The snowest countries

 

Tsunami

 

Cross section of a tsunami as its long waves move through the ocean and compress as they approach the coast.

Tsunami Propagation

Once generated, tsunamis radiate outward in all directions from their source. Unlike wind waves that affect just the surface of the ocean, tsunamis propagate (move) through the entire depth of the ocean, from the surface to the floor. They move at great speeds and have tremendous energy. Large tsunamis can move across entire oceans.

The speed of a tsunami depends on the depth of the water it is traveling through. The deeper the water, the faster the tsunami.

In the deep ocean, tsunamis can move as fast as a jet plane, over 500 mph (800 km/h), and can cross entire oceans in less than a day.

Enlarge tsunami energy/propagation map from the February 27, 2010, Pacific-wide tsunami.

The distance between waves is the wavelength. Because of a tsunami's long wavelengths, which can be hundreds of miles, a tsunami is barely noticeable in the deep ocean and rarely more than three feet (one meter) high.

Mariners at sea will not normally notice a tsunami as it passes beneath their hulls.

As a tsunami enters shallow water near land, it slows down, wavelengths decrease, waves grow in height, and currents intensify. At the shore, most tsunamis slow to the speed of a car, approximately 20 to 30 mph (30 to 50 km/h).

Enlarge tsunami energy/propagation map from the May 22, 1960, Pacific-wide tsunami.

Fast Facts

Tsunami speed can be computed by taking the square root of the product of the acceleration of gravity, which is 32.2 feet (9.8 meters) per second squared, and water depth. In 15,000 feet (4,600 meters) of water, this works out to almost 475 mph (765 km/h).

At rates like this, a tsunami will travel from Alaska's Aleutian Islands to Hawaii in about five hours; or from the Portugal coast to North Carolina in eight and a half hours.

https://cutt.ly/NwqCDUrB

Bacteria in the sky may help to make it rain

Here's how they do it.

By Veronique Greenwood

PSEUDOMONAS SYRINGAE

This species of bacteria can cause ice to form, even at temperatures that are warmer than freezing.

James Kremer and Sheng Yang He via Howard Hughes Medical Institute

Microbes are everywhere—in your gut, on your skin, even in the sky. Along with water vapor and particles, clouds also contain living bacteria. And certain airborne species have a superpower: They can cause water to freeze into ice, which in turn prompts the heavens to open. Once frozen granules form around bits of dust, minerals, or tiny organisms, they fall, melting on the way down to become raindrops or forming flakes to make snow. This means the little life-forms might contribute to rainfall—but how much?

“If you loaded up a cloud with these microbes, it would create freezing and the processes that lead to precipitation,” confirms University of Florida’s Brent Christner, who studies atmospheric bacteria. “The unknown factor is, are there enough of them up there to matter?” Christner and other researchers are sending weather balloons and planes on sampling missions to try to answer the question—and shed light on what these citizens of the sky get out of the deal. They might use clouds to travel long distances before raining down on fresh new habitats.

In the image below, scroll over each red dot to learn more about the mechanisms behind this stormy process.

Illustration by Valerio Pellegrini

This article originally appeared in the Extreme Weather issue of Popular Science.

FAVORITE IMAGES OF THE WEEK - 8

NASA/CampoAlto/V. Robles

Mars On Earth

Chile's Atacama Desert contains Earth's closest Mars-like conditions: It's extremely dry with high UV radiation from the sun. So naturally, NASA has made the area it's go-to practice facility for tests and experiments that they may one day perform on the red planet. Recently, scientists from NASA’s Atacama Rover Astrobiology Drilling Studies completed their second season of tests. The tested KREX-2 rover was able to rove, drill, and detect life signs all at the same time. Such multi-tasking robotic rovers could ultimately help scientists to figure out if there was (or still is) microbial life forms under Mars' surface.

Image courtesy of UW–Madison

A Simulated Tornado

Believe it or not, it’s springtime. And with it comes Tornado season—and tornado simulations. By modeling real data with a supercomputer, a team led by Leigh Orf at the University of Wisconsin–Madison has re-created this tornado-producing supercell that spawned several strong tornadoes in May 2011, including the EF-5 that touched down near El Reno, Oklahoma and caused a 63-mile path of destruction. These simulators can help us better understand the formation and structure of this extreme weather form.

