL.
"Every so often, when the dust plume is large enough and trade winds set up just right, the dust can travel thousands of miles across the Atlantic and into the US." CNN Meteorologist Haley Brink said.
The current plume emerged off of North Africa last weekend and has already traveled more than 3,000 miles to reach the eastern Caribbean Sea, The Weather Channel reported.
Ok, last dust pic for today and this one is perhaps the most incredible yet. The comparison photos were sent to me… https://t.co/ZGUEu33e2p— Mark Sudduth (@Mark Sudduth)1592780353.0
It covers an area larger than the lower 48 states and Western Europe.
The dust is expected to travel more than 5,000 miles to reach the U.S., according to CNN. But its effects for the country will mostly be positive: brilliant sunsets and suppressed hurricane activity.
A computer model forecast of atmospheric dust for the next 10 days. The plume of Saharan dust is expected to move o… https://t.co/RY57M1ODJg— NWS Eastern Region (@NWS Eastern Region)1592597655.0
The sunsets are because the tiny dust particles tens of thousands of feet in the air filter the sun's rays at the beginning and end of the day. They also cause a blue sky at midday to have a milky sheen.
The hurricane suppression is because tropical storms don't do well with dry air.
"The SAL can have a significant negative impact on tropical cyclone intensity and formation," Jason Dunion explained for NOAA. "Its dry air can act to weaken a tropical cyclone by promoting downdrafts around the storm, while its strong winds can substantially increase the vertical wind shear in and around the storm environment. It is not yet clear what effect the SAL's dust has on tropical cyclone intensity, though some recent studies have suggested that it can actually impact the formation of clouds."
However, the cloud could worsen air quality in some places, which could make symptoms worse for people suffering from respiratory conditions like asthma, The Weather Channel pointed out.
The ghoulishly named ogre-faced spider can "hear" with its legs and use that ability to catch insects flying behind it, the study published in Current Biology Thursday concluded.
"Spiders are sensitive to airborne sound," Cornell professor emeritus Dr. Charles Walcott, who was not involved with the study, told the Cornell Chronicle. "That's the big message really."
The net-casting, ogre-faced spider (Deinopis spinosa) has a unique hunting strategy, as study coauthor Cornell University postdoctoral researcher Jay Stafstrom explained in a video.
They hunt only at night using a special kind of web: an A-shaped frame made from non-sticky silk that supports a fuzzy rectangle that they hold with their front forelegs and use to trap prey.
They do this in two ways. In a maneuver called a "forward strike," they pounce down on prey moving beneath them on the ground. This is enabled by their large eyes — the biggest of any spider. These eyes give them 2,000 times the night vision that we have, Science explained.
But the spiders can also perform a move called the "backward strike," Stafstrom explained, in which they reach their legs behind them and catch insects flying through the air.
"So here comes a flying bug and somehow the spider gets information on the sound direction and its distance. The spiders time the 200-millisecond leap if the fly is within its capture zone – much like an over-the-shoulder catch. The spider gets its prey. They're accurate," coauthor Ronald Hoy, the D & D Joslovitz Merksamer Professor in the Department of Neurobiology and Behavior in the College of Arts and Sciences, told the Cornell Chronicle.
What the researchers wanted to understand was how the spiders could tell what was moving behind them when they have no ears.
It isn't a question of peripheral vision. In a 2016 study, the same team blindfolded the spiders and sent them out to hunt, Science explained. This prevented the spiders from making their forward strikes, but they were still able to catch prey using the backwards strike. The researchers thought the spiders were "hearing" their prey with the sensors on the tips of their legs. All spiders have these sensors, but scientists had previously thought they were only able to detect vibrations through surfaces, not sounds in the air.
To test how well the ogre-faced spiders could actually hear, the researchers conducted a two-part experiment.
First, they inserted electrodes into removed spider legs and into the brains of intact spiders. They put the spiders and the legs into a vibration-proof booth and played sounds from two meters (approximately 6.5 feet) away. The spiders and the legs responded to sounds from 100 hertz to 10,000 hertz.
Next, they played the five sounds that had triggered the biggest response to 25 spiders in the wild and 51 spiders in the lab. More than half the spiders did the "backward strike" move when they heard sounds that have a lower frequency similar to insect wing beats. When the higher frequency sounds were played, the spiders did not move. This suggests the higher frequencies may mimic the sounds of predators like birds.
University of Cincinnati spider behavioral ecologist George Uetz told Science that the results were a "surprise" that indicated science has much to learn about spiders as a whole. Because all spiders have these receptors on their legs, it is possible that all spiders can hear. This theory was first put forward by Walcott 60 years ago, but was dismissed at the time, according to the Cornell Chronicle. But studies of other spiders have turned up further evidence since. A 2016 study found that a kind of jumping spider can pick up sonic vibrations in the air.
"We don't know diddly about spiders," Uetz told Science. "They are much more complex than people ever thought they were."
Learning more provides scientists with an opportunity to study their sensory abilities in order to improve technology like bio-sensors, directional microphones and visual processing algorithms, Stafstrom told CNN.
"The point is any understudied, underappreciated group has fascinating lives, even a yucky spider, and we can learn something from it," he told CNN.
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