Posts Tagged ‘snow’

From an Atmospheric River to a River of a Sediment

February 21st, 2017 by Adam Voiland

Credit: NASA Earth Observatory/VIIRS/Jesse Allen. More details about the image here.

In the past two months, weather reports in California, Oregon, and Washington have been filled with news of “atmospheric rivers” bringing copious amounts of rain and snow to the western United States. Atmospheric rivers are long, thin fingers of moisture that develop in the tropics and flow into higher latitudes. If one of them makes landfall, huge of amounts of rain and snow can fall in a short period.

Much of this moisture, of course, eventually finds its way back to the sea through rivers. When waterways are swollen and flowing rapidly, they also become rivers of suspended sediment, full of clay, mud, sand, and other debris. Though the flooding from atmospheric river events can be devastating, the enormous amount of sediment they send rushing into the sea can also be surprisingly beautiful.

For instance, on February 11, 2017, the Visible Infrared Imaging Radiometer Suite (VIIRS) on Suomi NPP acquired this remarkable view of rivers and streams spewing sediment into the Pacific Ocean. Close to the outlets of streams and rivers, sediment-rich waters appear brown. As the sediment dissipates and mixes into the ocean, the water appears teal.

Duane Waliser, a scientist at NASA’s Jet Propulsion Laboratory, recently tallied just how damaging atmospheric rivers can be for coastal areas. In a study published in Nature Geoscience, Waliser and a colleague showed that atmospheric rivers are among the most damaging storm types in the middle latitudes. Of the very wettest and windiest storms (those ranked in the top 2 percent), atmospheric rivers were associated with nearly half of them. Waliser and colleagues also found that atmospheric rivers were associated with a doubling of the typical wind speed compared to all storm conditions.

Image originally published by NOAA.

Let It Snow: Winter 2016

December 23rd, 2016 by Pola Lem

Eighty five years ago today, Wilson Alwyn Bentley died of pneumonia. It was December 23, 1931, and outside his home in Jericho, Vermont, the sky was ripe for snow. His final diary entry read: “Cold north wind afternoon. Snow Flying.” It was the sort of weather he had lived for.

Bentley began to observe snow at 15 years old, when his mother bought him a microscope. It consumed his days, he later recalled:

When the other boys of my age were playing with popguns and sling-shots, I was absorbed in studying things under this microscope: drops of water, tiny fragments of stone, a feather dropped from a bird’s wing, a delicately veined petal from some flower. But always, from the very beginning, it was snowflakes that fascinated me most. The farm folks, up in this north country, dread the winter; but I was supremely happy.

Over the subsequent decades, Bentley photographed more than 5,000 snowflakes, and created the first photomicrograph of an ice crystal, combining a microscope and an accordion-shaped bellows camera. A professor of natural history who became known as “the snowflake man,” he demonstrated what is now a common adage: no two snowflakes are alike.

Snowflake photos by Wilson Bentley circa 1902. Courtesy of Wikimedia Commons.

Photos: Snowflakes circa 1902 by Wilson Bentley. Courtesy of Wikimedia Commons.

The snow Bentley observed at a microscopic scale, satellites now see at the size of whole continents. The subject matter that fascinated him still provides fodder for heaps of scientific papers today.

December 2016 has brought a flurry of Bentley-esuqe weather to the U.S. East Coast, including snow and biting winds. But long before winter kicked into full gear in cities like Washington and New York, it painted landscapes around the world white. From Japan to Kazakhstan, NASA satellites observed snow from space. So if you’re dreaming of a white Christmas or waiting for the gingerbread cookies to bake, here are several images—some we previously published, and others that are quite fresh.

Image: NASA Earth Observatory/Joshua Stevens, using Landsat data from the U.S. Geological Survey.

Image: NASA Earth Observatory/Joshua Stevens, using Landsat data from the U.S. Geological Survey.

December 19: ‘Gateway to the Desert’ Gets First Snow in 37 Years

Snow fell in the town of Ain Sefra for the first time in nearly four decades this December. Satellites show a thin, white veil covering the orange sand dunes of the northern Sahara. The Enhanced Thematic Mapper Plus (ETM+) on the Landsat 7 satellite captured this natural-color image of snow on December 19, 2016. On the ground, Photographer Karim Bouchetata captured the snow before it melted.

NASA Earth Observatory image by Joshua Stevens using VIIRS day-night band data from the Suomi National Polar-orbiting Partnership.

Image: NASA Earth Observatory/Joshua Stevens using VIIRS day-night band data from the Suomi National Polar-orbiting Partnership.

December 14: The Great Lakes Don a White Cloak

An Arctic air mass brought more snow to communities around the Great Lakes on December 14, 2016. The lake-effect snow comes on the heels of an earlier accumulation that piled up to several feet of snow in some areas, according to reports. Officials issued weather warnings and advisories from northeast Ohio to upstate New York.

Image: NASA Earth Observatory/Jeff Schmaltz, using MODIS data from LANCE/EOSDIS Rapid Response.

Image: NASA Earth Observatory/Jeff Schmaltz, using MODIS data from LANCE/EOSDIS Rapid Response.

December 2: Snow and ash above Katmai

A plume of volcanic ash hangs over the Gulf of Alaska in this natural-color image. The plume is not the product of an active volcano; it contains re-suspended ash from the 1912 eruption of Novarupta, according to the Alaska Volcano Observatory.