NASA/Chris Gunn

NASA's Ghosts

It takes some artistic tricks to see ghosts around a space telescope. A NASA photographer recently captured this amazing and freaky picture during a lights-out inspection on the James Webb Space Telescope at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Because the special flashlights used for testing worked better in the dark, the engineers kept the lights off. To combat the dim (or nonexistent) light, the photographer used a longer than normal exposure, making the moving technicians look like blurred ghosts.

X-ray: NASA/CXC/University of Alberta/A.Bahramian et al.; Illustration: NASA/CXC/M.Weiss

A Black Hole Meets A White Dwarf Star

In a new study out this week in the journal, Monthly Notices of the Royal Astronomical Society, researchers found a white dwarf star orbiting around a black hole. It's a pretty rare find. Only a handful of binary systems like this one have been found in such dense globular star clusters. The researchers hope to learn more about this star-and-black-hole pair in future, and space-based gravitational wave observatories could be the key to its secrets.

FAVORITE IMAGES OF THE WEEK - 5

NASA/Joshua Stevens

The West Coast has been hit bad this week with torrential rain and snowfall. This .gif shows the precipitation, which is measured every 30 minutes, from Jan. 7 through Jan. 10. It's intense; California’s Mammoth Mountain received some 133 inches.

Rebecca Saxe, Atsushi Takahashi and Ben Deen / Department of Brain and Cognitive Sciences, MIT / Athinoula A. Martinos Imaging Center at the McGovern Institute for Brain Research, MIT

A new study out this week found that infants as young as four months old understand and process faces like adults do. The authors say that this suggests that the visual cortex in our brain is already highly structured and formed by the time we are born.

Apple

This week 10 years ago, Steve Jobs introduced the very first iPhone—a device that forever changed how we use and design mobile phones. Here’s what Twitter users thought about the device when the concept was brand new.

NASA

Obama On Mars

Though President Obama’s time as leader of the U.S. is coming to an end, his efforts can still be recognized in places as distant as Mars. This image, of the Curiosity rover’s deck (taken by one of its own cameras on its 44th Martian day on the red planet) contains the signatures of the outgoing president and his VP, Joe Biden.

USGS

Red Listed

The rusty-patched bumblebee just became the first bee species in the continental United States to join the endangered species list. According to the Fish and Wildlife service, the population has decreased by 87 percent since the 1990s. This decline is likely due to a combination of factors, including habitat loss, climate change, and pesticide use.

FAVORITE IMAGES OF THE WEEK - 3

Western Nanofabrication Facility

The World's Smallest Snowman

This snowman, which was promoted on Tumblr this Wednesday in honor of the winter solstice, is only 3 microns tall, making it the world's smallest. The snowman's body is made of 3 precisely cut 0.9 micron silica spheres that were pieced together by scanning a beam of electrons, a method often used to create teeny tiny unique shapes. The nose is made of platinum.

H/T Corey S. Powell via Twitter

WWF

Biodiversity Can Be Really Cute

This newt here, called Tylototriton anguliceps, is one of 163 animals found along the Mekong River in Southeast Asia that entered the new species class of 2015. It's nicknamed the Klingon newt, after the extraterrestrial humanoid species in Star Trek. Also listed is a David Bowie-esque snake that boasts quite glamorous scales.

Courtesy of NOAA Office of Ocean Exploration and Research, Hohonu Moana 2016

Casper The Octopus Is In Danger

This ghost-like octopus was just discovered last year off the coast of Hawaii, but already scientists think it might be in danger. These octopods lay their eggs on one particular type of sponge that grows on top of manganese deposits. Manganese is currently a heavily-mined mineral because of its usefulness in producing mobile phones and other tech gadgets. For now, because of a sufficient amount of manganese on Earth's surface, these animals are safe. But scientists don't know for how long.

Frederic Osada and Teddy Seguin/DRASSM/Stanford

Humanoid Diver

Who better to explore a dangerous underwater archaeological site than a human that's not actually a human? Stanford researchers built this hybrid humanoid/ROV robot that can reach dangerous depths of the ocean so humans don't have to. Unlike other ROVs, which are incredibly boxy and lack dexterity, this humanoid has two hands that real humans can manipulate to make the robot perform delicate tasks undersea.

H/T: IEEE Spectrum

NASA Earth Observatory image by Joshua Stevens

Desert Snow

Some deserts—ones that are very high up in altitude—get snow all the time. But the African Sahara rarely gets the pleasure of a white Christmas. This week though, snow blanketed the area, as seen in the satellite image above. The last time scientists recorded snow falling in this area was in February 1979. Read about this strange weather event—and other surprising snow days—here.

FAVORITE IMAGES OF THE WEEK - 2

NASA

Hurricane Tracker

A NASA mission called the Cyclone Global Navigation Satellite System (CYGNSS), which includes eight small satellites, launched this week. Its goal is to better understand how hurricanes form in order to more accurately predict how and when they will occur. One advantage of this system is that it will focus only on areas around the tropics, where most hurricanes form.

XPRIZE

Patient, Diagnose Thyself

In many ways, the tricorder in Star Trek is the ultimate piece of medical technology: A handheld device that can diagnose any disease in the body. In 2012, tech company Qualcomm created an XPRIZE competition to challenge engineers and doctors to create a device similar to the fictional tool. We took a first look at the two finalists' prototypes, which show us that our future doctor might simply be a tiny, high-tech medical box.

Joshua Stevens/NASA Earth Observatory

Snow Light

The weather these past two weeks has been rough for communities around the Great Lakes. Last week, the region was smothered with several feet of snow, and this week, an arctic air mass piled a few more feet on top. The Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite, which can detect even extremely dim light sources, took this image above. The white areas show where the full moon is reflecting off of large piles of snow.

Department of Transportation

Talking Cars

Behind the wheel, humans make mistakes and cause accidents. That's mostly because we have bad communication skills (among other reasons). To make roads safer, the U.S. Department of Transportation wants cars to "talk" to each other. New technology that forces cars to broadcast their surroundings to other vehicles might prevent many accidents in the future.

NASA/JPL-Caltech/Univ. of Arizona

Dry Ice Bubbles

These crazy land formations, which look more like human intestines, can only be found on the south pole of Mars. They form when dry ice (carbon dioxide), which makes up the pole, is punctuated with holes. Over time, air slowly leaks in and puffs up the surface.

T.H. Prettyman and N. Yamashita, Planetary Science Institute

Ceres On Ice

Scientists are pretty sure that Ceres, the dwarf planet between Mars and Jupiter, holds water. But a new paper out this week suggests that it might contain more than liquid H2O: A portion of its surface, particularly near the poles, could be coated in a thin layer of ice. Studying how it built up there will help researchers understand how ice forms all over our solar system.

FAVORITE SCIENCE PICS - 2

NOAA/NASA

A Puzzling Mega-Storm

Here's what Invest 99L looked over the Leeward Islands on the afternoon of August 24, 2016, from the point-of-view of a weather satellite. Some weather models initially showed the disturbance developing into a major hurricane or tropical storm. And while the latest forecasts are tamer, it could still causing major flooding in South Florida and the Bahamas

Nature Conservancy

Migration in Motion

As climate change warps the preferred habitats of mammals, birds and amphibians, these animals will be forced to flee. A beautiful but troubling new map predicts what this massive migration might look like for North and South America. Ecologist Dan Majka and other researchers from the Nature Conservancy and the University of Washington plotted the likely routes of 2,954 species as they travel from their current habitats to areas that will better suit their needs.

Kevin Gill via Flickr

Saturn's Trippy Rings

Saturn’s moon Daphnis is only five miles in diameter, but its orbit can still make some waves. The tiny moon travels within the Keeler Gap, a space about 26 miles wide in Saturn’s A ring, keeping it clear. It also causes the edges of the gap to ripple as it swings past. Two new visualizations by NASA software engineer Kevin Gill illustrate how this interaction might look

Dave DeMar/Burke Museum

Tyrannosaurus rex Skull

Paleontologists work to remove the massive skull of a T. rex from a fossil site in Montana. The skull is encased in plaster to ensure its safety. The recently-discovered skull of the teenage Tyrannosaurus rex was 4 feet long when it died, around 66 million years ago.

Nick Hobgood (Nhobgood on Wikimedia Commons)

Really Big Nest Egg

A fisherman from the Philippines discovered a giant pearl a decade ago, and kept it under his bed as a good luck charm until this year. Now some estimates put its value at as much as $100 million. The giant pearl supposedly formed inside a giant clam — like this Tridacna giant clam in Komodo National Park, Indonesia — which in and of itself is unusual, as clams rarely make pearls.

SASTIND/Xinhua

China's Mars Rover

This week, China unveiled illustrations of its Mars probe and rover, following earlier announcements of its plan to land on the trendiest planet for bots. The craft will include an orbiter, a landing capsule, and a rover. China is aiming for a summer of 2020 launch on a Long March 5 carrier rocket from the Wenchang space launch center in south China’s Hainan province, according to state media.