Photographs: Astronaut photography from the Expedition 48 crew.

Photograph: Astronaut photography from the Expedition 48 crew.

November 27: Snow 2.0

The white hills sprawling in every direction look like mounds built by snow plows, or massive hills of sugar. In fact, they’re the world’s largest gypsum dune field: the White Sands National Monument, located in southern New Mexico.

During the last Ice Age, melting snow and ice from the San Andres Mountains (west of the dunes) and the Sacramento Mountains (to the east) eroded minerals from the hillsides and carried them downhill to the basin below. As the climate warmed and the water evaporated, the basin remained full of selenite (the crystalline form of gypsum) and created the Alkali Flats. Over time, winds broke the crystals into sand grains, which built up into the dunes.

Image: NASA Earth Observatory/Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response.

Image: NASA Earth Observatory/Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response.

November 25: Rare November snow in Tokyo

On November 24, 2016, Tokyo received its first November snowfall in more than half a century. The snow fell in and around the Japanese capital, coating the metropolitan area.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image the same day. Central Tokyo is gray-brown in color, suggesting less accumulation or faster melting. Urban centers tend to shed snow faster than surrounding countryside because they are often hotter, a result of the urban heat island effect.

Image: NASA Earth Observatory/Pola Lem, using MODIS data from LANCE/EOSDIS Rapid Response.

Image: NASA Earth Observatory/Pola Lem, using MODIS data from LANCE/EOSDIS Rapid Response.

November 20: White hills appear amid green in England

Snow arrived in parts of northern England before a satellite took this image on November 20. According to reports, the same storm brought high winds and lashing rain farther south, in Kent and Sussex.

Image: NASA Earth Observatory/Pola Lem, using MODIS data from LANCE/EOSDIS Rapid Response.

Image: NASA Earth Observatory/Pola Lem, using MODIS data from LANCE/EOSDIS Rapid Response.

November 17: White Kazakhstan

Broad swaths of Kazakhstan turned white before this Visible Infrared Imaging Radiometer Suite (VIIRS) image was taken on November 17, 2016. Parts of the country saw temperatures dipping well below freezing, with extreme wind chills. That’s not a surprise for locals; the country’s capital, Astana, often experiences frigid days in winter months.

Holuhraun’s 2015 flow appears dark against the Icelandic snowscape. Image: NASA Earth Observatory/Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 team.

Image: NASA Earth Observatory/Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 team.

November 5: Snow meets lava in Iceland

More than a year after the latest eruption at Iceland’s Holuhraun lava field, the newly-formed lava may still be toasty underneath. Although the basaltic rock formed a hard crust, according to volcanologists, the flow is probably still hot enough to prevent snow from building up atop it.

“You’re not going to freeze the lava flow,” said Erik Klemetti, a volcanologist at Denison University and author of the Eruptions blog at Wired magazine. “You need to wait for the soil to freeze to get snow to accumulate in temperate latitudes.”

Mullen, Nebraska, sees an average of 1 inch (2.5 centimeters) of snow each October, according to U.S. climate data. On October 6, the area received roughly 2 inches (5 centimeters) of snow, according to the National Weather Service. Image: NASA/Jeff Schmaltz.

Image: NASA/Jeff Schmaltz.

October 7: Early snow blankets Nebraska

Snow dusted parts of Nebraska on October 6, 2016. This natural-color image, acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, shows a white blanket covering about 40 square miles (more than 100 square kilometers). Photos taken by highway cameras showed snow falling along parts of U.S. Route 83 on the afternoon of October 6.

 

Parade of Volcanoes

January 17th, 2012 by Jesse Allen

It’s been a really active time for the Earth Observatory and volcanoes. In the past three weeks, we’ve posted images of a night-time eruption of Shiveluch, ongoing activity at Puyehue–Cordón Caulle, daytime activity at the Kizimen Volcano, and my own favorite, a brand new island in the Red Sea. And those are just the images we published!

In recent weeks, we had a good shot of activity at Kilauea, but we skipped it since it only had Halema’uma’u activity — which is much like previous images and not the new ocean entry point, which we’ve yet to glimpse in cloud-free satellite imagery. We received an excellent ALI scene of the submarine El Hierro volcano (which we published) and then the next day we received an image of the same volcano from Landsat 7  (which effectively got scooped by ALI).

Another of the moderately recent and interesting images of volcanoes we didn’t use is a very nice ALI shot of the Cerro Hudson volcano in Chile.

We do have a good reason for not using the image. Notice the volcanic activity? Yeah, we didn’t see anything either. What makes this image interesting (to me anyway) is that just two weeks earlier, it looked like this:

We did publish that one. There’s actually not much in the way of activity in that one either, but in the published image, you can see a lot of ash that’s fallen on the ground from activity in October at the volcano.

Just two weeks later, with no new activity, almost all the ashfall seems to have “disappeared.” Fresh snow fell and covered much of it. Also, we got a much better shot with ALI of the volcano, getting a very nice view of the entire caldera, the glacier draining it out of the northeast, and forests in the alpine valleys. The ashfall was nowhere near as extensive and damaging as the Puyehue eruption, which at one point spewed out ash that circled the globe.